論文 - 寺川　光洋

Laser direct writing of graphene quantum dots encircling conductive structures for stimuli-responsive anti-counterfeiting label

Kosuke Tsukada, Mitsuhiro Terakawa

Optics Express （Optica）  33   19479 2025年04月

共著, 最終著者, 責任著者, 査読有り

Direct Writing of Conductive Microstructures inside a Thermoresponsive Hydrogel

Kashikawa K., Onoe H., Terakawa M.

ACS Applied Polymer Materials 7   4771 2025年

　概要を見る

The integration of soft electronic devices with biological systems has garnered increasing attention for applications such as bioinspired soft robotics and wearable health monitors. These devices are designed to interface with biological surfaces or tissues, mimicking the transmission of electrical signals through neural tissues while ensuring high biocompatibility and flexibility. Conductive polymer hydrogels, combining conductive polymers and hydrogels, have emerged as promising materials owing to their flexibility, stretchability, and biocompatibility. In the realization of advanced soft electronic devices, it is key to employ materials with high flexibility and biocompatibility and, moreover, develop techniques for the fabrication of precise and localized conductive structures inside hydrogels. In this study, we demonstrated the spatially selective polymerization of conductive polymers inside a thermoresponsive hydrogel. A poly(N-isopropylacrylamide) (PNIPAM) hydrogel was immersed in a precursor solution of polyaniline (PANI), and polymerization was induced by femtosecond laser pulse irradiation. Conductive polymer microstructures were successfully fabricated inside the hydrogel. Furthermore, using the thermal responsiveness of the PNIPAM hydrogel, we demonstrated that the electrical resistance of the PANI structures changed in response to temperature. The present method provides a strategy for the precise and localized fabrication of conductive structures inside hydrogels, offering an approach to the fabrication of soft electronic devices.

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High-resolution patterning of graphitic carbon structures in laser-induced graphitization of cellulose nanofiber film

Yosuke Kondo, Ken Kashikawa, Mari Kato, Mitsuhiro Terakawa

Optical Materials Express （Optica）  15 （ 1 ） 95 - 103 2024年12月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り

　概要を見る

In laser-induced graphitization, decreasing the linewidth of patterned structures is key to enhancing the potential in microdevice fabrication. In this study, we demonstrated that graphitic carbon structures with narrow linewidth can be directly patterned in laser-induced graphitization of cellulose nanofiber (CNF) film by immersing the film in CaI2 solution. The linewidth of the structures increased with increasing laser power, indicating that the linewidth can be readily controlled. Based on the above findings, we patterned multiple concentric structures with precisely controlled linewidth to fabricate a Fresnel zone plate, which can focus laser light in the visible wavelength range.

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Laser-induced formation of fine porous graphitic carbon for eco-friendly supercapacitors

M. Kato, S. Hayashi, R. Funayama, Y. Kondo, Y. Hattori, M. Terakawa

Advanced Engineering Materials （Wiley）  26 （ 23 ） 2401301 2024年09月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り,  ISSN  14381656

　概要を見る

An electric double-layer capacitor (EDLC), which is one of the pivotal energy storage devices, provides rapid charge–discharge capabilities and an extended cycle life. Areal capacitance, a key indicator of EDLC performance, increases with the specific surface area of its electrodes. This study demonstrates a method for significantly increasing the specific surface area in the laser-induced graphitization of biodegradable polymers by incorporating NaHCO3 into the composite sheet, generating not only microscale pores but also a large number of nanoscale fine pores. Furthermore, it shows that using these structures as EDLC electrodes leads to a substantial increase in areal capacitance. An increase in the number of fine pores formed in the structure and a corresponding rise in the areal capacitance of the fabricated EDLC are observed with the increase in the NaHCO3 weight ratio. Notably, the composite sheets are composed of natural-derived, biodegradable materials, while NaHCO3 is known for its low corrosivity and biotoxicity. The proposed method thus offers a pathway for fabricating energy storage devices with minimal environmental impact, ensuring their eco-friendly disposal post-use.

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Light-triggered transmittance control in thermoresponsive hydrogels by femtosecond laser direct writing

K. Kashikawa, H. Tomikawa, H. Onoe, M. Terakawa

ACS Applied Optical Materials （ACS）  2 （ 4 ） 565 - 573 2024年03月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り

　概要を見る

Thermoresponsive hydrogels, which exhibit changes in their optical properties and volume due to temperature variations, are promising candidates for applications in soft devices. In this study, we demonstrate the modulation of transmittance in a thermoresponsive hydrogel through light stimulation employing gold microstructures fabricated via multiphoton photoreduction. The spatial integration of photoresponsiveness, attributed to high-density gold nanoparticles within the thermoresponsive hydrogel, was accomplished through the high-speed laser scanning of femtosecond laser pulses. The temperature measurement during the fabrication of the gold microstructure revealed that the high-speed and multiple scanning over the same path effectively reduced the temperature in the irradiated area of femtosecond laser pulses. The present approach enabled the mitigation of thermal effects during the fabrication, resulting in minimizing distortion in the fine lines of the structures. Upon exposure to stimulus light, a rapid change in the transmittance of the region where the structures were fabricated was prominently observed. The present method unveils a promising avenue for the advancement of light-responsive soft devices.

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Temperature measurement and morphological/crystalline differences in the laser-induced carbonization of polydimethylsiloxane

M. Kai, S. Hayashi, K. Kashikawa, M. Terakawa

Optical Materials Express （OPTICA）  14 （ 4 ） 955 - 964 2024年03月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り,  ISSN  20102690

　概要を見る

Laser-induced carbonization, which allows for the facile generation of graphitic carbon, is considered a promising technique for fabricating arbitrary conductive microstructures. The morphology and crystallinity of the resulting product are acknowledged to be significantly influenced by laser irradiation conditions. However, unlike discussions pertaining to furnaces where detailed considerations of applied temperature and resulting products are common, discussions on the process of laser-induced carbonization are limited. In recent years, reports have shown that using polydimethylsiloxane (PDMS) as a precursor material not only produces graphitic carbon but also results in the formation of silicon carbide. In this study, we utilized a thermographic camera to measure temperature changes during laser-induced carbonization, aiming to elucidate the correlation between PDMS temperature fluctuations and the morphology and crystallinity of the resulting graphitic carbon. The results demonstrate that the morphology and crystallinity of the graphitic carbon formed through laser-induced carbonization are not solely determined by the maximum temperature in the laser-irradiated area. The temperature changes during laser irradiation play a crucial role in the selective generation of these materials.

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Defect-initiated formation mechanism of 3D carbon tracks on flexible transparent substrates by laser irradiation

S. Hayashi, X. Du, M. Rupp, K. A. Filsinger, M. Terakawa, C. B. Arnold

Optics and Laser Technology （ELSEVIER）  174   110686 2024年02月

共著, 査読有り,  ISSN  00303992

　概要を見る

Laser direct writing of 3D carbon structures onto flexible polymer substrates offers potential of rapid roll-to-roll manufacturing for a variety of key applications, including large area sensors, flexible electronics, robotics, energy storage/conversion, and other consumer applications. The specific formation mechanism of the carbon structures has been an issue of debate for many years with the prevailing notion of a simple photothermal conversion reaction that mainly depends on the total energy input. However, this view has been shown to be inconsistent with experimental observations of nonlinear changes in the resulting structures when multiple processing parameters are simultaneously changed. In this study, we propose a formation mechanism based on the nucleation and growth of laser-induced defects, which is experimentally validated by irradiating a continuous wave laser beam onto polydimethylsiloxane. The model is further validated by intentionally introducing controlled defects by femtosecond laser irradiation, and indicate the implications of a two-laser laser direct writing technique to go beyond the current processing limits. These results clarify the previously ambiguous mechanisms by which carbon structures form under laser irradiation and provide a deeper understanding of how to control photothermal processes for advanced material processing.

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Spatially-selective enhancement of mechanical strength through localized cross-linking of double network hydrogels

Kaneto Tsunemitsu, Akira Watanabe, Hiroaki Onoe, Mitsuhiro Terakawa

Optical Materials Express （OPTICA）  13 （ 10 ） 2914 - 2924 2023年09月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り

　概要を見る

To advance the development of flexible materials for soft robotics applications, it is crucial to enhance the elastic modulus and breaking the stress of soft materials, such as hydrogels. Double network hydrogels (DN gels) have displayed remarkable mechanical strength owing to their unique network structure composed of two types of polymer networks. However, current fabrication methods for DN gels entail cross-linking two distinct hydrogel polymers throughout the entire hydrogel matrix. In this study, we focused on employing multi-photon polymerization (MPP) with femtosecond laser pulses as a cross-linking method for hydrogels to achieve spatially selective formation of DN gel structures at the micrometer scale, along with the consequent improvement in local mechanical strength. We assessed the mechanical properties of the fabricated structures and confirmed that the mechanical strength varied within the regions where DN gel was locally formed.

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Laser-induced dielectric to conductor transformation on the surface of aluminium nitride ceramic

Nedyalkov N., Dikovska A., Nikov R., Koleva M., Grochowska K., Jendrzejewski R., Terakawa M.

Optics and Laser Technology （Optics and Laser Technology）  163 2023年08月

ISSN  00303992

　概要を見る

In this work formation of conductive lines on the surface of AlN ceramic induced by laser radiation is presented. The transformation to conductive state is done be ablation of the ceramic surface using nanosecond Nd:YAG laser. The dependences of the processing conditions as applied laser fluence and the pulse overlapping on the resistance value are obtained for different surface modifications including straight lines, ∟, and ┼ shapes. The formation of conductive structures is also studied for application of laser irradiation at the second (532 nm), third (355 nm) and fourth (266 nm) harmonics of the laser system. It is found that the resistance strongly depends on the processing conditions, as at appropriate choice it can be varied in a range of order of magnitude. Processing parameters windows are defined where the structure resistance has a minimal value. The performed analyses based on TEM, SEM, EDX, and Raman spectroscopy indicate that formation of aluminium layer, its oxidation and morphology define the processed areas conductivity. The role of oxidation is also confirmed by analyses of structures fabricated in vacuum, where significant reduction of the resistance is observed. It is found however, that a decrease of the ambient air pressure to 10 Torr is sufficient to obtain structures resistance of the same order as for processing in vacuum. Calculated data about the thickness of the conductive layer is also presented. The obtained results could be used in the design of microelectronic components, resistive elements, and novel optical materials.

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Cultivation and transplantation of three-dimensional skins with laser-processed biodegradable membranes

Yasuyuki Tsunoi, Izumi Takayama, Naonari Kondo, Yo Nagano, Hiromi Miyazaki, Satoko Kawauchi, Mitsuru Akashi, Daizoh Saitoh, Mitsuhiro Terakawa, and Shunichi Sato

Tissue Engineering Part A （Tissue Engineering - Part A）  29 （ 11-12 ） 344 - 353 2023年05月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  19373341

　概要を見る

For the treatment of irreversible, extensive skin damage, artificial skins or cultured skins are useful when allogeneic skins are unavailable. However, most of them lack vasculature, causing delayed perfusion and hence delay or failure in engraftment of the tissues. We previously developed a prevascularized three-dimensional (3D) cultured skin based on the layer-by-layer cell coating technique (LbL-3D skin), in which cells are seeded and laminated on a porous polymer membrane for medium supply to the thick cultured tissue. Recent animal studies have demonstrated that LbL-3D skin can achieve rapid perfusion and high graft survival after transplantation. However, there were practical issues with separating LbL-3D skins from the membranes before transplantation and the handling separated LbL-3D skins for transplantation. To address these problems, in this study, we examined the use of biodegradable porous polymer membranes that enabled the transplantation of LbL-3D skins together with the membranes, which could be decomposed after transplantation. Thin films made from poly (lactic-co-glycolic acid) (PLGA) were irradiated with femtosecond laser pulses to create micro through-holes, producing porous membranes. We designed and fabricated culture inserts with the PLGA membranes and cultivated LbL-3D skins with 2 × 106 neonatal normal human dermal fibroblasts and 1 × 104 human umbilical vein endothelial cells in the dermis of 20 cell layers and 1 × 105 neonatal human epidermal keratinocytes in the epidermis. Histological analyses revealed that the skins cultured on the PLGA membranes had thickness of about 400 μm and that there were no defects in the quality of the skins cultured on the PLGA membranes when compared with those cultured on the conventional (nonbiodegradable) commercial membranes. The cultured LbL-3D skins were then transplanted together with the PLGA membranes onto full-thickness excisional wounds in mice. At 7 days posttransplantation onto a mouse, the tissues above and below the membrane were connected through the holes with collagen-positive fibers that appeared to migrate from both the host and donor sides, and favorable reepithelization was observed throughout the transplanted skin region. However, insufficient engraftment was observed in some cases. Thus, further optimization of the membrane conditions would be needed to improve the transplantation outcome.

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Direct patterning of conductive structures on hydrogels by laser-based graphitization for supercapacitor fabrication

Rikuto Miyakoshi, Shuichiro Hayashi, Mitsuhiro Terakawa

Advanced Electronic Materials （Advanced Electronic Materials）  9 （ 5 ） 2201277 2023年03月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り

　概要を見る

Hydrogels have emerged as promising supporting materials for wearable or implantable electronic devices, owing to their high biocompatibility. Among the many techniques for patterning conductive structures on supporting materials, laser-based graphitization allows the simultaneous synthesis and patterning of conductive structures. Here, it has been demonstrated for the first time, the direct patterning of conductive structures on hydrogels by laser-based graphitization, and the application of this method to the fabrication of hydrogel-based supercapacitors. Conductive graphitic carbon is formed on the hydrogel along the trajectory of laser scanning. One-step fabrication of supercapacitors is achieved by laser irradiation of hydrogels containing both lignin and NaCl electrolyte. Notably, the areal capacitance of the fabricated supercapacitor is retained after drying and swelling, indicating its reusability. The method realizes rapid fabrication of hydrogel-based supercapacitors that can be stored in a dry state, providing a facile method for storing and delivering energy-storage devices.

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Formation of gold nanoparticles inside a hydrogel by multiphoton photoreduction for plasmonic sensing

Keiki Muranaka, Takuro Niidome, Maria Leilani Torres-Mapa, Alexander Heisterkamp, Mitsuhiro Terakawa

Plasmonics （Plasmonics）  18 （ 2 ） 751 - 760 2023年02月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り,  ISSN  15571955

　概要を見る

Plasmonic sensing using metal nanoparticles has received considerable attention because of its high sensitivity for detection. In this study, gold nanoparticles (AuNPs) were formed near the focal point of femtosecond laser pulses inside a hydrogel containing gold chloride and glutamine for plasmonic sensing. The presence of glutamine suppressed the formation of AuNPs in the region outside of the laser focal point. The proposed method for the formation of AuNPs enables spatially selective fabrication of structures with optical properties attributed to localized surface plasmon resonance. Typical biomolecules present in sweat were detected using hydrogels with the fabricated structures. Among the biomolecules, the peaks of the absorbance spectra of the AuNPs inside hydrogels exhibited a blue shift only for urea. This result indicates that urea can be detected using hydrogels with fabricated structures. The method presented in this study facilitates spatially selective fabrication of biosensing structures inside the bulk of hydrogels.

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Laser-induced graphitization of lignin/PLLA composite sheets for biodegradable triboelectric nanogenerators

R. Funayama, S. Hayashi, M. Terakawa

ACS Sustainable Chemistry & Engineering （ACS Sustainable Chemistry and Engineering）  11 （ 7 ） 3114 - 3122 2023年02月

共著, 最終著者, 責任著者, 査読有り

　概要を見る

With the rapid development of the Internet of Things (IoT), numerous electronic devices are expected to be installed in the natural environment. Triboelectric nanogenerators (TENGs) can be reliable devices providing on-site, clean, and sustainable power generation in nature. The fabrication of metal-free, biodegradable TENGs will reduce the environmental burden and disposal cost after usage. In this study, we demonstrate the direct fabrication of conductive graphitic carbon on a biodegradable polymer composite by laser-induced graphitization and apply the structures for metal-free biodegradable TENGs. Laser-induced graphitization of poly(lactic acid) (PLA) composite sheets was achieved for the first time by mixing alkaline lignin powder as a filler. The fabricated TENGs could generate electricity, and the power density reached ∼1.98 mW/m2 at a load resistance of 200 MΩ when the fabricated TENG was driven at a contact frequency of ∼1 Hz and a contact pressure of 1 N. Power generation by contact with water and plants was also demonstrated, showing its applicability for power generation in natural environments. The proposed method in this study offers the facile fabrication of biodegradable devices and the development of sustainable power generation devices.

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Direct writing of fluorescent semiconducting nanoparticles on polydimethylsiloxane by ultrashort-pulsed laser processing: Implications for electronic and photonic device fabrication

Shuichiro Hayashi, Mitsuhiro Terakawa

ACS Applied Nano Materials （ACS Applied Nano Materials）  6 （ 3 ） 2125 - 2132 2023年01月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り

　概要を見る

Laser direct-write (LDW) methods offer the rapid, on-demand, and high-resolution patterning of a variety of nanocrystals (NCs). Out of the many LDW methods, the laser-induced modification method is an attractive method as NCs can be directly patterned on polymers without supplementary preparation steps. Previously, it has been indicated that the laser irradiation of polydimethylsiloxane results in composite structures composed of graphitic carbon crystals (GCs) and silicon carbide NCs (SiC-NCs). However, material properties distinctive of SiC-NCs have not been reported for the resulting structures owing to the low formation content relative to those of GCs. In this study by utilizing a high-repetition femtosecond laser, we demonstrate the controlled formation of GCs and SiC-NCs to achieve a composite structure exhibiting a measurable semiconducting behavior for the first time. Moreover, photoluminescence emissions distinctive of fluorescent molecular-sized SiC-NCs were observed from the resulting structures. The presented results will trigger a wave of ideas utilizing ultrashort-pulsed lasers for the laser-induced modification of polymers toward the fabrication of a wide range of electronic and photonic devices, such as memory storage devices, photovoltaics, and optical sensors.

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Fabrication of biodegradable triboelectric nanogenerator by laser-induced graphitization of lignin/PLLA composite sheets

Funayama R., Hayashi S., Terakawa M.

Proceedings of SPIE - The International Society for Optical Engineering （Proceedings of SPIE - The International Society for Optical Engineering）  12408 2023年

ISSN  0277786X

　概要を見る

We demonstrate the direct fabrication of graphitic carbon on a biodegradable polymer composite by laser-induced graphitization and applied the structures for the electrode of metal-free biodegradable triboelectric nanogenerators (TENGs). The laser-induced graphitization of fully biodegradable composite sheets composed of alkaline lignin powder and poly(L-lactic acid) (PLLA) was realized. The fabricated TENGs generated electricity by contact with synthetic polymers and natural materials such as water and plant leaves, indicating their applicability for on-site power generation in the natural environment. The proposed method provides the facile fabrication of biodegradable devices and the development of sustainable power generation.

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Direct writing of conductive and semiconductive structures via the femtosecond laser-induced carbonization of a silicone elastomer

Hayashi S., Terakawa M.

Proceedings of SPIE - The International Society for Optical Engineering （Proceedings of SPIE - The International Society for Optical Engineering）  12411 2023年

ISSN  0277786X

　概要を見る

In this study, we patterned structures composed of graphitic and silicon carbide nanocrystals by the laser-induced carbonization of polydimethylsiloxane. The average size of the observed silicon carbide nanocrystals varied depending on the energy per laser pulse, or pulse energy, used for patterning, where larger crystals were observed for structures patterned with higher pulse energies. Moreover, the electrical property of the patterned structure shifted from conductive to semiconductive, as the pulse energy for patterning increased. To the best of our knowledge, this is the first demonstration of the patterning of structures exhibiting measurable semiconducting properties by the laser-induced carbonization of polymers.

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Simultaneous laser-based graphitization and microstructuring of bamboo for supercapacitors derived from renewable resources

Rikuto Miyakoshi, Shuichiro Hayashi, Mitsuhiro Terakawa

RSC Advances （Royal Society of Chemistry）  12 （ 46 ） 29647 - 29652 2022年10月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り

　概要を見る

Utilizing renewable resources for electrodes realizes the sustainable fabrication of a supercapacitor with high environmental friendliness. Laser-based graphitization of biomass has been emerging as a promising technique for patterning the electrodes of a supercapacitor with renewable resources. Herein, simultaneous patterning and microstructuring of laser-induced graphene (LIG) on a renewable biomass resource, bamboo, by a laser-based graphitization technique was demonstrated. By irradiating femtosecond laser pulses onto bamboo, graphitization and microstructuring were both induced simultaneously, forming conductive structures with high surface area. Furthermore, LIG patterned on bamboo by our method was used as the electrodes of supercapacitors. NaCl was selected as the electrolyte for the fabrication of supercapacitors. The proposed method realizes the fabrication of environmentally-friendly supercapacitors comprised of all renewable biomass resources.

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Light-driven flow control in the hydrogel microchannel by utilizing a metal microstructure fabricated by multiphoton photoreduction

Yo Nagano, Hiroaki Onoe, and Mitsuhiro Terakawa

Optical Materials Express 12 （ 8 ） 3303 - 3312 2022年08月

共著, 最終著者, 責任著者, 査読有り

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Laser-based molecular delivery and its applications in plant science

Heinemann D., Zabic M., Terakawa M., Boch J.

Plant Methods （Plant Methods）  18 （ 1 ）  2022年06月

　概要を見る

Lasers enable modification of living and non-living matter with submicron precision in a contact-free manner which has raised the interest of researchers for decades. Accordingly, laser technologies have drawn interest across disciplines. They have been established as a valuable tool to permeabilize cellular membranes for molecular delivery in a process termed photoinjection. Laser-based molecular delivery was first reported in 1984, when normal kidney cells were successfully transfected with a frequency-multiplied Nd:YAG laser. Due to the rapid development of optical technologies, far more sophisticated laser platforms have become available. In particular, near infrared femtosecond (NIR fs) laser sources enable an increasing progress of laser-based molecular delivery procedures and opened up multiple variations and applications of this technique. This review is intended to provide a plant science audience with the physical principles as well as the application potentials of laser-based molecular delivery. The historical origins and technical development of laser-based molecular delivery are summarized and the principle physical processes involved in these approaches and their implications for practical use are introduced. Successful cases of laser-based molecular delivery in plant science will be reviewed in detail, and the specific hurdles that plant materials pose will be discussed. Finally, we will give an outlook on current limitations and possible future applications of laser-based molecular delivery in the field of plant science.

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Nanosecond laser-induced oriented periodic structures on AlN ceramic

Nedyalkov N., Dikovska A., Nikov R., Nikov R., Dliova T., Atanasova G., Aleksandrov L., Karashanova D., Strijkova V., Terakawa M.

Applied Surface Science 585 （ 30 ） 152712 2022年05月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

This work presents results on nanosecond laser-induced surface structuring of AlN ceramic. The process under investigation is performed using the fundamental wavelength of Nd:YAG laser system. It is shown that the change of the ambient air pressure from atmospheric one to 10-4 Torr, leads to modification of the surface morphology – from ripples structure with a periodicity of about the incident irradiation wavelength, to an oriented periodic microstructure with a characteristic period in the range 10–15 µm. In all cases when the periodic structures are formed, a clear orientation perpendicular to the incident irradiation polarization is observed. The properties of the oriented periodic microstructures (OPMSs) formed at the lowest pressure condition are studied in more details, as the influence of the processing conditions on their characteristics is presented. It is found that the formation of OPMS requires a minimal laser pulse number and application of laser fluence above certain threshold. The surface of the fabricated structures is conductive, as the performed analyses indicate that the effect is related to presence aluminium in the processed areas. Possible mechanisms of formation of these structures are discussed. Ablation experiments using irradiation at 532 and 266 nm are also reported and discussed. The presented results may have significant impact when laser processing of AlN ceramics is considered, and for the design of structures with potential applications in microelectronics, tribology, and aluminium-based UV plasmonics.

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Tailored Structure and Antibacterial Properties of Silica-Coated Silver Nanoplates by Pulsed Laser Irradiation

E. Takeda, W. Xu, M. Terakawa, T. Niidome

ACS Omega （American Chemical Society）  7 （ 8 ） 7251 - 7256 2022年02月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

We coated triangular-shaped silver nanoparticles, a type of anisotropic nanoplate (NPL), with silica (i.e., prepared Ag@SiO2 NPLs). When we irradiated Ag@SiO2 NPLs with nanosecond-pulsed laser light for 10 s, the triangular shape changed to spherical because of the photothermal effect. A high laser power exposed the silver core, and the particles exhibited strong antimicrobial activity. In contrast, at a moderate laser power, the silica layer crystallized, and the particles’ antimicrobial activity decreased. Thus, a combination of Ag@SiO2 NPLs and an appropriately tuned power of pulsed laser irradiation facilitated a decreased or an increased antimicrobial activity.

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Multiphoton Photoreduction for Biomimetic Applications of Hydrogels

Nagano Y., Tsunemitsu K., Onoe H., Terakawa M.

Optics InfoBase Conference Papers （Optics InfoBase Conference Papers）  2022年

　概要を見る

Light-driven control of the flow velocity inside a hydrogel microchannel is demonstrated by fabricating metal microstructures by multiphoton photoreduction. A technique to evaluate the local strain and compression of the hydrogel will also be described.

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Laser Direct Writing of Graphene Quantum Dots inside a Transparent Polymer

Shuichiro Hayashi, Kaneto Tsunemitsu, Mitsuhiro Terakawa

Nano Letters （ACS Publications）  22 （ 2 ） 775 - 782 2021年12月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

Graphene quantum dots (GQDs) have emerged as a promising new class of environmentally friendly quantum dots with unique properties. However, the limitations of synthesis and patterning methods have hindered GQDs from displaying their true potentials to date. Here, we demonstrate the simultaneous synthesis and patterning of GQDs for the first time inside a transparent polymer, polydimethylsiloxane (PDMS), using femtosecond laser pulses. By focusing and scanning femtosecond laser pulses, arbitrary fluorescent patterns such as a concealed fluorescent QR code can be readily patterned without pre- and/or post-treatment. In addition, the proposed method is applied to the fabrication of fluorescent three-dimensional structures inside a transparent polymer via multiphoton interactions. The proposed method realizes single-stepped and spatially selective patterning of GQDs directly inside polymer substrates and expands the possibilities of GQDs for applications in novel flexible three-dimensional optoelectrical devices.

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Nanosecond laser ablation of AlN ceramic

N. Nedyalkov, A. Dikovska, L. Aleksandrov, M. Terakawa

Applied Physics A （Applied Physics A: Materials Science and Processing）  127 （ 12 ） 951 2021年11月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

In this work, the ablation rate and surface modifications are studied of aluminum nitride ceramic treated by a pulsed nanosecond Nd:YAG laser at four wavelengths—266 nm, 355 nm, 532 nm, and 1064 nm. The ablation depth is presented as a function of the laser fluence and the number of pulses applied. A decrease of the ablation efficiency with the increase of both laser fluence and number of pulses is observed for all wavelengths used. It is found that the laser treatment leads to the formation of a variety of micro and nanostructures on the surface of the material that are strongly dependent on the processing conditions. The laser ablation at the fundamental wavelength leads to the appearance of periodic structures on the surface. Such effect is not observed for the other wavelengths used. It is further found that the laser processing also leads to the formation a conductive layer for all wavelengths. Using a model based on the heat diffusion equation that takes into account the process of ceramic decomposition, the ablation dynamics is followed, and the dependence of the surface layers thickness on the processing conditions is estimated. The results obtained are used to explain the experimentally observed dependences.

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Pulsed laser deposition of plasmonic structures in air by irradiation through the substrate

Nedyalkov N., Nikov R., Nikov R., Dikovska A., Karashanova D., Grochowska K., Karczewski J., Śliwiński G., Terakawa M.

Thin Solid Films （Thin Solid Films）  734 2021年09月

研究論文（学術雑誌）, 共著, 査読有り

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Laser-induced periodic structure formation in AlN ceramic

Nedyalkov N.N., Dikovska A., Nikov R., Atanasova G., Hayashi S., Terakawa M.

Optics and Laser Technology （Optics and Laser Technology）  144 2021年07月

研究論文（学術雑誌）, 共著, 査読有り

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Laser direct writing of highly crystalline graphene on PDMS for fingertip-sized piezoelectric sensors

Shuichiro Hayashi, Fumiya Morosawa, Mitsuhiro Terakawa

Advanced Engineering Materials （Wiley）  23 （ 10 ） 2100457 2021年06月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

The patterning of electrically conductive structures directly onto the polydimethylsiloxane (PDMS) surface is crucial for the realization of flexible and elastic devices. Herein, defocused femtosecond laser pulses are irradiated for the fabrication of highly crystalline graphitic carbon structures on PDMS and a high electrical conductivity of ≈51.6 S m−1 is achieved. Utilizing the elasticity of PDMS and the high conductivity of fabricated structures, a fingertip-sized pressure sensor, which can detect pressures as low as ≈0.1 Pa, is realized. Moreover, a novel ring-shaped heart rate (HR) monitor, capable of measuring the HR from the index finger, is demonstrated, indicating the potential of fabricated structures in miniature and wearable healthcare applications.

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Electrically Conductive Porous Carbon Structures Fabricated by Laser Direct Carbonization of Bamboo

Miyakoshi R., Morosawa F., Hayashi S., Terakawa M.

2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021 （2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021）  2021年06月

　概要を見る

Porous carbon structures have attracted much interest for applications, such as catalyst carriers, energy storage devices, and chemical sensors, due to their chemical stability, high adsorptive property, and electrical conductivity. Among several methods to fabricate porous carbon structures, laser carbonization is a promising method for spatially-selective and high-resolution fabrication of electrically conductive porous carbon strucutres [1], [2]. Recently, the fabrication of porous carbon structures by laser carbonization using biomasses, materials derived from living or recently-living organisms, as the precursor have been reported [3]. In this study, we fabricated electrically conductive porous carbon structures by the femtosecond-laser carbonization of bamboo, which is a biomass with a well-connected three-dimensional porous structure by nature.

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Microfabrication of cellulose nanofiber-reinforced hydrogel by multiphoton polymerization

Hiroki Sugiyama, Kaneto Tsunemitsu, Hiroaki Onoe, Kotaro Obata, Koji Sugioka, Mitsuhiro Terakawa

Scientific Reports （Springer Nature）  11 （ 1 ） 10892 2021年05月

研究論文（学術雑誌）, 共著, 査読有り

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The mechanical strength of hydrogel microstructures is crucial for obtaining the desired flexibility, robustness, and biocompatibility for various applications such as cell scaffolds and soft microrobots. In this study, we demonstrate the fabrication of microstructures composed of cellulose nanofibers (CNFs) and poly(ethylene glycol) diacrylate (PEGDA) hydrogels by multiphoton polymerization. The stress of the fabricated microstructure during tensile testing increased with an increase in the CNF concentration, indicating that the mechanical strength of the microstructure was enhanced by using CNFs as fillers. Moreover, the swelling ratio of the microstructure increased with increasing CNF concentration in the PEGDA hydrogel. Our results show the potential of the technique for the microfabrication of advanced cell scaffolds and soft microrobots with the desired mechanical strength.

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Femtosecond laser-induced graphitization of transparent cellulose nanofiber films

Fumiya Morosawa, Shuichiro Hayashi, Mitsuhiro Terakawa

ACS Sustainable Chemistry & Engineering （ACS Sustainable Chemistry and Engineering）  9 （ 7 ） 2955 - 2961 2021年02月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2021 American Chemical Society. Laser graphitization allows for the spatially targeted modification of biomasses into electrically conductive structures and is a promising technique for the development of sustainable electronic devices. Out of the many biomasses, cellulose nanofiber (CNF) is a sustainable biomass which exhibits unique properties, such as mechanical strength and optical transparency. In this study, we demonstrated the fabrication of highly conductive graphitic carbon from CNFs using a high-repetition femtosecond laser. A conductivity as high as 6.9 S/cm was obtained by single scanning of the laser beam, which is estimated to be more than 100 times higher than the conductivity reported previously. From the Raman analysis of the structure, the formation of highly crystalline graphitic carbon was indicated, which contributes to the high conductivity. In the case of high-repetition femtosecond laser irradiation, it is considered that strong optical effects, in addition to thermal effects, contribute to the degradation of CNFs, resulting in the formation of highly crystalline graphitic carbon. Our presented technique allows for the direct writing of highly conductive graphitic carbon on CNF films, and the development of sustainable electronic devices, using mechanically robust and transparent CNF films as the substrate, should be realized.

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Charged fluorophores-assisted fabrication of metallic structures inside hydrogel by multi-photon photoreduction

Machida M., Shen W., Onoe H., Heisterkamp A., Mazur E., Terakawa M.

Proceedings of SPIE - The International Society for Optical Engineering （Proceedings of SPIE - The International Society for Optical Engineering）  11676 2021年

　概要を見る

We demonstrated the fabrication of gold microstructures inside a PEG-based hydrogel with different charged fluorophores by multi-photon photoreduction. By adding an anionic charged FITC-dextran or a cationic charged Rhodamine110 to the metal ion solution, line width of the fabricated gold microstructures increased compared to that of the structures fabricated in fluorophore-free hydrogel. The photobleaching could enhanced the reduction of gold ions accompanying the oxidation of the fluorophores. Notably, the inhibition of reduction of gold ions at a site other than the focal point was observed with FITC-dextran, which may be attributable to the coordination of gold ions to FITC-dextran.

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Fabrication of hollow channels surrounded by gold nanoparticles in hydrogel by femtosecond laser irradiation

Izumi Takayama, Akito Katayama, Mitsuhiro Terakawa

Nanomaterials （Nanomaterials）  10 （ 12 ） 2529 - 10 2020年12月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. The fabrication of hollow channels surrounded by gold nanoparticles in poly(ethylene glycol) diacrylate (PEGDA) is demonstrated. The absorption spectra show that gold nanoparticles were formed at the periphery of the focus by reduction of gold ions. The microscope observation and Raman spectroscopy analyses indicate that the center of the channels were void of PEGDA, which can be attributed to the femtosecond laser-induced degradation of the hydrogel. Since both the hydrogel and gold nanoparticles are biocompatible, this technique of fabricating hollow channels surrounded by gold nanoparticles is promising for tissue engineering, drug screening, and lab-on-a-chip devices.

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Anionic fluorophore-assisted fabrication of gold microstructures inside a hydrogel by multi-photon photoreduction

Manan Machida, Weilu Shen, Hiroaki Onoe, Yuki Hiruta, Alexander Heisterkamp, Eric Mazur, and Mitsuhiro Terakawa

Optical Materials Express （The Optical Society (OSA)）  11 （ 1 ） 48 - 58 2020年12月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2020 Optical Society of America. All Rights Reserved. The fabrication of accentuated gold microstructures is demonstrated by multi-photon photoreduction inside an anionic fluorophore-containing hydrogel. We attempted to facilitate gold-ion photoreduction near the focal point of laser pulses, expecting the donation of electrons by the oxidation of fluorophores in the vicinity of gold ions. The presence of anionic FITCdextran also inhibited the spontaneous reduction in untargeted zones, which is attributed to the coordination of gold ions and the anionic FITC-dextran. Simultaneous facilitation and inhibition are promising for the fabrication of dense metal microstructures in the targeted zone while maintaining the hydrogel's light permeability.

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Femtosecond-laser-induced graphitic carbon from transparent cellulose nanofiber films

Morosawa F., Hayashi S., Terakawa M.

2020 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2020 - Proceedings （2020 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2020 - Proceedings）  2020年08月

　概要を見る

© 2020 IEEE. The fabrication of electrically conductive structures by femtosecond-laser irradiation of a cellulose nanofiber (CNF) film was demonstrated. Raman analyses indicated the formation of graphitic carbon, which is attributable to the electrical conductivity of the structures.

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Multiphoton photoreduction for dual-wavelength-light-driven shrinkage and actuation in hydrogel

Kosuke Mizuguchi, Yo Nagano, Hiroaki Nishiyama, Hiroaki Onoe, Mitsuhiro Terakawa

Optical Materials Express （The Optical Society (OSA)）  10 （ 8 ） 1931 - 1940 2020年07月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. The dual-wavelength-driven shrinkage of metal microstructures and hydrogel actuation are demonstrated by the fabrication of multi-metal microstructures in hydrogels by multiphoton photoreduction. Silver and gold microstructures were fabricated in a poly-Nisopropylacrylamide (PNIPAm) hydrogel. Because of the different optical resonances of the metals, wavelength-dependent shrinkage of metal microstructures was demonstrated concurrently with the volume change of the supporting hydrogel by light stimulation. Furthermore, the direction of actuation of the hydrogel was controlled by switching the wavelength of light stimulation. The results indicate the potential of multiphoton photoreduction for applications in light-driven optical components and micro-robots fabricated with soft materials.

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Myoblast adhesion and proliferation on biodegradable polymer films with femtosecond laser-fabricated micro through-holes

Takayama I., Kondo N., Kalies S., Heisterkamp A., Terakawa M.

Journal of Biophotonics （Journal of Biophotonics）  13 （ 7 ）  2020年04月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Controlling cell adhesion and cell differentiation is necessary to fabricate a tissue with arbitrary properties for tissue engineering applications. A substrate with a porous structure as a cell scaffold allows the diffusion of the cell culture medium through the scaffold. In this work, we show that the femtosecond laser fabricated micro through-holes in biodegradable polymer films, enhance myoblast adhesion, and accelerates proliferation and differentiation. ChR2-C2C12 and UT-C2C12 cells were seeded on the films with micro through-holes each fabricated by a single femtosecond laser pulse. Cell adhesion was enhanced on films with holes fabricated by laser irradiation. In addition, cell proliferation was accelerated on films with micro through-holes that penetrate the film, compared to on films with micro craters that do not penetrate the film. On films with arrays consisting of micro through-holes, cells aligned along the arrays and cell fusion was enhanced, indicating the acceleration of cell differentiation.

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Synthesis of silicon carbide nanocrystals and multilayer graphitic carbon by femtosecond laser irradiation of polydimethylsiloxane

Hayashi S., Morosawa F., Terakawa M.

Nanoscale Advances （Nanoscale Advances）  2 （ 5 ） 1886 - 1893 2020年03月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© The Royal Society of Chemistry 2020. Laser-based modification of polymer materials has been emerging as a versatile and efficient technique to simultaneously form and pattern electrically conductive materials. Recently, it has been revealed that native polydimethylsiloxane (PDMS) can be modified into electrically conductive structures using femtosecond laser irradiation; however, the details regarding the structures formed by this method have yet to be revealed. In this work, structures were fabricated by focusing and scanning femtosecond laser pulses onto the surface of PDMS. Raman Spectroscopy and Transmission Electron Microscopy (TEM) analyses revealed the formation of silicon carbide (SiC) nanocrystals, as well as multilayer graphitic carbon, in the modified regions of PDMS. The state of the formed material differed depending on the distance from the focal spot, suggesting that photo-thermal effects contributed to the degradation of PDMS into conductive material. Electrical conductivity measurements, in addition to Raman results, indicated that the amount of disorder in the formed graphitic carbon contributes to the electrical conductivity of the fabricated structures.

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Effect of Pd-decoration on the sensing properties of ZnO nanostructures

Dilova T., Atanasova G., Og. Dikovska A., Avdeev G., Machida M., Terakawa M., Stefanov P., Nedyalkov N.

Thin Solid Films （Thin Solid Films）  693   137693 2020年01月

　概要を見る

© 2019 Elsevier B.V. In this work, we present fabrication and studies of pure and Pd-decorated ZnO nanostructures on Ag-coated substrates in view of gas-sensing application. The sensor elements consist of a dense structure of ZnO nanobelts. The chemical composition of the surface and gas-sensing properties of pure and Pd-doped nanostructures were studied and compared. On the surface of the Pd-decorated ZnO samples, the presence was found of Pd and Pd-Ag clusters, as well as isolated Pd2+ ions were incorporated into the ZnO lattice. The Pd-ZnO sensor element showed a better response to CO, NH3, and acetone compared to the pure ZnO sample. The Pd-ZnO sample exhibited its highest response to exposure to acetone at room temperature. We associate the improvement of sensing performance of the Pd-decorated ZnO nanostructures with the increased number of adsorption centers on the surface due to the Pd nanoparticles.

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Luminescence properties of laser-induced silver clusters in borosilicate glass

Nedyalkov N., Dikovska A., Koleva M., Stankova N., Nikov R., Borisova E., Genova T., Aleksandrov L., Iordanova R., Terakawa M.

Optical Materials （Optical Materials）  100 2019年12月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2019 Elsevier B.V. This paper describes the luminescence properties of small silver clusters formed by laser treatment of silver-doped borosilicate glass. Using irradiation by a Nd:YAG nanosecond laser system operating at the fourth harmonic wavelength (266 nm), areas are formed in the glass samples that emit bright luminescence peaking at about 600 nm when excited by UV light in the spectral range 300–390 nm. The influence is presented and discussed of the glass composition and the laser processing parameters on the emission characteristics. It is further shown that the luminescent properties are affected by the fluence of the excitation source, namely, a complete quenching of the emission is achieved above a certain value. The luminescence of the irradiated areas is explained by the formation of Ag clusters due to irradiation-induced reduction of Ag ions and increased atom mobility resulting from the local heating. The limited stability of the luminescent areas upon UV radiation can be related to heat-induced cluster decomposition and re-oxidation. The results obtained provide a new insight in the optical properties of noble-metal nanostructures and could form the basis of fabrication of complex optical systems and luminescent component used in the study of, e.g., biological systems.

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Fabrication of a monolithic lab-on-a-chip platform with integrated hydrogel waveguides for chemical sensing

Torres-Mapa M., Singh M., Simon O., Mapa J., Machida M., Günther A., Roth B., Heinemann D., Terakawa M., Heisterkamp A.

Sensors (Switzerland) （Sensors (Switzerland)）  19 （ 19 ）  2019年10月

　概要を見る

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. Hydrogel waveguides have found increased use for variety of applications where biocompatibility and flexibility are important. In this work, we demonstrate the use of polyethylene glycol diacrylate (PEGDA) waveguides to realize a monolithic lab-on-a-chip device. We performed a comprehensive study on the swelling and optical properties for different chain lengths and concentrations in order to realize an integrated biocompatible waveguide in a microfluidic device for chemical sensing. Waveguiding properties of PEGDA hydrogel were used to guide excitation light into a microfluidic channel to measure the fluorescence emission profile of rhodamine 6G as well as collect the fluorescence signal from the same device. Overall, this work shows the potential of hydrogel waveguides to facilitate delivery and collection of optical signals for potential use in wearable and implantable lab-on-a-chip devices.

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Fabrication of metal microstructures in elastic hydrogel by multiphoton photoreduction

Terakawa M., Machida M., Onoe H., Niidome T., Heisterkamp A.

2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019 （2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019）  Part F140-CLEO_Europe 2019 2019年06月

　概要を見る

© 2019 IEEE. Soft materials, including elastic polymers and hydrogels, are promising materials for soft robots, implantable devices, and wearable devices owing to their flexibility and biocompatibility. In recent years, the scope of use of such soft materials is expanding further because of their integration with metal micro- and nanostructures, which exhibit attractive optical and electrical properties. In this study, we demonstrate the formation of metal microstructures inside a hydrogel by photoreduction of metal ion by using femtosecond laser. Because the hydrogels have permeability to fluids, metal ions are able to be added by simply immersing the hydrogel into the metal ion solution. Femtosecond laser pulses were focused and scanned in the hydrogel to fabricate metal microstructures [1, 2]. The optical diffraction pattern obtained with the silver grating inside the hydrogel showed spaced diffraction spots, which indicated that a regular, periodic silver grating was formed. Notably, the distance between the diffraction spots changed when the water content in the hydrogel was reduced. The grating period decreased when the hydrogel shrank owing to the loss of water (Fig. 1(a)), but the straight shapes of the line structures were preserved, which demonstrated the optical tunability of the fabricated structure.

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Strain sensing using electrically conductive structures fabricated by femtosecond-laser-based modification of PDMS

Hayashi S., Nakajima Y., Terakawa M.

Optical Materials Express （Optical Materials Express）  9 （ 6 ） 2672 - 2680 2019年05月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2019 Optical Society of America. Strain sensing was demonstrated by utilizing electrically conductive silicon-carbide (β-SiC) fabricated by femtosecond-laser-based direct modification of polydimethylsiloxane (PDMS). Depending on the laser scanning direction used for the fabrication procedure, the fabricated structures showed different sensitivity to strain and this difference was discussed by observing the surface morphology at various bending radii using scanning electron microscopy (SEM). The change in electrical conductance at the flat state after repeated bending was also investigated. Furthermore, preliminary demonstration of human motion sensing was performed using the fabricated structures. The presented method will open doors to novel electronic device applications using PDMS.

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Spatially-targeted laser fabrication of multi-metal microstructures inside a hydrogel

Machida M., Niidome T., Onoe H., Heisterkamp A., Terakawa M.

Optics Express （Optics Express）  27 （ 10 ） 14657 - 14666 2019年05月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement The spatially-targeted fabrication of bimetallic microstructures coexisting in the supporting hydrogel is demonstrated by multi-photon photoreduction. Microstructures composed of gold and silver were fabricated along a predefined trajectory by taking advantages of the hydrogel's ionic permeability. Different resonant wavelengths of optical absorption were obtained for gold, silver, and their bimetallic structures. Transmission electron microscopy and energy dispersive X-ray analysis revealed that the optical properties are attributable to the formation of bimetallic structure consisted of core-shell nanoparticles. The fabrication of dissimilar metal structures within hydrogel is a promising technique for optically driven actuators in soft robotics and sensing applications by allowing for site-selective optical properties.

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Photoacoustic diagnosis of pharmacokinetics and vascular shutdown effects in photodynamic treatment with indocyanine green-lactosome for a subcutaneous tumor in mice

Tsunoi Y., Araki K., Ozeki E., Hara I., Shiotani A., Terakawa M., Sato S.

Photodiagnosis and Photodynamic Therapy （Photodiagnosis and Photodynamic Therapy）  26   436 - 441 2019年05月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2019 Indocyanine green lactosome (ICG-lactosome) is an attractive new-generation agent for photodynamic therapy (PDT) that is characterized by a near-infrared excitation wavelength and high stability in the bloodstream. Fluorescence imaging has been used to examine its pharmacokinetics in vivo, but no depth-resolved information can be obtained with this method. In this study, we applied photoacoustic (PA) imaging to visualize the depth distribution of ICG-lactosome in a mouse subcutaneous tumor model. With this method, the depth distribution of blood vessels can also be visualized, enabling detection of vascular shutdown effects due to PDT. We performed PA imaging of both the distributions of ICG-lactosome and blood vessels in a tumor before and after PDT, and we found that PA signals originating from ICG-lactosome were greatly increased at 18 h after drug injection but rapidly decreased after PDT. These results indicate efficient accumulation of ICG-lactosome and rapid photobleaching due to the PDT reaction in the tumor, respectively. After PDT, PA amplitudes of hemoglobin were significantly decreased, being attributable to vascular shutdown effects. These results show the usefulness of PA imaging for monitoring not only photosensitizer accumulation and bleaching but also vascular responses in PDT with ICG-lactosome. This method can be applied to the diagnosis of many types of PDT processes.

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Hybrid UV laser direct writing of UV-curable PDMS thin film using aerosol jet printing

Hohnholz A., Obata K., Nakajima Y., Koch J., Terakawa M., Suttmann O., Overmeyer L.

Applied Physics A: Materials Science and Processing （Springer）  125 （ 2 ）  2019年02月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. Polydimethylsiloxane (PDMS) is widely used for bio-medical, optical and microfluidic applications. Hence, PDMS layers on free-form surfaces on defined areas are needed. Conventional ways such as spin coating show drawbacks by long processing time and no sufficient application on free form surfaces. In this work, laser direct writing with UV-curable PDMS on a curved surface was performed. The coating technique using aerosol jet printing showed thin film thicknesses, compared to conventional spin coating techniques, obtaining controllable layer thickness down to 3.5 µm in 5 min on an area of 600 mm 2 and on non-flat surfaces. Deposition rate control achieved layer thicknesses between 3.5 and 25.7 µm. The combination of material deposition and x–y galvanometric mirror scanner-based laser direct writing leads to a hybrid approach aiming for several applications in the fields of surface functionalization, and bio-medical and sensory applications. In addition, the procedure is able to overcome the batch-based PDMS processing and introduce the continuous flow-based application.

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Biodegradability of poly(lactic-co-glycolic acid) irradiated with femtosecond laser pulses without material removal

Kondo N., Terakawa M.

Applied Physics A: Materials Science and Processing （Applied Physics A: Materials Science and Processing）  125 （ 2 ）  2019年

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. The degradation rates of biodegradable polymers are necessary to be controlled for tissue scaffold applications. In this work, we demonstrate that the degradation rate of poly(lactic-co-glycolic acid) (PLGA) was accelerated by irradiating with femtosecond laser pulses under the condition where material removal, i.e., laser ablation had not occurred. Scanning electron microscopy observation showed that the degradation rate was accelerated without significant laser ablation. The analysis of Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed that the chemical properties of the PLGA had changed by femtosecond laser pulses irradiation. Furthermore, we have investigated the degradation of PLGA when the femtosecond laser pulses were focused inside the material. After the degradation, the PLGA showed enhanced optical scattering region in the depth of 300 µm from the surface. The results indicate that high-aspect-ratio modification and degradation are possible by changing the depth of focus of femtosecond laser pulses under the conditions where the direct removal of the material was not occurred.

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Surface-Enhanced Raman Spectroscopy (SERS) of Mancozeb and Thiamethoxam Assisted by Gold and Silver Nanostructures Produced by Laser Techniques on Paper

Atanasov P., Nedyalkov N., Fukata N., Jevasuwan W., Subramani T., Terakawa M., Nakajima Y.

Applied Spectroscopy （Applied Spectroscopy）  73 （ 3 ） 313 - 319 2019年

研究論文（学術雑誌）, 単著, 査読有り

　概要を見る

© The Author(s) 2018. Advanced gold (Au) and silver (Ag) nanostructures were produced by laser techniques on printer paper substrate. Surface-enhanced Raman spectroscopy (SERS) analyses of the fungicide mancozeb (Dithane DG) and insecticide thiamethoxam (Aktara 25 BG) in quantities smaller than usually applied in agricultural medicine were performed for the first time assisted by the structures fabricated. The investigations and results show an easy alternative and cheap way to detect small amounts or residue of harmful environmental pollutants, which has a direct bearing on food quality and thus on human health.

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Direct laser writing of Ag nanoparticle-composed structures in glass

Nedyalkov N., Koleva M., Stankova N., Nikov R., Atanasov P., Aleksandrov L., Iordanova R., Sliwinski G., Sawczak M., Grochowska K., Terakawa M.

Proceedings of SPIE - The International Society for Optical Engineering （Proceedings of SPIE - The International Society for Optical Engineering）  11047 2019年

研究論文（国際会議プロシーディングス）

　概要を見る

© 2019 SPIE. In this work results on laser assisted formation of silver nanoparticles in glass are presented. The sample material used in the experiments is Ag doped borosilicate glass fabricated by conventional melt quenching method. The glass samples are irradiated by nanosecond laser pulses at wavelength of 266 nm with a wide range of fluences and number of applied pulses. It is found that the laser radiation can lead to specific yellow coloration of the irradiated areas. The performed analyses show formation of silver nanoparticles in these zones. The optical properties of the irradiated areas are found to depend on the laser processing parameters and the silver concentration. The mechanism of nanoparticle formation is also discussed. The presented method can be used for formation of nanoparticles inside transparent materials and can be used for fabrication of novel materials with application in photonics.

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Femtosecond laser-based formation of electrically conductive silicon carbide on PDMS

Nakajima Y., Hayashi S., Katayama A., Nedyalkov N., Terakawa M.

Proceedings of SPIE - The International Society for Optical Engineering （Proceedings of SPIE - The International Society for Optical Engineering）  10908 2019年

　概要を見る

Copyright © 2019 SPIE. We experimentally demonstrated formation of electrically conductive structures by modifying native polydimethylsiloxane (PDMS) with femtosecond laser. By irradiating femtosecond laser pulses to native PDMS, black structures with electrical conductivity were formed. Analyses using X-ray diffraction (XRD) show that the formed structures were composed of β-silicon carbide (β-SiC). Our technique enables the spatially selective formation of β-SiC on the surface of PDMS, leading to open a novel route to develop a simple method to fabricate flexible or stretchable MEMS devices with SiC microstructures.

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Strain sensing using electrically conductive structures composed of β-SiC fabricated by femtosecond laser direct modification of PDMS

Hayashi S., Nakajima Y., Terakawa M.

Proceedings of SPIE - The International Society for Optical Engineering （Proceedings of SPIE - The International Society for Optical Engineering）  10905 2019年

　概要を見る

© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. By femtosecond-laser-based modification of polydimethylsiloxane (PDMS), we fabricated an electrically conductive structure composed of β-silicon carbide (β-SiC) on a PDMS thin film for strain sensing. With an increase in applied strain, i.e. smaller bend radii of the conductive structures, the conductivity of the structure decreased significantly. The result indicates that the resistance of the conductive structure has high sensitivity to strain, leading to potential applications such as real-time monitoring of human motion.

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Quality improvement of acoustic-resolution photoacoustic imaging of skin vasculature based on practical synthetic-aperture focusing and bandpass filtering

Tsunoi Y., Yoshimi K., Watanabe R., Kumai N., Terakawa M., Sato S.

Japanese Journal of Applied Physics （Japanese Journal of Applied Physics）  57 （ 12 ） 127001 2018年11月

研究論文（学術雑誌）, 単著, 査読有り

　概要を見る

© 2018 The Japan Society of Applied Physics. We previously developed a compact acoustic-resolution photoacoustic (PA) imaging system with optical fiber-based illumination, by which blood vessels in the rat skin were visualized in vivo. However, there were issues to be improved in the imaging characteristics: blurring in the out-of-focus region of the ultrasound sensor and degraded resolution due to low-frequency components in the PA signals. These are common limitations in acoustic-resolution PA imaging methods. In this study, we attempted to solve these problems by introducing signal processing methods based both on the synthetic-aperture focusing technique, which was applied only to signals in the detection zone of the sensor in the horizontal direction that was determined in advance in a phantom study, and on digital acoustic signal filtering with three specific frequency bands. Ex vivo and in vivo PA imaging of blood vessels in the rat skin and subcutaneous tissue showed the validity of the present signal processing methods.

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Femtosecond laser-based modification of PDMS to electrically conductive silicon carbide

Nakajima Y., Hayashi S., Katayama A., Nedyalkov N., Terakawa M.

Nanomaterials （Nanomaterials）  8 （ 7 ） 558 2018年07月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. In this paper, we experimentally demonstrate femtosecond laser direct writing of conductive structures on the surface of native polydimethylsiloxane (PDMS). Irradiation of femtosecond laser pulses modified the PDMS to black structures, which exhibit electrical conductivity. Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) results show that the black structures were composed of β-silicon carbide (β-SiC), which can be attributed to the pyrolysis of the PDMS. The electrical conductivity was exhibited in limited laser power and scanning speed conditions. The technique we present enables the spatially selective formation of β-SiC on the surface of native PDMS only by irradiation of femtosecond laser pulses. Furthermore, this technique has the potential to open a novel route to simply fabricate flexible/stretchable MEMS devices with SiC microstructures.

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Femtosecond laser processing of biodegradable polymers

Terakawa M.

Applied Sciences (Switzerland) （Applied Sciences (Switzerland)）  8 （ 7 ） 1123 2018年07月

研究論文（学術雑誌）, 単著, 査読有り

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© 2018 by the authors. Biodegradable polymers have attracted increasing attention in tissue engineering and drug delivery systems owing to their high biocompatibility and biodegradability. Among the various methods for shape forming and modification of biodegradable polymers, laser processing has advantages in a dry processing approach that can process complex-shaped surfaces without using toxic chemical components. This review provides an overview of femtosecond laser processing of biodegradable polymers, especially in the last decade. The interaction mechanism of femtosecond laser pulse and biodegradable polymers, e.g., bond dissociation after laser irradiation, affects the degradable property of biodegradable polymers, which has the potential to control the degradation and sustainability of a structure. Applied studies on controlling cell behavior, tissue scaffolding, and drug release are also described.

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Gold nanoparticle-mediated laser stimulation induces a complex stress response in neuronal cells

Johannsmeier S., Heeger P., Terakawa M., Kalies S., Heisterkamp A., Ripken T., Heinemann D.

Scientific Reports （Scientific Reports）  8 （ 1 ） 6533 2018年04月

研究論文（学術雑誌）, 共著, 査読有り

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© 2018 The Author(s). Stimulation of neuronal cells generally resorts to electric signals. Recent advances in laser-based stimulation methods could present an alternative with superior spatiotemporal resolution. The avoidance of electronic crosstalk makes these methods attractive for in vivo therapeutic application. In particular, nano-mediators, such as gold nanoparticles, can be used to transfer the energy from a laser pulse to the cell membrane and subsequently activate excitable cells. Although the underlying mechanisms of neuronal activation have been widely unraveled, the overall effect on the targeted cell is not understood. Little is known about the physiological and pathophysiological impact of a laser pulse targeted onto nanoabsorbers on the cell membrane. Here, we analyzed the reaction of the neuronal murine cell line Neuro-2A and murine primary cortical neurons to gold nanoparticle mediated laser stimulation. Our study reveals a severe, complex and cell-type independent stress response after laser irradiation, emphasizing the need for a thorough assessment of this approach's efficacy and safety.

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Shrinkable silver diffraction grating fabricated inside a hydrogel using 522-nm femtosecond laser

Machida M., Nakajima Y., Torres-Mapa M., Heinemann D., Heisterkamp A., Terakawa M.

Scientific Reports （Scientific Reports）  8 （ 1 ） 187 2018年01月

研究論文（学術雑誌）, 共著, 査読有り

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© 2017 The Author(s). The integration of metal microstructures and soft materials is promising for the realization of novel optical and biomedical devices owing to the flexibility and biocompatibility of the latter. Nevertheless, the fabrication of three-dimensional metal structures within a soft material is still challenging. In this study, we demonstrate the fabrication of a silver diffraction grating inside a biocompatible poly(ethylene glycol) diacrylate (PEGDA) hydrogel by using a 522-nm femtosecond laser via multi-photon photoreduction of silver ions. The optical diffraction pattern obtained with the grating showed equally spaced diffraction spots, which indicated that a regular, periodic silver grating was formed. Notably, the distance between the diffraction spots changed when the water content in the hydrogel was reduced. The grating period decreased when the hydrogel shrank owing to the loss of water, but the straight shapes of the line structures were preserved, which demonstrated the optical tunability of the fabricated structure. Our results demonstrate the potential of the femtosecond laser-based photoreduction technique for the fabrication of novel tunable optical devices as well as highly precise structures.

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Femtosecond laser-triggered molecular release from biodegradable polymer microcapsules incorporated in gelatin hydrogel

Umemoto T., Terakawa M.

Proceedings of SPIE - The International Society for Optical Engineering （Proceedings of SPIE - The International Society for Optical Engineering）  10522 2018年

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© COPYRIGHT SPIE. Stimuli-responsible controlled release of growth factors from a tissue scaffold has gained significant interest for efficient tissue engineering. Laser-triggered methods for the molecular release have the advantage of spatial and temporal controllability. In this study, we demonstrate laser-triggered molecular release from biodegradable polymer microcapsules incorporated in gelatin hydrogel for the aim of efficient tissue engineering. The microcapsules, which fluorescent molecules were encapsulated, were fabricated using a dual-coaxial nozzle system. The microcapsule suspension was mixed with gelatin solution, followed by cross-linking to fabricate a gelatin hydrogel. Femtosecond laser pulses were focused onto the hydrogel to release fluorescent molecules from the microcapsules in the gelatin hydrogel.

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Intracellular localization and delivery of plasmid DNA by biodegradable microsphere-mediated femtosecond laser optoporation

A. Ishii, Y. Hiruta, D. Heinemann, A. Heisterkamp, H. Kanazawa, M. Terakawa

Journal of Biophotonics 10 （ 12 ） 1723 - 1731 2017年12月

研究論文（学術雑誌）, 共著, 査読有り

Laser-assisted fabrication of gold nanoparticle-composed structures embedded in borosilicate glass

Nikolay Nedyalkov, Mihaela Koleva, Nadya Stankova, Rosen Nikov, Mitsuhiro Terakawa, Yasutaka Nakajima, Lyubomir Aleksandrov, Reni Iordanova

The Beilstein Journal of Nanotechnology 8   2454 - 2463 2017年11月

研究論文（学術雑誌）, 共著, 査読有り

Femtosecond-laser-based fabrication of metal/PDMS composite microstructures for mechanical force sensing

Y. Nakajima, K. Obata, M. Machida, A. Hornholz, J. Koch, O. Suttmann, M. Terakawa

Optical Materials Express （The Optical Society (OSA)）  7 （ 11 ） 4203 - 4213 2017年11月

研究論文（学術雑誌）, 共著, 査読有り

Effects of pulsed laser irradiation on gold-coated silver nanoplates and their antibacterial activity

K. Kyaw, H. Ichimaru, T. Kawagoe, M. Terakawa, Y. Miyazawa, D. Mizoguchi, M. Tsushida, T. Niidome

Nanoscale （Royal Society of Chemistry）  9 （ 41 ） 16101 - 16105 2017年10月

研究論文（学術雑誌）, 共著, 査読有り

UV Laser Photo-Polymerization of Elastic 2D/3D Structures Using Photo-Curable PDMS (Polydimethylsiloxane)

O. Suttmann, K. Obata, Y. Nakajima, A. Hohnholz, J. Koch, M. Terakawa, L. Overmeyer

Journal of Laser Micro/Nanoengineering 12 （ 2 ） 153 - 158 2017年09月

研究論文（学術雑誌）, 共著, 査読有り

Formation of gold grating structures on fused silica substrates by femtosecond laser irradiation

A. Takami, Y. Nakajima, M. Terakawa

Journal of Applied Physics 121   173103/1 - 5 2017年05月

研究論文（学術雑誌）, 共著, 査読有り

Biodegradability of poly(lactic-co-glycolic acid) and poly(L-lactic acid) after deep-ultraviolet femtosecond and nanosecond laser irradiation

A. Shibata, M. Machida, N. Kondo, M. Terakawa

Applied Physics A 123   438 2017年05月

研究論文（学術雑誌）, 共著, 査読有り

Nanofabrication of high throughput 20 nm hole 2D arrays by a simple visible laser ablation technique

Kazushi Yamada, Chieko Narita, Ramanujam Kumaresan, Takuya Shinohara, Mitsuhiro Terakawa, Yasuyuki Tsuboi

Applied Surface Science 420   868 - 872 2017年05月

研究論文（学術雑誌）, 共著, 査読有り

Gold nanostructures deposition by laser ablation in air using nano- and femtosecond laser pulses

N. Nedyalkov, R. Nikov, A. Dikovska, G. Atanasov, Y. Nakajima, M. Terakawa

Applied Physics A 123 （ 5 ） 1 - 11 2017年04月

研究論文（学術雑誌）, 共著, 査読有り

Fabrication of isolated platinum nanowire gratings and nanoparticles on silica substrate by femtosecond laser irradiation

Y. Nakajima, N. Nedyalkov, A. Takami, M. Terakawa

Applied Surface Science （Elsevier）  394   108 - 114 2017年02月

研究論文（学術雑誌）, 共著, 査読有り

Femtosecond laser irradiation of the fluorescent molecules-loaded poly(lactic-co-glycolic acid)

T. Umemoto, A. Shibata, M. Terakawa

Applied Surface Science 417   165 - 169 2017年02月

研究論文（学術雑誌）, 共著, 査読有り

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The influence of the thermal diffusivity of the substrates on fabrication of metal nanostructures by femtosecond laser irradiation

A. Takami, Y. Nakajima, N. Nedyalkov, M. Terakawa

Applied Physics A （Springer）  123 （ 126 ）  2017年01月

研究論文（学術雑誌）, 単著, 査読有り

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Laser-triggered release of encapsulated molecules from polylactic-co-glycolic acid microcapsules

K. Ariyasu, A. Ishii, T. Umemoto, M. Terakawa

Journal of Biomedical Optics （SPIE）  21 （ 8 ） 85003 2016年08月

研究論文（学術雑誌）, 共著, 査読有り

Biodegradability of poly(lactic-co-glycolic acid) after femtosecond laser irradiation

A. Shibata, S. Yada, M. Terakawa

Scientific Reports 6   27884 2016年06月

研究論文（学術雑誌）, 共著, 査読有り

Laser nanostructuring of ZnO thin films

N. Nedyalkov, Mihaela Emilova Koleva, Ru. Nikov, P. Atanasov, Y. Nakajima, A. Takami, A. Shibata, M. Terakawa

Applied Surface Science 374   172 - 176 2016年06月

研究論文（学術雑誌）, 共著, 査読有り

Biodegradable-microsphere mediated cell perforation in microfluidic channel using femtosecond laser

A. Ishii, K. Ariyasu, T. Mitsuhashi, D. Heinamann, A. Heisterkamp, M. Terakawa

Journal of Biomedical Optics 21 （ 5 ） 055001 2016年05月

研究論文（学術雑誌）, 共著, 査読有り

Femtosecond laser direct writing of metal microstructure in a stretchable poly(ethylene glycol) diacrylate (PEGDA) hydrogel

M. Terakawa, M. L. Torres-Mapa, A. Takami, D. Heinemann, N. N. Nedyalkov, Y. Nakajima, A. Hördt, T. Ripken, A. Heisterkamp

Optics Letters （OSA）  41 （ 7 ） 1392 - 1395 2016年04月

研究論文（学術雑誌）, 共著, 査読有り

Magnetic nanoparticle composed nanowires fabricated by ultrashort laser ablation in air

N. Nedyalkov,Y. Nakajima,M. Terakawa

Applied Physics Letters 108   043107 2016年01月

研究論文（学術雑誌）, 共著, 査読有り

Laser induced morphological and optical properties changes in Au doped aluminum oxide and silicon oxide thin films

N.N. Nedyalkov, Y. Nakajima, A. Takami, M. Koleva, D. Karashanova, M. Terakawa

Optics & Laser Technology （Elsevier）  79   179 - 187 2015年12月

研究論文（学術雑誌）, 共著, 査読有り

Theranostic system for drug delivery and pharmacokinetic imaging based on nanosecond pulsed light-induced photomechanical and photoacoustic effects

Y. Tsunoi, S. Sato, S. Kawauchi, Y. Akutsu, Y. Miyagawa, K. Araki, A. Shiotani, M. Terakawa

Jpn. J. Appl. Phys. 54 （ 11 ） 116601 2015年10月

研究論文（学術雑誌）, 共著, 査読有り

Reverse design of a bull’s eye structure for oblique incidence and wider angular transmission efficiency

A. Yamada, M. Terakawa

Applied Optics 54 （ 11 ） 3517 - 3522 2015年04月

研究論文（学術雑誌）, 共著, 査読有り

Formation of periodic metal nanowire grating on silica Substrate by femtosecond laser irradiation

Yasutaka Nakajima, Nikolay Nedyalkov, Akihiro Takami, Mitsuhiro Terakawa

Applied Physics A （Springer）  119   1215 - 1221 2015年04月

研究論文（学術雑誌）, 共著, 査読有り

Femtosecond laser induced periodic surface structure on poly-L-lactic acid

S. Yada, M. Terakawa

Optics Express 5   5694 - 5703 2015年02月

研究論文（学術雑誌）, 共著, 査読有り

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Compact acoustic-resolution photoacoustic imaging system with fiber-based illumination

Y. Tsunoi, S. Sato, R. Watanabe, S. Kawauchi, H. Ashida, M. Terakawa

Jpn. J. Appl. Phys. 53 （ 12 ） 126701 2014年11月

研究論文（学術雑誌）, 共著, 査読有り

Contribution of defect on early stage of LIPSS formation

H. Shimizu, S. Yada, G. Obara, M. Terakawa

Optics Express （OSA）  22 （ 15 ） 7990 - 7998 2014年07月

研究論文（学術雑誌）, 共著, 査読有り

Noble metallic nanostructures: preparation, properties, applications

P. A. Atanasov, N. N.. Nedyalkov, A. Og Dikovska, R. Nikov, S. Amoruso, X. Wang, R. Bruzzese, K. Hirano, H. Shimizu, M. Terakawa, M. Obara

Journal of Physics （IOP Publishing）  514   012024/1 - 012024/8 2014年05月

研究論文（学術雑誌）, 共著, 査読有り

Electron excitation effect on scattering near-field and far-field ablation material processing by femtosecond laser irradiation

T. Enami, G. Obara, M. Terakawa, M. Obara

Appl. Phys. A 114   253-259 2014年

研究論文（学術雑誌）, 共著, 査読有り

Evaluation of parameters influencing the molecular delivery by biodegradable microsphere-mediated perforation using femtosecond laser

T. Mitsuhashi, M. Terakawa

J. Biomed. Opt. 19   015003 2014年

研究論文（学術雑誌）, 共著, 査読有り

Nanostructured Ag/ZnO multilayer plasmonic composites

M. E. Koleva, N. N. Nedyalkov, A. OG.T.Dikovska, P. A. Atanasov, G. V. Avdeev, H. Shimizu, M. Terakawa, M. Obara, D. Pallotti, E. Orabona, P. Maddalena, S. Lettieri

Journal of Optoelectronics and Advanced Materials 16   144-148 2014年

研究論文（学術雑誌）, 共著, 査読有り

Gold nanosphere propulsion by using femtosecond laser-excited enhanced near field

T. Shinohara, M. Terakawa

Appl. Phys. A 116   1025 - 1031 2014年

研究論文（学術雑誌）, 共著, 査読有り

Nanostructured Au film produced by pulsed laser deposition in air at atmospheric pressure

N. Nedyalkov, A. Nikolov, P. Atanasov, M. Alexandrov, M. Terakawa, H. Shimizu

Optics & Laser Technology （Elsevier）  64   41 - 45 2014年

研究論文（学術雑誌）, 共著

High site-selective transvascular drug delivery by the use of nanosecond pulsed laser-induced photomechanical waves

S. Sato, K. Yoshida, S. Kawauchi, K. Hosoe, Y. Akutsu, N. Fujimoto, H. Nawashiro, M. Terakawa

Journal of Controlled Release 192   228 - 235 2014年

研究論文（学術雑誌）, 共著, 査読有り

Evolution of femtosecond laser-induced surface ripples on lithium niobate crystal surfaces

H. Shimizu, G. Obara, M. Terakawa, M. Obara

Appl. Phys. Exp. 6   112701/1-3 2013年11月

研究論文（学術雑誌）, 共著, 査読有り

Growth of high spatial frequency periodic ripple structures on SiC crystal surfaces irradiated with successive femtosecond laser pulses

G. Obara, H. Shimizu, T. Enami, E. Mazur, M. Terakawa, M. Obara

Opt. Exp. 21   26323-26334 2013年10月

研究論文（学術雑誌）, 共著

Plasmonic nanometric optical tweezers in an asymmetric space of gold nanostructured substrates

K. Hirano, H. Shimizu, T. Enami, M. Terakawa, M. Obara, N. N. Nedyalkov, P. A. Atanasov

Journal of Nanotechnology in Diagnosis and Treatment 1   2-10 2013年08月

研究論文（学術雑誌）, 共著, 査読有り

"Near-infrared femtosecond laser-triggered nanoperforation of hollow microcapsules"

M. Terakawa, T. Mitsuhashi, T. Shinohara, H. Shimizu

Optics Express 21   12604-12610 2013年06月

研究論文（学術雑誌）, 共著, 査読有り

Tuning the optical properties of gold nanostructures fabricated on flexiblesubstrates

R. Nikov, N. Nedyalkov, P. A. Atanasov, M. Terakawa, H. Shimizu, M. Obara

Appl. Surf. Sci. 264   779 2013年05月

研究論文（学術雑誌）, 共著, 査読有り

Photocatalytic nano-optical trapping using TiO2 nanosphere pairsmediated with Mie scattered near-field

T. Honda, M. Terakawa, M. Obara

Appl. Phys. B 111   117-126 2013年01月

研究論文（学術雑誌）, 共著

In vivo photoacoustic molecular imaging of the distribution of serum albumin in rat burned skin

Y. Tsunoi, S. Sato, S. Kawauchi, H. Ashida, D. Saitoh, M. Terakawa

Burns 39   1403-1408 2013年

研究論文（学術雑誌）, 共著, 査読有り

Reverse design of a bull’s eye structure based on the plasmonic far-field pattern

A. Yamada, M. Terakawa

Optics Express 21   21273-21284 2013年

研究論文（学術雑誌）, 共著, 査読有り

In vitro perforation of human epithelial carcinoma cell with antibody-conjugated biodegradable microspheres illuminated by a single 80 fs near-infrared laser pulse

M. Terakawa, Y. Tsunoi, T. Mitsuhashi

Int. J. Nanomedicine 7   2653-2660 2012年

研究論文（学術雑誌）, 共著, 査読有り

Comparison of two-dimensional periodic array of convex and concave nanostructures for efficient SERS templates

A. Zenidaka, Y. Tanaka, M. Miyanishi, M. Terakawa, M. Obara

Appl. Phys. A 103   225-231 2011年

研究論文（学術雑誌）, 共著, 査読有り

Randomely-grown high-dielectric-constant ZnO nanorods for near-field enhanced Raman scattering

M. Terakawa, Y. Tanaka, G. Obara, T. Sakano, M. Obara

Appl. Phys. A 102   661-665 2011年

研究論文（学術雑誌）, 共著, 査読有り

Dielectric microsphere mediated transfection using femtosecond laser

M. Terakawa, Y. Tanaka

Opt. Lett. 36   2877-2879 2011年

研究論文（学術雑誌）, 共著, 査読有り

Physics in plasmonic and Mie scattered near-field for efficient surface enhanced Raman scattering template

A. Zenidaka, T. Honda, M. Terakawa

Appl. Phys. A 105 2011年

研究論文（学術雑誌）, 共著, 査読有り

Direct observation of surface plasmon far field for regular surface ripple formation by femtosecond laser pulse irradi-ation of gold nanostructures onsilicon substrates

G. Obara, Y. Tanaka, N. N. Nedyalkov, M. Terakawa, M. Obara

Appl. Phys. Lett. 99   061106 2011年

研究論文（学術雑誌）, 共著, 査読有り

Plasmonic and Mie scattering control of far-field interference for regular ripple formation on various material substrates

G. Obara, N. Maeda, T. Miyanishi, M. Terakawa, N. N. Nedyalkov, M. Obara

Opt. Exp. 19   19093-19103 2011年

研究論文（学術雑誌）, 共著, 査読有り

Near-field interaction of two-dimensional high-permittivity spherical particle arrays on substrate in the Mie resonance scattering domain

Y. Tanaka, G. Obara, A. Zenidaka, N. N. Nedyalkon, M. Terakawa, M. Obara

Opt. Exp. 18 （ 26 ） 27226-27237 2010年12月

研究論文（学術雑誌）, 共著, 査読有り

Near-field interaction of two-dimensional high-permittivity spherical particle arrays on substrate in the Mie resonance scattering domain

Y. Tanaka, G. Obara, A. Zenidaka, N. N. Nedyalkon, M. Terakawa, M. Obara

Opt. Exp. 18 （ 26 ） 27226-27237 2010年

研究論文（学術雑誌）, 共著, 査読有り

Fabrication of void array in dielectric materials by femtosecond laser micro-processing for compact photonic devices

M. Terakawa, E. Toratani, T. Shirakawa, M. Obara

Appl. Phys. A 10   1041 2010年

研究論文（学術雑誌）, 共著, 査読有り

Size parameter effect of dielectric small particle mediated nano-hole patterning on silicon wafer by femtosecond laser

T. Sakai, Y. Tanaka, Y. Nishizawa, M. Terakawa, M. Obara

Appl. Phys. A 99   39-46 2010年

研究論文（学術雑誌）, 共著, 査読有り

Innovative cationic fullerenes as broad-spectrum light-activated antimicrobials

L. Huang, M. Terakawa, T. Zhiyentayev, Y. Huang, Y. Sawayama, A. Jahnke, G. Tegos, T. Wharton, M. Hamblin

Nanomedicine 6 （ 3 ） 442 2010年

研究論文（学術雑誌）, 共著, 査読有り

Uniform surface patterning with two-dimensional gold nanoparticle array excited by oblique femtosecond laser irradiation

T. Miyanishi, Y. Tanaka, M. Terakawa, M. Obara

Jpn. J. Appl. Phys 49 （ 5 ）  2010年

研究論文（学術雑誌）, 共著, 査読有り

Assessment of tissue alteration in skin after interaction with photomechanical waves used for gene transfection

M. Terakawa, H. Tsuda, H. Ashida, S. Sato

Lasers Surg. Med. 42   400 2010年

研究論文（学術雑誌）, 共著, 査読有り

Femtosecond laser near-field nano-ablation patterning using Mie resonance high dielectric constant particle with small size parameter

Yuto Tanaka, Go Obara, Akira Zenidaka, Mitsuhiro Terakawa and Minoru Obara

Appl. Phys. Lett. 96   261103 2010年

研究論文（学術雑誌）, 共著, 査読有り

Accelerated adhesion of grafted skin by laser-induced stress wave-based gene transfer of hepatocyte growth factor

K. Aizawa, S. Sato, M. Terakawa, D. Saitoh, H. Tsuda, H. Ashida, M. Obara

J. Biomed. Opt. 14 （ 6 ） 064043/1-9 2009年

研究論文（学術雑誌）, 共著, 査読有り

Enhanced transfection efficiency in laser-induced stress wave-assisted gene transfer at low laser fluence by increasing pressure impulse

S. Takano, S. Sato, M. Terakawa, H. Ashida, H. Okano, M. Obara

Appl. Phys. Exp. 1 （ 3 ） 038001/1-3 2008年

研究論文（学術雑誌）, 共著, 査読有り

Enhanced angiogenesis in graftedskins by laser-induced stress wave-assisted gene transfer of hepatocyte growth factor

M. Terakawa, S. Sato, D. Saitoh, H. Tsuda, H. Ashida, H. Okano, M. Obara

J. Biomed. Opt. 12   034031/1-8 2007年

研究論文（学術雑誌）, 共著, 査読有り

Laser-induced stress wave-assisted gene transfection with cationic liposome

M. Terakawa, R. Otsuka, S. Sato, Y. Satoh, K. Takishima, H. Ashida, H. Okano, M. Obara

Jpn. J. Appl. Phys. 46   L1243-L1245 2007年

研究論文（学術雑誌）, 共著, 査読有り

In vitro gene transfer to mammalian cells by the use of laser-induced stress waves: effects of stress wave parameters, ambient temperature, and cell type

M. Terakawa, S. Sato, H. Ashida, K. Aizawa, M. Uenoyama, Y. Masaki, M. Obara

J. Biomed. Opt. 11   014026/1-7 2006年

研究論文（学術雑誌）, 共著, 査読有り

Integrity of plasmid DNA after application of laser-induced stress waves used for gene transfection

M. Terakawa, S. Sato, H. Ashida, H. Okano, M. Obara

Jpn. J. Appl. Phys. 45   L768-769 2006年

研究論文（学術雑誌）, 共著, 査読有り

Targeted DNA transfection into the mouse central nerves system using a laser-induced stress wave

Y. Satoh, Y. Kanda, M. Terakawa, M. Obara, K. Mizuno, Y. Watanabe, S. Endo, S. Sato, K. Takishima

J. Biomed. Opt. 10   060501/1-3 2005年

研究論文（学術雑誌）, 共著, 査読有り

Gene transfer into mammalian cells by use of a nanosecond pulsed laser-induced stress wave

M. Terakawa, M. Ogura, S. Sato, H. Wakisaka, H. Ashida, M. Uenoyama, Y. Masaki, M. Obara

Opt. Lett., Vol. 29, pp. 1227-1229 29   1227-1229 2004年

研究論文（学術雑誌）, 共著, 査読有り

Enhanced photodynamic effect bythe assistance of nanosecond pulsed laser-induced stress wave

M. Terakawa, S. Sato, S. Kawauchi, H. Ashida, M. Obara

Jpn. J. Appl. Phys. 43   L877-L878 2004年

研究論文（学術雑誌）, 共著, 査読有り

Delivery of photosensitizer to cells by the stress wave induced by a single nanosecond laser pulse

M. Ogura, S.Sato, M. Terakawa, H. Wakisaka, M. Uenoyama, T. Ikeda, H. Ashida, M. Obara

Jpn. J. Appl. Phys. 42   L977-L979 2003年

研究論文（学術雑誌）, 共著, 査読有り