論文 - 高橋　英俊

Measurement of vacuum pressure with cantilever-based differential pressure sensor utilizing vapor pressure and narrow gap of cantilever

N Namioka, Y Takei, N Minh-Dung, T Usami, N Thanh-Vinh, H Takahashi, ...

2016 IEEE 29th International Conference on Micro Electro Mechanical Systems … （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2016-February   836 - 838 2016年

ISSN  9781509019731

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© 2016 IEEE. This paper reports a measurement method of vacuum pressure from 10-1 to 103 Pa with a piezoresistive cantilever-based differential pressure sensor (DPS). The gap around the cantilever of the DPS was narrow (2 μm) so that the air flow through it was suppressed. The through-hole beneath the sensor is connected to a chamber which is filled with saturated vapor. This method allows the pressure of the chamber to be stable at the vapor pressure of the liquid even when the exterior was vacuumed. The exterior vacuum pressure was calculated from the cantilever output since the vapor pressure of the chamber is known. We showed that the lower limit of measurable range was expanded into 0.1 Pa owing to noise reduction. The proposed method is promising to realize wide-range vacuum pressure measurement.

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Cantilever with 10-fold tunable spring constant using Lorentz force

W Ohnishi, H Takahashi, T Takahata, K Matsumoto, I Shimoyama

2016 IEEE 29th International Conference on Micro Electro Mechanical Systems … （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2016-February   866 - 868 2016年

ISSN  9781509019731

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© 2016 IEEE. This paper reports a cantilever with 10-fold tunable spring constant. The spring constant can be tuned both larger and smaller using Lorentz force generated by direct current which flows through the wiring on the cantilever. We designed the cantilever so that the maximum spring constant change by Lorentz force can be the same order as initial spring constant. The change of the spring constant was evaluated from the resonant frequency shift. The experimental result shows that the resonant frequency can be controlled from 1.1 kHz to 3.8 kHz, and the ratio of the tuned spring constant to the initial value was evaluated to be from 0.22 to 2.6.

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Depinning-induced capillary wave during the sliding of a droplet on a textured surface

TV Nguyen, T Tsukagoshi, H Takahashi, K Matsumoto, I Shimoyama

Langmuir 32 (37), 9523-9529 （Langmuir）  32 （ 37 ） 9523 - 9529 2016年

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  07437463

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© 2016 American Chemical Society. Surfaces covered with hydrophobic micro-/nanoscale textures can allow water droplets to slide easily because of low contact angle hysteresis. In contrast to the case of a droplet sliding on a smooth surface, when a droplet slides on a textured surface, it must recede from the textures at its rear edge and the resultant depinning events induce a capillary wave on the surface of the droplet. Although this depinning-induced capillary wave can be observed to some extent through high-speed imaging, important parameters of the wave, such as the wavelength and frequency, and the factors that determine these parameters are not fully understood. We report direct measurements of this depinning-induced capillary wave using microelectromechanical systems (MEMS)-based force sensors fabricated on a textured surface. Such sensor measurements reveal the frequency of the vibration occurring on the surface of the droplet, from which it is possible to calculate the wavelength of the capillary wave. We show that the frequency and wavelength of the depinning-induced capillary wave during the sliding of a water droplet on a micropillar array depend upon neither the size of the droplet nor its sliding velocity. However, the frequency (wavelength) decreases (increases) as the pitch of the micropillar array increases. We argue that the wavelength of the depinning-induced capillary wave is equal to the maximum length of the liquid bridges that develop at the micropillars before depinning. This hypothesis is confirmed by comparing the wavelengths obtained from the sensor measurements to the maximum liquid-bridge lengths calculated from observations using a high-speed camera.

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Chiral switchable THz metamaterial with MEMS reconfigurable spirals

T Kan, A Isozaki, N Kanda, N Nemoto, K Konishi, H Takahashi, ...

CLEO: QELS_Fundamental Science, FTh3D. 8 （2016 Conference on Lasers and Electro-Optics, CLEO 2016）  2016年

ISSN  9781943580118

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© 2016 OSA. We proposed a chiral switchable metamaterial using MEMS technology in the terahertz frequency region. Deformation of a flat metal spiral unit of the metamaterial creates three-dimensional spirals, and symmetrical chiral switching of the spiral could be performed by selecting the deformation directions; upper or lower. Ellipticity modulations amplitude as large as ±28° could be obtained in 1.08 THz, and optical responses were numerically analyzed.

Quantitative correlation between cardiac MIBG uptake and remaining axons in the cardiac sympathetic nerve in Lewy body disease

Takahashi M., Ikemura M., Oka T., Uchihara T., Wakabayashi K., Kakita A., Takahashi H., Yoshida M., Toru S., Kobayashi T., Orimo S.

Journal of Neurology, Neurosurgery and Psychiatry （Journal of Neurology, Neurosurgery and Psychiatry）  86 （ 9 ） 939 - 944 2015年09月

ISSN  00223050

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Objectives Reduced cardiac meta-iodobenzylguanidine (MIBG) uptake and loss of cardiac sympathetic axons, as its possible anatomical substrate, were both recognised in Lewy body disease (LBD), while their direct correlation has so far remained speculative. Increasing availability of autopsy-confirmed cases of LBD prompted us to quantify residual cardiac sympathetic axons to establish their relationship to cardiac MIBG uptake. Methods We collected cardiac tissue samples from 23 patients with autopsy-confirmed LBD and two non-LBD control patients who underwent 123 I-MIBG cardiac scintigraphy in life. Samples of the left ventricular anterior wall were stained with anti-tyrosine hydroxylase (TH) and anti-neurofilament (NF) antibodies as markers of cardiac nerve axons. We quantified the immunolabelled areas and assessed their correlation to standardised heart to mediastinum (H/M) ratios of 123 I-MIBG cardiac scintigraphy. Results Cardiac MIBG uptake in the early and delayed phases was reduced in 90.9% and 95.7% of patients with LBD, respectively. The area of TH-immunoreactive axons correlated significantly with the H/M ratio in the early (p=0.036) as well as in the delayed (p=0.018) phases. The area of NF-immunoreactive axons also correlated with the H/M ratio in the early (p=0.003) as well as in the delayed (p=0.001) phases. Conclusions Tight quantitative correlation between cardiac 123 I-MIBG uptake and corresponding loss of sympathetic axons in LBD, as established for the first time by this study, provides a scientific basis to confirm the reliability of MIBG cardiac scintigraphy as a powerful clinical tool to detect loss of these axons as a biomarker for the presence of Lewy body disease.

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MEMS可変スパイラルメタマテリアルのテラヘルツ応答

菅 哲朗, 磯崎 瑛宏, 神田 夏輝, 根本 夏紀, 小西 邦昭, 五神 真, 松本 潔, 下山 勲

応用物理学会学術講演会講演予稿集 （公益社団法人 応用物理学会）  2015.1   862 - 862 2015年02月

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Microneedle array fabrication using inclined/rotated uv lithography

Heo Y., Arakawa N., Yoshizawa S., Takahashi H., Kawano R.

MicroTAS 2015 - 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences （MicroTAS 2015 - 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences）     1442 - 1444 2015年

ISSN  9780979806483

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© 15CBMS-0001. We present a simple microneedle array fabrication technique using inclined/rotated UV lithography. The present method can create conic-shaped molding masters, thus reducing molding step to develop microneedles. By controlling inclined angle and UV energy density, dimensions of microneedles can be modified using a single mask. Therefore, we believe that the proposed method will simplify microneedle array fabrication.

A cantilever with comb structure modeled by a bristled wing of thrips for slight air leak

H Takahashi, A Isozaki, K Matsumoto, I Shimoyama

2015 28th IEEE International Conference on Micro Electro Mechanical Systems … （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2015-February （ February ） 706 - 709 2015年

ISSN  10846999

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© 2015 IEEE. This paper reports a cantilever with comb structure, inspired by a bristled wing of thrips which acts as a continuous membrane wing because of the effects of low Reynolds numbers. The comb structures are formed at the edges of the cantilever and its surrounding frame. When differential pressure is applied to the cantilever, both comb structures act as airflow suppression through the gap. The leakage of the fabricated comb cantilever was smaller than the normal cantilever due to the overlapping area of the combs, even the gap area was twice larger. The proposed structure will be utilized as a high sensitive barometric pressure change detector.

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6-Axis force/torque sensor for spike pins of sports shoes

H Ishido, H Takahashi, A Nakai, T Takahata, K Matsumoto, I Shimoyama

2015 28th IEEE International Conference on Micro Electro Mechanical Systems … （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2015-February （ February ） 257 - 260 2015年

ISSN  10846999

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© 2015 IEEE. This paper reports on a method to measure forces and torques acting on spike pins of sports shoes. We fabricated a 2 mm × 2 mm × 0.3 mm 6-axis force/torque sensor chip, which consists of 6 piezoresistive beams. From the resistance changes of the 6 beams, 6 components of forces and torques can be detected. The sensor chip was connected to a flexible printed circuit board (PCB) and covered with thin polydimethylsiloxane (PDMS). Then, the sensor chip and flexible PCB were embedded in spike-pin-shaped epoxy resin. We calibrated the spike-pin-shaped sensor, and confirmed that 6-axis forces and torques were able to be detected by the proposed sensor.

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3D structural foramation utilizing glass transition of a Parylene film

T Kan, A Isozaki, H Takahashi, K Matsumoto, I Shimoyama

2015 28th IEEE International Conference on Micro Electro Mechanical Systems … （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2015-February （ February ） 405 - 408 2015年

ISSN  10846999

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© 2015 IEEE. This paper reports on a fabrication method of three-dimensional micro structures supported by a Parylene thin film. The three-dimensional structure formation procedure starts with an out-of-plane actuation of the Si surface micromachined structure coated with a thin Parylene film. At the same time of the actuation, the environmental temperature was elevated above the glass transition temperature Tg of the Parylene, 80-100 °C, and then cooled down below Tg. In this process, the rearrangement of the Parylene film happens above Tg, and the consolidated Parylene after the cooling down maintains three-dimensional micro structures as actuated. In a proof-of-principle experiment, the three-dimensional spiral structures formed by 300-nm-thick silicon were fixed by 1-μm-thick Parylene film.

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Viscosity measurement based on the tapping-induced free vibration of sessile droplets using MEMS-based piezoresistive cantilevers

TV Nguyen, MD Nguyen, H Takahashi, K Matsumoto, I Shimoyama

Lab on a Chip 15 (18), 3670-3676 （Lab on a Chip）  15 （ 18 ） 3670 - 3676 2015年

共著, 査読有り,  ISSN  14730197

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© The Royal Society of Chemistry 2015. We report a simple technique to measure the free vibration of microlitre-sized droplets using an array of thirteen MEMS-based piezoresistive cantilevers and demonstrate its application for the measurement of viscosity. Because the damping of the free vibration of a liquid droplet is known to be affected by the viscosity of the liquid, measuring the vibration of a droplet allows the viscosity to be estimated from a dilute sample volume. However, conventional methods to measure the droplet vibration require sophisticated apparatuses, which hinder the development of a portable viscometer. Here, we show that MEMS-based piezoresistive cantilevers can be an excellent tool to measure the vibration of a sessile droplet due to the high sensitivity and simplicity of the readout scheme. Using the cantilever array, we analyse the normal force distribution on the contact area of a sessile droplet in the static state and during the vibration. Next, we show that the viscosity (from ∼1-30 mPa s) can be estimated within an error of less than 10% from the attenuation rate of the cantilever output during the tapping-induced vibration of small droplets (∼2.4 μL). In addition to the advantage of the small sample volume, the proposed viscometer has simple operation and readout schemes, which are desirable for many applications, including point-of-care testing and drug development.

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Two-axis MEMS-based force sensor for measuring the interaction forces during the sliding of a droplet on a micropillar array

N Thanh-Vinh, H Takahashi, K Matsumoto, I Shimoyama

Sensors and Actuators A: Physical 231, 35-43 （Sensors and Actuators, A: Physical）  231   35 - 43 2015年

共著, 査読有り,  ISSN  09244247

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© 2014 Elsevier B.V. Abstract In this paper, we proposed a 2-axis MEMS-based force sensor to directly measure the interaction forces during the sliding of a water droplet on a superhydrophobic surface with a micropillar array. In our sensor design, a 300-nm-thick silicon (Si) structure was fabricated beneath a single micrometer-sized pillar as the sensing element. Two piezoresistors were formed at the root of two opposite Si beams to detect the forces acting on the pillar surface in the normal and shear directions. The proposed sensor has a sensing resolution of less than 20 nN for both normal and shear forces. This resolution is confirmed to be sufficient to measure the forces of a droplet acting on a micropillar. The fabricated sensor was demonstrated to be able to measure the interaction forces during the sliding of a 7.5 μL water droplet on the micropillar array.

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Quad-axial piezoresistive force sensor probe by four sensing elements with sidewall doping method

H Takahashi, S Hirakawa, T Takahata, K Matsumoto, I Shimoyama

2015 Transducers-2015 18th International Conference on Solid-State Sensors … （2015 Transducers - 2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS 2015）     1089 - 1092 2015年

ISSN  9781479989553

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© 2015 IEEE. This paper reports a quad-axial force sensor probe which can measure tri-axial forces and one torque around the probe. By forming piezoresistors three dimensionally on the probe supporting beams, four sensing element can detect quad-axial force/torque on the probe tip. We demonstrated that the fabricated sensor had condition number of 2.6 with force resolutions under 1.0 μN and torque resolution under 1.0 nNm.

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Out-of-plane actuation with a sub-micron initial gap for reconfigurable terahertz micro-electro-mechanical systems metamaterials

A Isozaki, T Kan, H Takahashi, K Matsumoto, I Shimoyama

Optics express 23 (20), 26243-26251 （Optics Express）  23 （ 20 ） 26243 - 26251 2015年

共著, 査読有り,  ISSN  1094-4087

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© 2015 Optical Society of America. We propose a reconfigurable terahertz (THz) metamaterial that can control the transmittance by out-of-plane actuation with changing the sub-micron gap distance between electrically coupled metamaterial elements. By using the out-of-plane actuation, it was possible to avoid contact between the coupled metamaterial elements across the small initial gap during the adjustment of the gap size. THz spectroscopy was performed during actuation, and the transmission dip frequency was confirmed to be tunable from 0.82 to 0.92 THz for one linear polarization state and from 0.80 to 0.91 THz for the other linear polarization; the two polarizations were orthogonal. The proposed approach will contribute to the development of tunable metamaterials based on structural deformations.

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Enantiomeric switching of chiral metamaterial for terahertz polarization modulation employing vertically deformable MEMS spirals

T Kan, A Isozaki, N Kanda, N Nemoto, K Konishi, H Takahashi, ...

Nature communications 6, 8422 （Nature Communications）  6   8422 2015年

共著, 査読有り,  ISSN  2041-1723

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© 2015 Macmillan Publishers Limited. All rights reserved. Active modulation of the polarization states of terahertz light is indispensable for polarization-sensitive spectroscopy, having important applications such as non-contact Hall measurements, vibrational circular dichroism measurements and anisotropy imaging. In the terahertz region, the lack of a polarization modulator similar to a photoelastic modulator in the visible range hampers expansion of such spectroscopy. A terahertz chiral metamaterial has a huge optical activity unavailable in nature; nevertheless, its modulation is still challenging. Here we demonstrate a handedness-switchable chiral metamaterial for polarization modulation employing vertically deformable Micro Electro Mechanical Systems. Vertical deformation of a planar spiral by a pneumatic force creates a three-dimensional spiral. Enantiomeric switching is realized by selecting the deformation direction, where the polarity of the optical activity is altered while maintaining the spectral shape. A polarization rotation as high as 28° is experimentally observed, thus providing a practical and compact polarization modulator for the terahertz range.

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Characteristic evaluation of a bristled wing using mechanical models of a thrips wings with MEMS piezoresistive cantilevers

H TAKAHASHI, K SATO, MD NGUYEN, K MATSUMOTO, I SHIMOYAMA

Journal of Biomechanical Science and Engineering 10 (2), 14-00233-14-00233 （Journal of Biomechanical Science and Engineering）  10 （ 2 ） 1 - 10 2015年

共著, 査読有り,  ISSN  18809863

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© 2015 The Japan Society of Mechanical Engineers. This paper discusses similar-scale mechanical models of a thrips wing using microelectromechanical systems (MEMS) piezoresistive cantilevers to quantitatively evaluate bristled wing characteristics. Each cantilever had combs with varying widths and neighboring gaps that were adjusted so that a constant surface area was maintained. The cantilever body was 1,324 × 256 × 5 μm³ in size. An aerodynamic drag force from the airflow applied to the cantilever surface was measured using the fractional resistance change of the piezoresistor due to the cantilever's deformation. The aerodynamic characteristics of each model were evaluated in a wind tunnel with airflow velocities between 1.2 and 5.6 m/s. The experimental results suggest that at a lower comb-width-based Reynolds number that was approximately equal to that of a bristled wing of a thrips, the comb areas of the cantilever act as an airflow suppression due to boundary layer effects, which results in an increased aerodynamic force.

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Fusion of cantilever and diaphragm pressure sensors according to frequency characteristics

R Watanabe, N Minh-Dung, H Takahashi, T Takahata, K Matsumoto, ...

2015 28th IEEE International Conference on Micro Electro Mechanical Systems … （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2015-February （ February ） 212 - 214 2015年

ISSN  10846999

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© 2015 IEEE. This paper reports on an approach to measure sensitive barometric pressure by fusing a cantilever-based differential pressure sensor (DPS) and a commercially available diaphragm-based absolute pressure sensor (APS). At high frequency, the DPS can detect smaller pressure change than the APS. At low frequency, the APS shows less drift absolute pressure than the DPS. By utilizing the DPS and APS at each advantageous frequency, we propose a highly sensitive and drift-free measurement of barometric pressure.

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Insects have hairy eyes that reduce particle deposition

GJ Amador, F Durand, W Mao, S Pusulri, H Takahashi, VT Nguyen, ...

The European Physical Journal Special Topics 224 (17-18), 3361-3377 （European Physical Journal: Special Topics）  224 （ 17-18 ） 3361 - 3377 2015年

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  19516355

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© 2015, EDP Sciences and Springer. An insect’s eyes may make up to 40% of its body’s surface, and are in danger of being coated by foreign particles such as dust and pollen. To protect them, several insect species possess an array of ocular hairs evenly spaced between each photoreceptor unit. Although these hairs have been observed for over 50 years, their purpose remains a mystery. In this study, we elucidate the function of ocular hairs using a combination of experiments, numerical simulation and micro-fabrication. We measure the eyes of 18 species of insects and find that the length of their ocular hairs is equal to their spacing. We conduct wind tunnel experiments using both an insect eye mimic and an at-scale fabricated micro-pillar array of the same dimensions as the insect eye. Our experiments and simulations show that ocular hairs reduce airflow at the eye surface by up to 90%. We conclude that ocular hairs act similarly to mammalian eyelashes: as insects fly, ocular hairs deflect incoming air and create a zone of stagnant air. Airflow and particle deposition are reduced dramatically, while light is only minimally occluded. Micro-scale ocular hairs may find application in the deployment of sensors outdoors, for which accumulation of airborne dust and pollen has no current solution.

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Airflow shear stress sensor using side-wall doped piezoresistive plate

R Kazama, H Takahashi, T Takahata, K Matsumoto, I Shimoyama

2015 28th IEEE International Conference on Micro Electro Mechanical Systems … （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2015-February （ February ） 710 - 713 2015年

ISSN  10846999

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© 2015 IEEE. This paper reports on a shear stress sensor for airflow. The sensor consists of a plate, side-wall doped beams and surrounding membrane with narrow gaps. The sensor plate was 300 μm×350 μm×3 μm in size. The plate was supported by the side-wall doped beams, which can detect their horizontal deformation. The sensor structure was designed not to disturb target airflow circumstance owing to its flat surface. The fabricated sensor was able to measure shear stress of laminar airflow with the resolution under 1.0 Pa.

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Differential pressure sensor

I Shimoyama, K Matsumoto, T Takahata, KAN Tetsuo, K Kuwana, ...

US Patent 9,188,497 2015年