研究者詳細 - 安藤　景太

論文 - 安藤　景太

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Quantitative Analysis of Acoustic Pressure for Sonophoresis and Its Effect on Transdermal Penetration

Kurashina Y., Asano R., Matsui M., Nomoto T., Ando K., Nakamura K., Nishiyama N., Kitamoto Y.

Ultrasound in Medicine and Biology （Ultrasound in Medicine and Biology） 48 （ 5 ） 933 - 944 2022年05月

共著, 査読有り, ISSN 03015629

Ultrasound facilitates the penetration of macromolecular compounds through the skin and offers a promising non-invasive technique for transdermal delivery. However, technical difficulties in quantifying ultrasound-related parameters have restricted further analysis of the sonophoresis mechanism. In this study, we devise a bolt-clamped Langevin transducer-based sonophoresis device that enables us to measure with a thin lead zirconate titanate (PZT) sensor. One-dimensional acoustic theory accounting for wave interaction at the skin interface indicates that the acoustic pressure and cavitation onset on the skin during sonophoresis are sensitive to the subcutaneous support, meaning that there is a strong need to perform the pressure measurement in an experimental environment replacing the human body. From a series of the experiments with our new device, the transdermal penetration of polystyrene, silica and gold nanoparticles is found to depend on the size and material of the particles, as well as the hardness of the subcutaneous support material. We speculate from the acoustic pressure measurement that the particles' penetration results from the mechanical action of cavitation.

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Chemically controlled megasonic cleaning of patterned structures using solutions with dissolved gas and surfactant

B.N. Sahoo, S.Y. Han, N.P. Yerriboina, H. Kim, K. Ando, T.G. Kim, B. Kang, A. Klipp, J.G. Park

Ultrasonics Sonochemistry （Elsevier） 82 105859 2022年01月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 13504177

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Ultrasound-induced nonlinear oscillations of a spherical bubble in a gelatin gel

K. Murakami, Y. Yamakawa, J.Y. Zhao, E. Johnsen, K. Ando

Journal of Fluid Mechanics （Cambridge University Press） 924 A38 2021年08月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00221120

We experimentally observe and theoretically analyse oscillations of a spherical bubble in a gelatin gel under ultrasound irradiation to quantify viscoelastic effects on the nonlinear bubble dynamics. A bubble nucleus is generated by focusing a laser pulse into a 6 wt% gelatin gel supersaturated with dissolved air, which enables us to control the bubble radius at mechanical equilibrium via influx of the gas air into the bubble. Linearized and finite-amplitude oscillations of the bubble are driven by 28 kHz ultrasound and recorded by a high-speed camera; the resonance curves of the oscillation amplitude as a function of the equilibrium radius are constructed for different ultrasound intensities. First, the viscosity and shear modulus of the gel are obtained by fitting the resonance curve (for the lowest ultrasound intensity) to the linearized solution of the Rayleigh-Plesset model that accounts for the gel's nonlinear elasticity of neo-Hookean type and diffusive effects on the bubble dynamics. Next, finite-amplitude oscillations of the bubble are compared with the nonlinear Rayleigh-Plesset calculations. The comparison suggests a need to include the gel's elasticity in the calculations to more accurately reproduce the nonlinear bubble dynamics. Another important finding is that the so-called spring softening feature appears in the experimentally determined resonance curve as the oscillation amplitude increases, which can be predicted by the Rayleigh-Plesset model. Furthermore, our experiment with the highest ultrasound intensity shows non-spherical oscillation of mode 1 that does not appear in the case of water but can be predicted by shape instability theory.

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Acoustic streaming induced by MHz-frequency ultrasound extends the volume limit of cell suspension culture

Oyama T., Imashiro C., Kuriyama T., Usui H., Ando K., Azuma T., Morikawa A., Kodeki K., Takahara O., Takemura K.

Journal of the Acoustical Society of America （Journal of the Acoustical Society of America） 149 （ 6 ） 4180 - 4189 2021年06月

ISSN 00014966

Large-scale cell suspension culture technology opens up opportunities for numerous medical and bioengineering applications. For these purposes, scale-up of the culture system is paramount. For initial small-scale culture, a simple static suspension culture (SSC) is generally employed. However, cell sedimentation due to the lack of agitation limits the culture volume feasible for SSC. Thus, when scaling up, cell suspensions must be manually transferred from the culture flask to another vessel suitable for agitation, which increases the risk of contamination and human error. Ideally, the number of culture transfer steps should be kept to a minimum. The present study describes the fabrication of an ultrasonic suspension culture system that stirs cell suspensions with the use of acoustic streaming generated by ultrasound irradiation at a MHz frequency. This system was applied to 100-mL suspension cultures of Chinese hamster ovary cells—a volume ten-fold larger than that generally used. The cell proliferation rate in this system was 1.88/day when applying an input voltage of 40 V to the ultrasonic transducer, while that of the SSC was 1.14/day. Hence, the proposed method can extend the volume limit of static cell suspension cultures, thereby reducing the number of cell culture transfer steps.

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Ultrasound-triggered on-demand drug delivery using hydrogel microbeads with release enhancer

Kubota T., Kurashina Y., Zhao J.Y., Ando K., Onoe H.

Materials and Design （Materials and Design） 203 2021年05月

ISSN 02641275

Ultrasound-triggered drug delivery has been widely researched for its potential to improve the therapeutic efficacy of drugs. This paper presents drug release using hydrogel microbeads with release enhancer for efficient ultrasound-triggered drug delivery. By using a centrifuge-based microfluidic device, drug-model-encapsulating calcium alginate hydrogel microbeads containing tungsten particles with high acoustic impedance were fabricated. Because the tungsten particles work as release enhancer, the hydrogel microbeads become to have high sensitivity to ultrasound with localized variation in acoustic impedance so that the release rate of drug models improves. By applying ultrasound at 20 kHz to the hydrogel microbeads, the release of fluorescent silica nanoparticles that are a drug model for virus vectors, micelles, and proteins was tested. Importantly, the proposed hydrogel microbeads released the drug model even under a cavitation-suppressed environment. Furthermore, the additional coating on the hydrogel microbeads with poly-L-lysine enabled us to adjust the release rate of the drug model. The proposed ultrasound-triggered drug release system using release enhancer is expected to be an effective approach for expanding the varieties of applicable treatments using on-demand drug delivery systems.

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Particle removal in ultrasonic water flow cleaning: Role of cavitation bubbles as cleaning agents

Ando K., Sugawara M., Sakota R., Ishibashi T., Matsuo H., Watanabe K.

Solid State Phenomena （Trans Tech Publications Inc. ） 314 218 - 221 2021年02月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 1662-9779

周波数0.43 MHzの超音波水流を用いた洗浄試験を行った。直径30 mmのガラス円板に直径0.5 μmのシリカ粒子をスピンコートしたものを洗浄サンプルとして超音波水流洗浄試験を行い、洗浄の様子の可視化、ヘイズ法に基づく洗浄後のサンプルの粒子除去の評価を行った。洗浄の可視化から、洗浄面上に水流衝突箇所を中心に同心円状にトラップされたキャビテーション気泡が等間隔に現れることが確認された。これに起因し、洗浄試験後のサンプル表面には洗浄ムラが生じてしまうことが示された。

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Interaction between free-surface oscillation and bubble translation in a megasonic cleaning bath

Katano Y., Ando K.

Solid State Phenomena （Trans Tech Publications Inc.） 314 202 - 206 2021年02月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 1662-9779

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Simulation of rayleigh bubble growth near a no-slip rigid wall

Tanaka T., Ando K.

Solid State Phenomena （Trans Tech Publications Inc.） 314 192 - 196 2021年02月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 1662-9779

すべりなしの剛体壁面近傍に存在する気泡のレイリー成長に関するシミュレーションを行った。膨張気泡からの音響波放射、壁面に作用するせん断応力を評価するために、支配方程式として圧縮性流れに対するナビエ・ストークスの式を採用した。気泡の急膨張に伴う衝撃波が壁面上を伝播することで、壁面上に強いせん断応力が生成されることが示された。これは、超音波洗浄において、壁面近傍の音響キャビテーション気泡の膨張が洗浄に寄与することを示唆する結果と言える。

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Visualization of acoustic waves and cavitation in ultrasonic water flow

Usui H., Ishibashi T., Matsuo H., Watanabe K., Ando K.

Solid State Phenomena （Trans Tech Publications Inc.） 314 186 - 191 2021年02月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 1662-9779

超音波（0.43 MHz、0.95 MHz）水流洗浄におけるキャビテーション現象を可視化するための実験を行った。シュリーレン法に基づく超音波水流中の音響場の可視化から、入射超音波と洗浄面からの反射超音波の重ね合わせで生じる音響定在波の形成を確認した。バックライト法に基づく流動場の可視化から、超音波水流中にキャビテーション気泡が現れ、音響定在波中を捕捉される気泡および水流とともに移流する気泡の存在を確認した。さらに、洗浄面を広がる液膜流れにおいて、超音波照射により体積振動するキャビテーション気泡が並進運動する様子が可視化された。

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Quasistatic growth of bubbles in a gelatin gel under dissolved-gas supersaturation

Ando K., Shirota E.

Physics of Fluids （Physics of Fluids） 31 （ 11 ） 111701 2019年11月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 10706631

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Low-intensity ultrasound induced cavitation and streaming in oxygen-supersaturated water: Role of cavitation bubbles as physical cleaning agents

Yamashita T., Ando K.

Ultrasonics Sonochemistry （Elsevier） 52 268 - 279 2019年04月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 13504177

ガス過飽和水を洗浄液として用いた低音圧の28kHz超音波による洗浄試験を行い、振動気泡の有する流体力学的作用が物理洗浄において重要な役割を果たすことを実証した。超音波洗浄槽の内部流動に関するPIV解析から、超音波キャビテーション気泡は、音響放射力の作用のもと液相中をすべり循環することを確認した。洗浄面付着気泡のミクロ観察から、振動気泡の近傍の液相流動促進により洗浄効果が得られることを示した。さらに、微細粒子を塗布したガラス面の洗浄後の粒子除去率に基づき洗浄効率を定義した上で、洗浄効率を最大化するガス過飽和度の最適値が存在することを示した。

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Growth control of leaf lettuce with exposure to underwater ultrasound and dissolved oxygen supersaturation

Kurashina Y., Yamashita T., Kurabayashi S., Takemura K., Ando K.

Ultrasonics Sonochemistry （Ultrasonics Sonochemistry） 51 292 - 297 2019年03月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 13504177

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Simulation of high-speed droplet impact against a dry/wet rigid wall for understanding the mechanism of liquid jet cleaning

Kondo T., Ando K.

Physics of Fluids （Physics of Fluids） 31 （ 1 ） 013303 2019年01月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 10706631

液膜で覆われた剛体壁への液滴の高速衝突に伴う水撃現象および壁面せん流の形成を、圧縮性ナビエ・ストークスの式に基づきシミュレーションを行った。液膜厚さをパラメータとする計算より、水撃圧力および壁面せん断応力の最大値に対する液膜の減衰効果を定量評価した。液滴衝突誘起の壁面せん断応力が、壁面に付着する微細粒子の除去に寄与することを、one-wayカップリング法に基づき指摘した。

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Comparison in high-speed droplet impact between single and multiple collisions against a wall covered with a liquid film

Fukuchi Y., Kondo T., Ando K.

ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019 （ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019） 5 2019年

ISSN 9780791859087

In semiconductor industry, liquid jet cleaning plays an important role because of its high cleaning efficiency and low environmental load. However, its cleaning mechanism is not revealed in detail because the experimental observation of high-speed and sub-micron droplets is challenging. Furthermore, higher impact velocity may give rise to surface erosion due to water-hammer shock loading from the impingement. To study cleaning mechanisms and surface erosion, numerical simulation of droplet impingement accounting for both viscosity and compressibility is an effective approach. In the previous study, wall-shear-flow generation has evaluated from the simulation of high-speed single droplet impingement. To evaluate more practical model of jet cleaning application, simulation of two droplets simplifying mono-dispersed splay of droplet train is favorable. Here, we numerically simulated impingement of two droplets, which allows for evaluating water-hammer pressure and wall shear stress. We consider the case of two water droplets (200 µ m in diameter) that collides continuously, at speed 50 m/s, at the inter-droplet distance from 250 to 400 µ m, with a no-slip rigid wall covered with a water layer (100 µ m in thickness). The simulation is based on compressible Navier-Stokes equations for axisymmetric flow and the mixture of two components appears in numerically diffusion interface expressed by the volume average and advection equation. The simulation is solved by finite-volume WENO scheme that can capture both shock waves and material interface. In our simulation, the impingement of second droplet impingement gain higher shear stress than the single droplet impingement. At the case that the inter-droplet distance is 300 µ m, maximum shear stress is 30.22 kPa (at the second droplet impingement), which is much larger than at the first droplet impingement (8.42 kPa). This result indicates how the second droplet impingement make wall shear flow induced by first droplet impingement stronger. From the parameter study of the inter-droplet distance, we can say that wall shear stress gets stronger as water layer thickness decreases. Furthermore, the maximum wall pressure is 1.96 MPa at the second droplet impingement, which is larger than at the first droplet impingement (1.46 MPa). From this study, the evaluation of surface erosion caused by jet cleaning is expected. The simulation suggests that multiple droplets impingement continuously may gain higher cleaning efficiency, which will give us a fundamental insight into liquid jet cleaning technologies. For further study, simulation of water column impingement and comparing the result of impingement of two droplets are expected.

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Visualization of bubble dissolution as a means to measure dissolved nitrogen concentration

Sato T., Yamashita T., Ando K.

ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019 （ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019） 5 2019年

ISSN 9780791859087

In ultrasonic cleaning, violent cavitation bubble dynamics causes material damage to cleaning surfaces, which is called cavitation erosion. The control of the dissolved gas concentration in cleaning liquid is effective to avoid cavitation erosion. The dissolved oxygen (DO) concentration is easily measured by a commercial DO meter, but the dissolved nitrogen (DN) concentration in water where multiple gas species are dissolved cannot be accurately measured with a commercially available DN meter. Therefore, it is important to construct a new method of measurement of DN concentration. In this study, we visualize the diffusion driven dissolution of bubble in air-saturated water and degassed water. The Epstein-Plesset theory considering multiple gas species is derived and compared with the experimental result where the DN concentration is treated as a fitting parameter in order to estimate the unknown DN concentration. Results indicates that the DN concentration can be measured by comparison between the theory and the relatively slow dissolution of bubble.

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Experimental study of free-surface deformation and cavitation bubble dynamics in a megasonic cleaning bath

Katano Y., Ando K.

ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019 （ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019） 5 2019年

ISSN 9780791859087

Underwater ultrasound causes various physical phenomena in megasonic cleaning baths, e.g. cavitation inception, bubble translation and free-surface deformation (FSD) due to acoustic radiation pressure. Because FSD is especially noticeable in the case of high frequency ultrasound due to its high directivity, it is essential to investigate the interaction between FSD and bubble translation in megasonic cleaning bath. In our present experiments, we construct a typical setup for megasonic cleaning and irradiate water with 1 MHz ultrasound vertically upwards. We visualize FSD and bubbles and analyze the height of FSD and the translational velocity in frequency space. The bubbles translate in both short and long time scales caused by bubble-bubble interaction and periodic FSD, respectively, and the latter has periodicity. The most dominant frequency component in FSD shows good agreement with that in the translational velocity of the bubbles and does not depend on whether cavitation occurs or not. Therefore, it is suggested that FSD causes periodicity of bubble translation.

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Effects of liquid viscosity on laser-induced shock dynamics

Kurahara H., Ando K.

ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019 （ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019） 5 2019年

ISSN 9780791859087

We experimentally study the effects of viscosity on laser-induced shockwave in glycerol-water solution. A shockwave is generated through rapid expansion of plasma, which is induced by focusing a 6 ns pulse laser (532 nm) of energy fixed at 1.66 ± 0.22 mJ into 80, 90, 100 wt% glycerol-water solution. The shockwave propagation is recorded by an ultra-high-speed camera taken at 100 Mfps together with a pulse laser stroboscope. The photographs are used to determine the shock front position as a function of time, which allows for calculating the shock pressure according to the stiffened-gas type Rankine–Hugoniot relation. It turns out that the initial plasma pressure is reduced by having higher glycerol concentration (i.e., higher viscosity); therefore, wave steepening effect is deemphasized, resulting in a smaller decay rate.

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Cavitation bubble nucleation induced by shock-bubble interaction in a gelatin gel

Oguri R., Ando K.

Physics of Fluids （Physics of Fluids） 30 （ 5 ） 051904 2018年05月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 10706631

ゼラチンゲルのキャビテーション初生圧力を見積もるための実験・シミュレーション連成による計測法を構築した。レーザー誘起衝撃波とガス気泡の干渉により生成される負圧を利用し、質量濃度10%のゲル中にキャビテーション初生を発生させた。実験より取得したレーザー誘起衝撃波の時間発展に基づき、圧力場を圧縮性オイラー計算から構築し、キャビテーション初生圧力を算定した。ゼラチンの質量濃度が10%の場合、キャビテーション初生に対する粘弾性の影響は限定的であることを示した。

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Aeration of water with oxygen microbubbles and its purging effect

T. Yamashita, K. Ando

Journal of Fluid Mechanics （Cambridge University Press） 825 16 - 28 2017年08月

研究論文（学術雑誌）, 共著, 査読有り

曝気水中で発泡したガス気泡の成長を実験的に観察し、その成長速度を理論と比較することにより、溶存窒素（DN）濃度を算定する手法を提案した。酸素マイクロバブル曝気により酸素過飽和水を生成し、酸素溶存（DO）濃度をDO計により測定した。生成した酸素過飽和水に挿入したガラス壁面上で発泡した球形ガス気泡は、Fickの拡散則に基づく溶存ガスの気泡への流入により成長を遂げる。物質拡散による準静的成長を記述するEpstein-Plessetの式を酸素・窒素の2成分系に適用し、実験より取得した気泡の成長速度と比較することによりDN濃度を算定した。

Experiment and modeling of translational dynamics of an oscillating bubble cluster in a stationary sound field

N. Sugita, K. Ando, T. Sugiura

Ultrasonics （Elsevier） 77 160 - 167 2017年02月

研究論文（学術雑誌）, 共著, 査読有り

定在音場下の気泡クラスターの挙動を可視化する実験を行い、観察されたクラスターの並進運動をビャクネス理論の拡張に基づきモデル化した。体積振動する気泡クラスターには、壁面との干渉すなわち同位相で振動する鏡像クラスターとの干渉により発現する第2 ビャクネス力が作用し、壁面に向かい並進運動することが観察された。この並進運動は、クラスター自身の慣性力、クラスター周囲の液相慣性力、および第2 ビャクネス力の釣り合いにより決定されることが示された。

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安藤 景太

論文 - 安藤 景太

安藤　景太

論文 - 安藤　景太