Papers - Takahashi, Hidetoshi

Spring constant measurement using a MEMS force and displacement sensor utilizing paralleled piezoresistive cantilevers

Sumihiro Kohyama, Hidetoshi Takahashi, Satoru Yoshida, Hiroaki Onoe, Kayoko Hirayama-Shoji, Takuya Tsukagoshi, Tomoyuki Takahata and Isao Shimoyama

Journal of Micromechanics and Microengineering (Institute of Physics Publishing)  28 ( 4 ) 045013 2018.02

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0960-1317

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This paper reports on a method to measure a spring constant on site using a micro electro mechanical systems (MEMS) force and displacement sensor. The proposed sensor consists of a force-sensing cantilever and a displacement-sensing cantilever. Each cantilever is composed of two beams with a piezoresistor on the sidewall for measuring the in-plane lateral directional force and displacement. The force resolution and displacement resolution of the fabricated sensor were less than 0.8 μN and 0.1 μm, respectively. We measured the spring constants of two types of hydrogel microparticles to demonstrate the effectiveness of the proposed sensor, with values of approximately 4.3 N m-1 and 15.1 N m-1 obtained. The results indicated that the proposed sensor is effective for on-site spring constant measurement.

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Analysis of THz Response of Frame Structures for Achieving Thin-film-type Metamaterials

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

IEEJ Transactions on Sensors and Micromachines 138, 281-286 (IEEJ Transactions on Sensors and Micromachines)  138 ( 7 ) 281 - 286 2018

ISSN  13418939

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© 2018 The Institute of Electrical Engineers of Japan. In this paper, we report on analytical results of terahertz (THz)-wave response of frame structures that support a thin film where metamaterial elements exist. Since the transmittance spectra of the metamaterial including the support frames differ from those of the metamaterial elements excluding the frames, investigation of influences of the frames on the measured spectra is important. A preliminary analysis revealed that the spectra of the metamaterial elements are partially recovered by compensating the measured spectra using time-domain transmittance waves of a bulk silicon-on-insulator wafer, from which the support frames are made. We experimentally demonstrate that the spectra of the support frames depend on the width, but not on the pitch, of the frames. Moreover, we show that a slab-type waveguide model can explain the interference between the support frames and the incident THz waves. The physical mechanism of THz response of support frames, which are clarified in this article, will be helpful to design thin-film type metamaterials.

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Waterproof pitot tube with high sensitive differential pressure sensor and nano-hole array

H Takahashi, I Shimoyama

2018 IEEE Micro Electro Mechanical Systems (MEMS), 214-217 (Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS))  2018-January   214 - 217 2018

ISSN  9781538647820

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© 2018 IEEE. This paper reports a Pitot tube type airflow sensor, which achieves both high sensitivity and water resistance. The proposed Pitot tube is composed of piezoresistive cantilevers as differential pressure sensing elements and nano-hole arrays as waterproof elements. The nano-hole arrays are attached to the air inlets, which are located the tip of the tube and sides of the sphere. When airflow is applied to the Pitot tube, air passes through the nano-hole arrays, and differential pressure between two inlets acts on the piezoresistive cantilevers. On the other hand, when locating in water, the nano-hole arrays protect the water penetration into the tube. The Pitot tube will be used for the airspeed measurement of flying marine birds.

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Miniaturization of a grating-based SPR type near-infrared spectrometer by using vibration of a MEMS cantilever

M Oshita, H Takahashi, T Kan

2018 IEEE Micro Electro Mechanical Systems (MEMS), 688-691 (Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS))  2018-January   688 - 691 2018

ISSN  9781538647820

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© 2018 IEEE. This paper reports on a miniaturization method of near-infrared spectrometer based on a plasmonic near-infrared photodetector. The spectrometer has an n-typed Si cantilever with an Au diffraction grating for Surface Plasmon Resonance (SPR) generation. Mechanical vibration of the cantilever provides alternation of the angle of incidence of the light to be measured. Coupled to SPR, the light energy is transduced to photocurrent. Since the different incident angle corresponds to different SPR resonant wavelength, the electrical measurement data of photocurrent during the cantilever vibration provides the whole spectrum information of the incident light. In this time, we developed a spectrometer device and measured time varying series of photocurrent during the cantilever vibration. Waveforms of the series were clearly dependent on the incident wavelength, and coherent to the SPR theory.

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Load dependency measurement of IPS cell-derived cardiomyocytes' contraction

K Matsudaira, H Takahashi, KH Shoji, TV Nguyen, T Tsukagoshi, ...

2018 IEEE Micro Electro Mechanical Systems (MEMS), 129-132 (Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS))  2018-January   129 - 132 2018

ISSN  9781538647820

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© 2018 IEEE. In this paper, we propose a method to evaluate relationships between twitch forces and static stretch stimuli of iPS cell-derived cardiomyocytes (iPSC-CMs) (force-length relation). The method realized the twitch force measurement of iPSC-CMs statically stretched under the culturing condition. As a result, twitch forces of a few tens of μΝ were measured, and the variation of twitch forces was observed as the static stretch was increased.

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High sensitive and large area force plate for ground reaction force measurement of ant running

S Kohyama, H Takahashi, T Takahata, I Shimoyama

2018 IEEE Micro Electro Mechanical Systems (MEMS), 874-877 (Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS))  2018-January   874 - 877 2018

ISSN  9781538647820

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© 2018 IEEE. This paper reports on a MEMS force plate for measurement of total ground reaction force (GRF) of an ant during running. To achieve both high force sensitivity and ensuring area for ant running with several steps, the MEMS force plate consisted of two cantilever chips and one plate which were fabricated separately. The force plate was designed to measure vertical directional force with the force resolution under 0.5 μΝ. Using the fabricated MEMS force plate, we measured the GRF of Messor aciculatus. The results showed that the fluctuation of the ground reaction force was 3.7 % to the body weight of the ant.

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Ground effect measurement of butterfly take-off

T Hagiwara, H Takahashi, T Takahata, I Shimoyama

2018 IEEE Micro Electro Mechanical Systems (MEMS), 832-835 (Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS))  2018-January   832 - 835 2018

ISSN  9781538647820

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© 2018 IEEE. This paper reports on a measurement of ground effect during a butterfly taking-off. We developed a differential pressure sensor array and a force plate to measure the pressure distribution on the ground and jumping force of legs, respectively. The force caused by the ground effect was evaluated as the integration of the pressure distribution. The aerodynamic force of wings was obtained from the jumping force and the acceleration of the taking-off motion. The acceleration was obtained from high-speed camera images. The result showed that the force on the ground was approximately 40% of the aerodynamic force.

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Cantilever pressure sensor with division portions for dividing lever resistance and having piezoresistor element

I Shimoyama, K Matsumoto, H Takahashi, MD Nguyen, T Uchiyama, ...

US Patent 9,995,642  2018

MEMS-based pressure sensor with a superoleophobic membrane for measuring droplet vibration

TV Nguyen, H Takahashi, I Shimoyama

2017 19th International Conference on Solid-State Sensors, Actuators and … (TRANSDUCERS 2017 - 19th International Conference on Solid-State Sensors, Actuators and Microsystems)     1152 - 1155 2017

ISSN  9781538627310

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© 2017 IEEE. We report on a sensor design to measure the vibration of small droplets. The sensor consists of a piezoresistive cantilever and a chamber covered with a superoleophobic membrane. The vibration of a droplet on the membrane causes the pressure of the chamber to change. Since the cantilever is able to detect a pressure change of less than 0.1 Pa, the vibration of the droplet can be precisely measured by the cantilever. In comparison to previously developed MEMS-based force sensor to measure the droplet vibration, the current sensor design offers several benefits including: wide range of usable liquids, simple sensing scheme (only one sensor is required) and capability to be disposable. With these advantages, our method is believed to be useful in measuring viscosity of small droplet for point-of-care application.

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A wall shear stress sensor using a pair of sidewall doped cantilevers

TV Nguyen, R Kazama, H Takahashi, T Takahata, K Matsumoto, ...

Journal of Micromechanics and Microengineering 27 (7), 075017 (IOP PUBLISHING LTD)  27 ( 7 ) 075017 2017

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09601317

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In this paper, we report on a micro-electro mechanical system (MEMS)-based piezoresistive sensor for measuring shear stress induced by an airflow. The advantages of the proposed sensor include a simple sensing method and a high resonance frequency due to the small size of the sensing elements. Our sensor consists of a pair of 3 mu m thick cantilevers with piezoresistors formed on the sidewall of their hinges to detect lateral deformation in the cantilevers induced by an airflow. Each cantilever has a 200 mu m x 400 mu m plate supported by two 150 mu m long, 4 mu m wide beams. The piezoresistors on the two cantilevers are designed to deform in opposite manners when a shear stress is applied and in the same manner when a pressure is applied. Therefore, the applied shear stress can be detected from the difference in the responses of the two cantilevers without becoming conflated with pressure. In this paper, the design, fabrication and evaluation of the proposed sensor are reported and compared to numerical simulation results. From the experimental results, the resolution of the sensor and its first resonance frequency are 1.3 Pa and 3.9 kHz, respectively. Moreover, we show that the effect of temperature on the readout of the sensor can be eliminated using a temperature-compensating piezoresistor fabricated on the same sensor chip. Finally, using the fabricated sensor, the measurement of the shear stress induced by an airflow with velocity between -10 and 10 m s(-1) is demonstrated.

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Uniform areal-distribution of UV intensity by synchronizing signal-waveforms and position of a UV-LED array

H Takahashi, I Shimoyama, YJ Heo

Applied Physics Letters 111 (26), 263503 (AMER INST PHYSICS)  111 ( 26 ) 263503 2017

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00036951

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This paper describes a theoretical approach to give an irradiated area a uniform distribution of LED light intensity by synchronizing the signal waveforms and position control of the LEDs. Although UV-LEDs have attracted considerable attention as alternative light sources for ultraviolet (UV) lithography in Micro Electro Mechanical Systems (MEMS) fabrication, mainly because of their low cost and low power consumption, the realization of a uniform UV intensity over an area remains challenging. Here, we propose a method to achieve a uniform areal intensity within an irradiated area by synchronizing the signal waveform and position of a UV-LED array. To verify our theoretical calculation, we developed a system with a UV-LED array whose position is controlled by a linear actuator. The intensity of the UV-LED array is controlled by a pulse width modulation (PWM) signal, which is synchronized with the position of the linear actuator. Using this system, we fabricated 2D micropatterns and 3D microstructures with high uniformity in the irradiated area. The proposed method is expected to facilitate practical LED-based lithography in MEMS fabrication. Published by AIP Publishing.

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Scalable fabrication of PEGDA microneedles using UV exposure via a rotating prism

H Takahashi, YJ Heo, I Shimoyama

Journal of Microelectromechanical Systems 26 (5), 990-992 (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC)  26 ( 5 ) 990 - 992 2017

Research paper (scientific journal), Joint Work, Accepted,  ISSN  10577157

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We propose a simple, fast, height-scalable, and direct way to fabricate highly biocompatible polyethylene glycol diacrylate (PEGDA) microneedles. A needle-shaped distribution of ultraviolet (UV) exposure dose is formed in PEGDA by applying UV light through a rotating prism. A prism makes UV light rays bend, such that the base angle of the prism determines the inclined angle of the light. Thus, the microneedle height can be controlled by varying the base angles of the prism. We experimentally demonstrate the direct height-scalable potential. The microneedle height decreases and the microneedle tip angle increases with increases in the base angle of the prism. These results indicate that the microneedle geometry can be easily controlled by the base angle of a prism without additional microfabrication. In addition, unlike photoresist microneedles, PEGDA does not require any thermal baking, thus enabling well-defined symmetric needle formation with short process time. Therefore, the present method can facilitate PEGDA microneedles to practical applications. [2017-0136]

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Pressure sensor having cantilever and displacement measurement unit

I Shimoyama, K Matsumoto, H Takahashi, MD Nguyen, Y Shinohara, ...

US Patent 9,551,621  2017

Pressure sensor

I Shimoyama, K Matsumoto, H Takahashi, MD Nguyen, T Uchiyama, ...

US Patent App. 15/512,701  2017

Pressure sensor

I Shimoyama, K Matsumoto, H Takahashi, MD Nguyen, T Uchiyama, ...

US Patent App. 15/116,967  2017

Evaluation of ground slippery condition during walk of bipedal robot using MEMS slip sensor

T Okatani, H Takahashi, T Takahata, I Shimoyama

2017 IEEE 30th International Conference on Micro Electro Mechanical Systems … (Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS))     1033 - 1035 2017

ISSN  9781509050789

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© 2017 IEEE. This paper reports on a method to evaluate ground slippery condition using a MEMS slip sensor. The sensor discriminates between ground slippery and non-slippery conditions during walking motions of a bipedal robot, which enables the robot to prevent a slip. First, we evaluated the responses of the sensor pressed against an oiled or non-oiled surface. Then, we proposed a discriminating method between the oiled and non-oiled surfaces using the sensor. Finally, we demonstrated that a bipedal robot was able to evaluate the slippery condition of the ground where the foot of the robot landed during walk.

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Force Measurement by MEMS Sensors during Ant Running

H TAKAHASHI, I SHIMOYAMA

Journal of the Visualization Society of Japan 37 (144), 20-23 (可視化情報学会)  37 ( 144 ) 20 - 23,図巻頭1p 2017

ISSN  0916-4731

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Biomimetics and Visualization

H TANAKA, H TAKAHASHI

Journal of the Visualization Society of Japan 37 (144), 2-2 (The Visualization Society of Japan)  37 ( 144 ) 2 - 2 2017

ISSN  0916-4731

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Gas sensor

I Shimoyama, K Matsumoto, KAN Tetsuo, Y Takei, H Takahashi, K Ishizu, ...

US Patent 9,546,948  2017

How merging droplets jump off a superhydrophobic surface: Measurements and model

T Mouterde, TV Nguyen, H Takahashi, C Clanet, I Shimoyama, D Quéré

Physical Review Fluids 2 (11), 112001 (AMER PHYSICAL SOC)  2 ( 11 ) 112001(R) 2017

Research paper (scientific journal), Joint Work, Accepted,  ISSN  2469-990X

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We investigate how drops merging on a nonwettable surface jump off this surface, for both symmetric and asymmetric coalescences. For this purpose, we design and build a microelectro mechanical system sensor able to quantify forces down to the micro-Newton scale at a high acquisition rate (200 kHz). Using this device, we perform direct force measurements of self-propelled droplets coupled to high-speed imaging. Experimental data show that the total momentum of the drop after coalescence mainly depends on the size of the smaller drop. Exploiting this finding, we quantitatively predict the takeoff speed of jumping drop pairs and show how to correct the usual argument based on energy conservation.

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