論文 - 高橋　英俊

Pillar-Type Laser-Induced Graphene Airflow Sensor Assembled Via Kirigami/Origami Technique

K Ohara, R Nakashima, H Takahashi

2024 IEEE 37th International Conference on Micro Electro Mechanical Systems …    813 - 816 2024年

ISSN  10846999

　概要を見る

This paper reports a pillar-type laser-induced graphene (LIG) airflow sensor assembled via Kirigami / Origami technique. The proposed sensing element can be fabricated by processing polyimide (PI) film with two types of lasers. In addition, the pillar assembled with the jigs maintains a three-dimensional structure. The prototype multiaxial airflow sensor fabricated by the proposed process responded quadratically to the wind speed and sinusoidally to the wind direction.

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Nest Box for Monitoring the Mass and Heart Rate Changes of a Growing Seabird Chick

Uematsu D., Kishimoto T., Harada K., Watanabe S., Sato K., Takahashi H.

IEEJ Transactions on Sensors and Micromachines 144 （ 1 ） 12 - 16 2024年

ISSN  13418939

　概要を見る

This study reports the development of a nest box that can be used to simultaneously measure changes in the mass and heart rate of a growing seabird chick. The nest box is equipped with two scales and a heart rate monitor. The zero-point drift is expected to be suppressed using two scales. The scale utilizes a noncontact displacement sensor with waterproofing and dustproofing. A silicone tube with one end closed and the other end connected to a pressure sensor is used as a heart monitor. The developed nest box allows noninvasive, sequential measurement of the mass and heart rate of a chick over several months.

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Nest Box for Monitoring the Mass and Heart Rate Changes of a Growing Seabird Chick

D Uematsu, T Kishimoto, K Harada, S Watanabe, K Sato, H Takahashi

ieej transactions on sensors and micromachines 144 (1), 12-16 2024年

Enhancing force plate design through optimization of spring constant distribution

Y Kawasaki, A Ogawa, H Takahashi

Sensors and Actuators A: Physical 374, 115468 374 2024年

ISSN  09244247

　概要を見る

Force plates have been widely used in various scientific fields to measure ground reaction forces experienced by animals and humans. A force plate that incorporates mechanical springs and non-contact displacement sensors offers the advantages of facilely modifying its shape and performance. However, the design protocol was limited to adjusting the plate size and spring constants of the springs supporting the plate at the four corners. Herein, we propose an optimization method for determining the spring constant distribution of a force plate. The proposed design enables the use of simulations to optimize the mechanical properties of the force plate, such as resonant frequency and error due to position. The experimental results demonstrated that the resonant frequency of the fabricated force plate was 133 Hz and the error due to position was within ±5 %. These results confirm that the proposed force plate can be effectively adjusted through optimization.

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Needle-type pressure sensor with silicone oil and parylene membrane inside for minimally invasive measurement

Kishimoto T., Agetsuma M., Hoshino A., Takahashi H.

Electronics and Communications in Japan 106 （ 3 ）  2023年09月

ISSN  19429533

　概要を見る

This paper addresses a pressure sensor for body pressure measurement. Many pressure sensors have been developed for disease treatment in the medical field. However, these sensors require inserting electronic components and other sensor elements via surgical operations, so the measurement physically burdens patients. Hence, we proposed a needle-type pressure sensor using MEMS (Micro Electro Mechanical Systems) cantilever. The sensor has a needle part with a thin membrane on the tip and is filled with incompressible fluid inside. The fractional resistance of the built-in piezoresistive cantilever varies according to the pressure change applied to the needle tip. We can measure body fluid pressure with minimal surgery by inserting a simple needle into the target organ. Because the fabricated sensor responded to pseudo-body pressure changes, it was suggested that the fabricated needle-type pressure sensor could detect pressure inside the body.

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Temperature Dependence of the Beating Frequency of hiPSC-CMs Using a MEMS Force Sensor

Ikegami Ryota, Tsukagoshi Takuya, Matsudaira Kenei, Shoji Kayoko Hirayama, Takahashi Hidetoshi, Nguyen Thanh-Vinh, Tamamoto Takumi, Noda Kentaro, Koyanagi Ken'ichi, Oshima Toru, Shimoyama Isao

SENSORS （Sensors）  23 （ 7 ）  2023年04月

ISSN  14248220

　概要を見る

It is expected that human iPS cell-derived cardiomyocytes (hiPSC-CMs) can be used to treat serious heart diseases. However, the properties and functions of human adult cardiomyocytes and hiPSC-CMs, including cell maturation, differ. In this study, we focused on the temperature dependence of hiPSC-CMs by integrating the temperature regulation system into our sensor platform, which can directly and quantitatively measure their mechanical motion. We measured the beating frequency of hiPSC-CMs at different environmental temperatures and found that the beating frequency increased as the temperature increased. Although the rate at which the beating frequency increased with temperature varied, the temperature at which the beating stopped was relatively stable at approximately 20 °C. The stopping of beating at this temperature was stable, even in immature hiPSC-CMs, and was considered to be a primitive property of cardiomyocytes.

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Open planar acoustic notch filter using a film-integrated Helmholtz resonator array

Mizukoshi Fumiya, Takahashi Hidetoshi

JAPANESE JOURNAL OF APPLIED PHYSICS （Japanese Journal of Applied Physics）  62 （ 3 ）  2023年03月

ISSN  0021-4922

　概要を見る

Acoustic filters are used to transmit or attenuate noise in a specific frequency band. However, previous acoustic filters consisting of rigid structures generally required a large housing of a size equivalent to the wavelength, limiting their downsizing. This study presents an open planar acoustic notch filter using a film-integrated Helmholtz resonator (HR) array. A film divides the HR chamber and resonates with the HR. The film-integrated HR array filter achieved smaller housing dimensions than a no-film HR array filter with the same notch frequency. The transmittance of the film-integrated HR array was theoretically calculated using the transfer matrix method. The calculated spectra were very similar to the simulation results. The notch frequency of the film-integrated HR array filter was 4.04, 0.74 kHz lower than a no-film HR array filter. The design and analysis of the acoustic filter presented should motivate further development of advanced acoustic filters.

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Sensitivity characteristics of a waterproof airflow sensor based on a MEMS piezoresistive cantilever and nanohole array

Hirayama Takuto, Kazoe Yutaka, Takahashi Hidetoshi

JAPANESE JOURNAL OF APPLIED PHYSICS （Japanese Journal of Applied Physics）  62 （ 2 ）  2023年02月

ISSN  0021-4922

　概要を見る

This paper presents the sensitivity characteristics of a microelectromechanical systems (MEMS) piezoresistive cantilever and nanohole array used in a waterproof airflow sensor. Previously, a Pitot tube-type waterproof airflow sensor was developed for seabird biologging. Built-in MEMS piezoresistive cantilevers are used as the differential pressure sensing elements. The waterproof function is achieved using nanohole arrays via Laplace pressure. However, the mechanism underlying sensitivity reduction when nanohole arrays are attached is unclear. Here, we experimentally and theoretically verified that the specific constant, which determines the airflow rate through the cantilever and nanohole array, affects sensitivity reduction. An airflow sensor with a small sensitivity reduction was achieved based on the calculated results using appropriate cantilever and nanohole arrays. We demonstrated that the proposed method for estimating sensitivity reduction is useful for designing waterproof airflow sensors using cantilever-type differential pressure sensor elements.

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Spiral Spring-Supported Force Plate with an External Eddy Current Displacement Sensor

Kawasaki Yuta, Takahashi Hidetoshi

ACTUATORS （Actuators）  12 （ 1 ）  2023年01月

　概要を見る

This study proposes a force plate with a planar spring and an eddy current displacement sensor to measure the ground reaction force (GRF) of a small insect and reveal its motion characteristics. The proposed force plate comprises a circular aluminum plate, four aluminum springs symmetrically connected to the plate, and an eddy current displacement sensor under the plate. The diameter and thickness of the fabricated plate were 8 and 0.1 mm, respectively. The spring width was 0.4 mm. When a force is applied to the plate, the plate moves vertically downward. Then, an eddy current displacement sensor detects the plate displacement without contact. The applied force can be measured using Hooke’s law. The proposed force plate has the advantages of ease of fabrication and cost-effectiveness. The central displacement variation and resonant frequency of the designed springs were evaluated by simulation. Then, we calibrated the fabricated force plate to obtain the sensitivity variation and resonant frequency. The experimental results suggest that the proposed force plate can effectively measure the GRF of a small insect.

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Neural network-based airflow vector sensor using multiple MEMS differential pressure sensors

K Haneda, K Matsudaira, H Takahashi

IEEE Access 11   40978 - 40987 2023年

　概要を見る

As airflow information is significant in various fields, several airflow measurement devices have been developed. Differential pressure (DP)-type sensors, including pitot tubes, are extensively used because they can directly measure dynamic pressure due to airflow. However, this method has a disadvantage in that it is difficult to measure some wind directions because of the non-monotonic pressure distribution around the device. This study proposes a compact sphere airflow vector sensor using a neural network model that compensates for nonmonotonicity. It consists of three built-in microelectromechanical system (MEMS)-based DP sensor elements that simultaneously measure the DPs around the spherical sensor housing. The measured DPs are converted into 2D wind speed and direction using a neural network. The network model was trained using the simulated output of each sensor, and it was confirmed that the proposed design guideline contributed to achieving high accuracy. An airflow sensor was fabricated on the basis of the designed model. A network model was trained using the sensor responses in a wind tunnel experiment. The wind speed and direction accuracies obtained by the neural network model for 2-10 m/s and 0°-359° were 0.24 m/s and 3.62°, respectively. Finally, we demonstrated a drone flight test by attaching the calibrated sensor to a toy drone. This study is expected to contribute to realizing highly accurate low airflow measurement devices.

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MULTI-MEMS DIFFERENTIAL PRESSURE SENSOR ELEMENTS-BASED AIRFLOW SENSOR WITH NEURAL NETWORK MODEL

Haneda Kotaro, Matsudaira Kenei, Takahashi Hidetoshi

2023 IEEE 36TH INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, MEMS （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2023-January   499 - 502 2023年

ISSN  1084-6999

　概要を見る

This paper reports a compact spherical airflow sensor using multi-MEMS differential pressure (DP) sensor elements. Three built-in MEMS sensors simultaneously measure the DP around the spherical housing structure so that the measured DPs are converted into 2D wind direction and speed. The sensor outputs are converted into wind direction and speed by neural network. We attached the calibrated sensor to a toy drone as a demonstration. Then, it was confirmed that the output corresponding to wind direction and speed was measured when a crosswind was applied during flight.

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LIQUID-IMMERSION INCLINED-ROTATED UV LITHOGRAPHY FOR MICRO SUCTION CUP ARRAY

Kagawa Gakuto, Takahashi Hidetoshi

2023 IEEE 36TH INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, MEMS （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2023-January   610 - 612 2023年

ISSN  1084-6999

　概要を見る

This paper reports liquid-immersion inclined/rotated UV lithography for fabricating micro suction cups. Microstructures such as micro suction cups have been applied in various applications. However, the conventional fabrication method had limitations in suction force due to the insufficient inclination angle. We proposed liquid-immersion to inclined/rotated exposure (IRE), enabling greater microstructure inclination angles. IRE equipment was developed to fabricate PDMS micro suction cup arrays. The experimental inclination angle reached 51°, nearly doubling the conventional IRE method.

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LIG-BASED TRIAXIAL TACTILE SENSOR UTILIZING ROTATIONAL ERECTION SYSTEM

Nakashima Rihachiro, Nakamura Nagi, Sano Tomohiko G., Iwase Eiji, Takahashi Hidetoshi

2023 IEEE 36TH INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, MEMS （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2023-January   221 - 224 2023年

ISSN  1084-6999

　概要を見る

This paper reports a laser-induced graphene (LIG)based triaxial tactile sensor utilizing rotational erection system (RES). The proposed process realizes a sensing element with a piezoresistive layer by irradiating a polyimide (PI) film with two types of lasers only once each. Furthermore, the sensing element formed with origami/kirigami method maintains a three-dimensional structure by applying a single external force. The prototype triaxial tactile sensor fabricated by the proposed fabrication process responded independently to normal and shear forces.

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HIGHLY SENSITIVE WAVE HEIGHT SENSOR WITH MEMS PIEZORESISTIVE CANTILEVER AND WATERPROOF MEMBRANE

Hirayama Takuto, Takahashi Hidetoshi

2023 IEEE 36TH INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, MEMS    760 - 762 2023年

ISSN  1084-6999

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Highly Sensitive Low-Frequency-Detectable Acoustic Sensor Using a Piezoresistive Cantilever for Health Monitoring Applications

Y Okamoto, TV Nguyen, H Takahashi, Y Takei, H Okada, M Ichiki

Scientific reports 13 (1), 6503 （Scientific Reports）  13 （ 1 ）  2023年

　概要を見る

This study investigates a cantilever-based pressure sensor that can achieve a resolution of approximately 0.2 mPa, over the frequency range of 0.1–250 Hz. A piezoresistive cantilever with ultra-high acoustic compliance is used as the sensing element in the proposed pressure sensor. We achieved a cantilever with a sensitivity of approximately 40 times higher than that of the previous cantilever device by realizing an ultrathin (340 nm thick) structure with large pads and narrow hinges. Based on the measurement results, the proposed pressure sensor can measure acoustic signals with frequencies as low as 0.1 Hz. The proposed pressure sensor can be used to measure low-frequency pressure and sound, which is crucial for various applications, including photoacoustic-based gas/chemical sensing and monitoring of physiological parameters and natural disasters. We demonstrate the measurement of heart sounds with a high SNR of 58 dB. We believe the proposed microphone will be used in various applications, such as wearable health monitoring, monitoring of natural disasters, and realization of high-resolution photoacoustic-based gas sensors. We successfully measured the first (S1) and second (S2) cardiac sounds with frequencies of 7–100 Hz and 20–45 Hz, respectively.

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Thin Glass Micro Force Plate Supported by Planar Spiral Springs for Measuring Minute Forces

T Kiriyama, K Shimazaki, R Nakashima, H Takahashi

Micromachines 14 (5), 1056 （Micromachines）  14 （ 5 ）  2023年

　概要を見る

Microforce plates are indispensable tools for quantitatively evaluating the behavior of small objects such as tiny insects or microdroplets. The two main measurement principles for microforce plates are: the formation of strain gauges on the beam that supports the plate and the measurement of the deformation of the plate using an external displacement meter. The latter method is characterized by its ease of fabrication and durability as strain concentration is not required. To enhance the sensitivity of the latter type of force plates with a planar structure, thinner plates are generally desired. However, brittle material force plates that are both thin and large and can be fabricated easily have not yet been developed. In this study, a force plate consisting of a thin glass plate with a planar spiral spring structure and a laser displacement meter placed under the plate center is proposed. The plate deforms downward when a force is exerted vertically on its surface, resulting in the determination of the applied force using Hooke’s law. The force plate structure is easily fabricated by laser processing combined with the microelectromechanical system (MEMS) process. The fabricated force plate has a radius and thickness of 10 mm and 25 µm, respectively, with four supporting spiral beams of sub-millimeter width. A fabricated force plate featuring a sub-N/m spring constant achieves a resolution of approximately 0.01 µN.

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Triaxial tactile sensor using RES structure and standing LIG cantilevers

R NAKASHIMA, T SANO, N NAKAMURA, E IWASE, H TAKAHASHI

センサ・マイクロマシンと応用システムシンポジウム (CD-ROM) 40, 3-4 2023年

Triaxial piezoresistive force sensor probe with high sensitivity and stiffness using 3D notch structure

H Takahashi, Y Takei, K Noda, K Matsumoto, I Shimoyama

Journal of Micromechanics and Microengineering 33 (12), 125005 （Journal of Micromechanics and Microengineering）  33 （ 12 ）  2023年

ISSN  09601317

　概要を見る

This paper proposes a microelectromechanical system triaxial piezoresistive force sensor probe with high sensitivity and stiffness. The sensor probe is composed of a cantilever and four supporting beams. Two of the four beams had horizontal notch parts at the root, and sidewall-doped piezoresistors were utilised to detect the in-plane deformation. There was a vertical notch at the root of the remaining two beams and a surface-doping piezoresistor in one beam to detect the out-of-plane deformation. Thus, the proposed sensor probe measures the three directional forces applied to the cantilever tip with high sensitivity and stiffness owing to the corresponding piezoresistive notch structures. We demonstrate a fabrication process that forms the notch structure and the surface and sidewall doping methods. Our fabricated device was confirmed capable of measuring triaxial forces with a force resolution at the sub-micro-Newton level.

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Single step fabrication of a triaxial force plate using 3D printer

Y NAKAHARA, H TAKAHASHI

センサ・マイクロマシンと応用システムシンポジウム (CD-ROM) 40, 5-31 2023年

Simple hearing test utilizing a soundproofing headphone with acoustic filters

F Mizukoshi, N Oishi, H Takahashi

Biomedical Engineering Advances 6, 100102 2023年

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