Details of a Researcher - Takahashi, Hidetoshi

Papers - Takahashi, Hidetoshi

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Angular Accelerometer with Integrated Liquid Spiral Channel and lig Sensing Element on Polyimide Film

R Nakashima, H Takahashi

2022 IEEE 35th International Conference on Micro Electro Mechanical Systems … (IEEE Symposium on Mass Storage Systems and Technologies) 2022-January 747 - 749 2022

ISSN 1084-6999

This paper reports on the fabrication method of an angular accelerometer with integrated liquid spiral channels and laser-induced graphene (LIG) sensing element. The proposed fabrication process forms the LIG sensing element and the spiral grooves via a CO2 laser and a UV laser, respectively, on a polyimide (PI) film. The liquid-sealed spiral channels are fabricated by filling the grooves with silicone oil and applying parylene deposition. Thus, the fabrication process is quite ple. The prototype sensor was validated for its response to angular acceleration.

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An experiment to distinguish persistent infrasounds from two fumaroles at Kirishima Iwo-Yama

K Yamakawa, M Ichihara, D Muramatsu, T Matsushima, H Takahashi, ...

2022

A Tunable Open Planar Acoustic Notch Filter Utilizing a Pneumatically Modulated Helmholtz Resonator Array

F Mizukoshi, H Takahashi

IEEE Access 10, 118213-118221 (IEEE Access) 10 118213 - 118221 2022

ISSN 2169-3536

Acoustic filters provide sound insulation unpleasant noises at a specific frequency only. Ordinary passive acoustic filters made up of acoustic metamaterial structures can work without a power supply. However, their working frequency is not adjustable. This study reports a tunable open planar acoustic notch filter that incorporates a pneumatically controlled Helmholtz resonator (HR) array. The HR array consisted of three layers: cavities, a membrane, and microchannels. The cavities function as the HR chambers, whose volume determines the resonant frequency. The acoustic wave is effectively attenuated at this frequency owing to the HR effect. The HR chamber volume can be varied by displacing the stretchable membrane with air pressure through the microchannels. This helps in adjusting the resonant frequency, thereby realizing a tunable acoustic notch filter. We conducted theoretical, and experimental examinations along with simulations of the frequency response for an HR array with three different cavity thicknesses. The prototype device realized a frequency tuning of approximately 4.1-4.9 kHz with 10 dB filtering. Furthermore, an improved notch frequency tunability was observed for the thinner cavities, along with a decrease in the notch performance. Thus, the proposed HR array filter can be useful for high-frequency noise that is generally uncomfortable for humans.

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Needle type pressure sensor using MEMS piezoresistive cantilever

T KISHIMOTO, 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) 39, 2-3 2022

力センサの研究開発とその応用 [塾内限定]

H Takahashi

慶應義塾大学理工学部 2022

Force plate with simple mechanical springs and separated noncontact sensor elements

Y Kawasaki, A Ogawa, H Takahashi

Sensors 21 (21), 7092 (Sensors) 21 ( 21 ) 2021.11

ISSN 14248220

This paper reports on a force plate (FP) using mechanical springs and noncontact distance sensors. The ground reaction force (GRF) is one of the factors for clarify biomechanics, and FPs are widely used to measure it. The sensor elements of conventional FPs are mainly strain gauges. Thus, the mechanical properties of FP depend on the sensor element performance. If the FP performance must change, we must redesign the FP, including changing the sensor elements. Here, we proposed an FP that uses a measuring principle based on simple springs and noncontact sensors. The shape and performance of the proposed FP are expected to change easily. As a prototype device, we designed and fabricated an FP installed with 12 springs and four sensors for human walking. A planar coil and magnet were used as the sensor elements, and the sensor output was proportional to the vertical and horizontal displacements. The FP resonance frequency was 123 Hz, which was larger than the required specification. The calibration experiments showed that vertical and horizontal forces and moments could be measured independently. The FP’s resolutions were 1.9 N and 1.4 N in the anterior–posterior and vertical directions, respectively. Furthermore, the fabricated FP measured GRF similarly to the commercial FP when a human walked on the plate. These results suggest that the proposed method will be helpful for FPs with custom-made requirements.

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Acoustic notch filtering earmuff utilizing Helmholtz resonator arrays

F Mizukoshi, H Takahashi

PloS one 16 (10), e0258842 (PLoS ONE) 16 ( 10 ) 2021.10

ISSN 1932-6203

In recent years, noisy bustling environments have created situations in which earmuffs must soundproof only specific noise while transmitting significant sounds, such as voices, for work safety and efficiency. Two sound insulation technologies have been utilized: passive noise control (PNC) and active noise control (ANC). However, PNC is incapable of insulating selective frequencies of noise, and ANC is limited to low-frequency sounds. Thus, it has been difficult for traditional earmuffs to cancel out only high-frequency noise that people feel uncomfortable hearing. Here, we propose an acoustic notch filtering earmuff utilizing Helmholtz resonator (HR) arrays that provides a sound attenuation effect around the tuneable resonant frequency. A sheet-like sound insulating plate comprising HR arrays is realized in a honeycomb structure. Since the resonant frequency is determined by the geometry of the HR arrays, a highly audible sound region can be designed as the target frequency. In this research, the acoustic notch filtering performance of the proposed HR array plate is investigated in both simulations and experiments. Furthermore, the fabricated earmuffs using the novel HR array plates achieve a sound insulation performance exceeding 40 dB at the target frequency, which is sufficiently high compared to that of conventional earmuffs. The experimental results confirm that the proposed device is a useful approach for insulating frequency-selective sound.

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Pitot-static-tube-based waterflow sensor for marine biologging via inside sealing of an incompressible liquid

T Kishimoto, R Saito, H Tanaka, H Takahashi

IEEE Sensors Journal 21 (18), 19806-19814 (Institute of Electrical and Electronics Engineers ({IEEE})) 21 ( 18 ) 19806 - 19814 2021.09

ISSN 1530-437X

This article presents a waterflow sensor for marine biologging. Although biologging methods have attracted attention in evaluating marine animals' swimming performance, it has been difficult to directly measure the long-term waterflow velocity against a swimming animal. This is because the sensors require strict specifications, such as sufficient sensitivity and accuracy, small size and light weight, ability to move between water and air for breathing, and sufficient water pressure resistance. Here, we propose a waterflow sensor based on a closed-inlet Pitot-static tube structure that satisfies these requirements. The tube is filled with incompressible liquid. Silicone membranes are attached to the inlets to prevent air bubble infiltration. A differential pressure sensor chip, which works as the Pitot-static tube's sensing element, is built into the tube housing to measure the pressure difference between the inlets. Due to the fluid incompressibility, the required pressure resistance is realized. The developed sensor responded to waterflow from 0.2 m/s to 1.6 m/s with sufficiently high sensitivity. Therefore, the proposed sensor can be utilized for the biologging of marine animals.

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Seabird biologging system with compact waterproof airflow sensor

H Takahashi, M Naruoka, Y Inada, K Sato

Journal of Robotics and Mechatronics 33 (3), 466-474 (Journal of Robotics and Mechatronics) 33 ( 3 ) 466 - 474 2021.06

ISSN 0915-3942

This paper presents a seabird biologging system with a compact waterproof airflow sensor. Although biolog-ging methods have attracted attention in the evaluation of seabird flight performance, a direct measurement method of airflow velocity has not yet been es-tablished. When an airflow sensor is added to a bi-ologging system, a more accurate assessment of the flight performance can be obtained. We developed a compact Pitot tube-type airflow sensor that is special-ized for seabird biologging systems. Here, we integrated micro electro mechanical system (MEMS) sensor chips and a sensing circuit into the Pitot tube hous-ing. Then, we conducted a wind tunnel experiment using a stuffed seabird and the fabricated sensor. The results confirmed that the sensor responds to the wind speed even when attached to the dorsal surface of the seabird. Based on the above, we believe that the proposed sensor can be applied to practical seabird bi-ologging systems.

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Biaxial angular acceleration sensor with rotational-symmetric spiral channels and MEMS piezoresistive cantilevers

R Nakashima, H Takahashi

Micromachines 12 (5), 507 (Micromachines) 12 ( 5 ) 2021.05

Angular acceleration sensors are attracting attention as sensors for monitoring rotational vibration. Many angular acceleration sensors have been developed; however, multiaxis measurement is still in a challenging stage. In this study, we propose a biaxial angular acceleration sensor with two uniaxial sensor units arranged orthogonally. The sensor units consist of two rotationalsymmetric spiral channels and microelectromechanical system (MEMS) piezoresistive cantilevers. The cantilever is placed to interrupt the flow at the junctions of parallelly aligned spirals in each channel. When two cantilevers are used as the resistance of the bridge circuit in the two-gauge method, the rotational-symmetric spiral channels enhance the sensitivity in the target axis, while the nontarget axis sensitivities are canceled. The fabricated device responds with approximately constant sensitivity from 1 to 15 Hz, with a value of 3.86 × 10-5/(rad/s2), which is equal to the theoretical value. The nontarget axis sensitivity is approximately 1/400 of the target axis sensitivity. In addition, we demonstrate that each unit responds according to the tilt angle when the device is tilted along the two corresponding rotational axis planes. Thus, it is concluded that the developed device realizes biaxial angular acceleration measurement with low crosstalk.

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An angular accelerometer with high sensitivity and low crosstalk utilizing a piezoresistive cantilever and spiral liquid channels

B Jo, H Takahashi, T Takahata, I Shimoyama

IEEE Sensors Journal 21 (3), 2687-2692 (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC) 21 ( 3 ) 2687 - 2692 2021.02

ISSN 1530-437X

This article describes an angular accelerometer with high sensitivity and low crosstalk that uses a MEMS (Micro Electro Mechanical Systems) piezoresistive cantilever and spiral liquid channels. The fabricated device is composed of two spiral channels aligned in parallel with the piezoresistive cantilever placed in between the channels. When angular acceleration is applied, the liquid inside the spiral channels produces an inertial force. This inertial force generates a pressure difference between the spiral channels, and that difference is measured by a piezoresistive cantilever with a high resolution of 0.01 Pa. The pressure difference causes deformation of the piezoresistive cantilever which results in resistance change. Finally, the applied angular acceleration can be calculated from the resistance change. By increasing the number of turns of the spiral channel, both high sensitivity and low crosstalk from the nontarget axis can be achieved. Our proposed device with 12.5 turns achieved a sensitivity of 0.72 mV/(rad/s(2)) and crosstalk of less than 2%.

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Compact Pitot-static-tube-based waterflow sensor for biologging of marine animals

T Kishimoto, R Saito, H Tanaka, H Takahashi

2021 IEEE Sensors, 1-4 (Proceedings of IEEE Sensors) 2021-October 2021

ISSN 1930-0395

This study presents a waterflow sensor for biologging of marine animals. Although a biologging method of recording animal behavior with sensors is attracted attention for evaluating the swimming performance of marine animals, it is not easy to measure waterflow velocity for a long time. This is due to strict requirements such as compact size and high pressure resistance. In addition, marine animals move above the sea surface to breathe. Here, we proposed a compact Pitot-static-tube-based waterflow sensor for biologging of marine animals. Incompressible liquid is sealed inside the sensor housings to realize high-pressure resistance. A thin film is glued inlets of the sensor to prevent air bubbles invention. A membrane-type differential pressure sensor chip is built inside the sensor to measure differential pressure between each inlet. By downsizing the sensor shape and reducing sealed incompressible liquid, the sensor is compacter than a previous sensor. The developed sensor responded to waterflow velocity from 0.2 to1.6 m/s with sufficiently high sensitivity.

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Densely Arrayed Active Antennas Embedded in Vertical Nanoholes for Backside-Illuminated Silicon-Based Broadband Infrared Photodetection

Shun Yasunaga, Hidetoshi Takahashi, Tomoyuki Takahata, Isao Shimoyama, Tetsuo Kan

ADVANCED MATERIALS INTERFACES (WILEY) 7 ( 21 ) 2020.11

ISSN 2196-7350

Plasmonic metal nanoantennas arrayed on silicon have attracted attention as silicon-based sub-bandgap infrared detectors. Localized surface plasmons induced on metal nanoblocks can provide a broadband responsivity, and the silicon-based configuration offers the potential for complementary metal oxide semiconductor-compatible infrared photodetectors. The responsivity of such devices, however, needs further improvement. In this report, a nanoantenna structure consisting of a nanoblock with electrical connection to it built in a narrow, vertical, and deep nanohole is presented, which generates a photocurrent in response to backside illumination. Inclined evaporative deposition of copper onto an array of nanoholes, 150 nm in diameter and 560 nm in depth, simultaneously forms nanoblocks and thin conductive films. The structure's effectiveness is demonstrated from the reflectance and responsivity to infrared laser illumination 1.1-1.8 mu m in wavelength. When the periodicity of the nanoholes is 500 nm, a responsivity of 9.8 mA W(-1)at 1.55 mu m is obtained, which is sustained over a broad band. The responsivity-density relationship has a limitation between periodicities of 250 and 500 nm, possibly because of overlapped near fields around antennas and the resultant altered resonant mode. With its simple fabrication and efficient functionality, the nanoantenna structure contributes to the realization of silicon-based infrared imaging.

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MEMS triaxial gyroscope using surface and sidewall doping piezoresistors

H Takahashi, K Abe, T Takahata, I Shimoyama

Journal of Micromechanics and Microengineering 30 (10), 105012 (IOP PUBLISHING LTD) 30 ( 10 ) 2020.10

ISSN 0960-1317

This paper describes a MEMS triaxial gyroscope utilizing three-dimensional piezoresistive elements. MEMS gyroscopes are widely used for robot motion control, drones, mobile phones and so on. Although a piezoresistive sensing element has the potential for high sensitivity to angular velocity via vibrations that occur due to the Coriolis force, a commonly used piezoresistor, which is formed on a device surface, is not suitable to measure in-plane deformations. Thus, it is difficult to realize a sensing element for a triaxial gyroscope with conventional piezoresistors, especially an element for the detection of vertical axis angular velocity. Here, we propose a triaxial gyroscope utilizing surface and sidewall doping piezoresistors as the sensing element. The surface and sidewall doping piezoresistors detect out-of-plane and in-plane vibrations due to the corresponding three-dimensional Coriolis forces, respectively. As a result, the triaxial angular velocity becomes measurable. The experimental results show that the fabricated gyroscope responds to three-dimensional angular velocities with low crosstalk. Therefore, the proposed gyroscope is suitable for practical angular velocity measurement applications.

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Multidirectional UV lithography via inclined/rotated mirrors for liquid materials

T Sugimito, H Takahashi

Applied Physics Express 13 (7), 076502 (Applied Physics Express) 13 ( 7 ) 2020.07

ISSN 1882-0778

This letter presents the development of an exposure equipment for inclined/rotating lithography with UV curable liquid materials. The proposed equipment is composed of inclined mirrors rotating around exposure spot and shading plate to prevent direct vertical irradiated UV light. UV light ray is reflected on the mirrors, and irradiate to the spot with inclined angle via rotation. During mirrors rotating, UV curable material located on the exposure spot keeps a quiet state. The incident angle of UV light ray is controllable by changing the mirror inclination. We developed an equipment and conducted an experiment for the fabrication of 3D structures with PEGDA.

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Time response characteristics of a highly sensitive barometric pressure change sensor based on MEMS piezoresistive cantilevers

R Wada, H Takahashi

Japanese Journal of Applied Physics 59 (7), 070906 (Japanese Journal of Applied Physics) 59 ( 7 ) 2020.07

ISSN 0021-4922

This paper describes the frequency characteristics of a highly sensitive barometric pressure change sensor. Here, we propose a method to measure pressure changes based on microelectromechanical systems piezoresistive cantilevers and an air chamber. The proposed sensor structure realizes a mechanical high pass filter to eliminate the influence of the barometric pressure change due to meteorological variations. The experimental frequency characteristics indicate that the proposed sensor unit with a high resolution of less than 0.1 Pa from 0.1 to 10 Hz responds to pressure changes with a high pass filter property according to the chamber volume size.

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Self-focusing 3D lithography with varying refractive index polyethylene glycol diacrylate

H Takahashi, T Kan, G Lee, N Dönmez, J Kim, J Park, D Kim, YJ Heo

Applied Physics Express 13 (7), 076503 (IOP PUBLISHING LTD) 13 ( 7 ) 2020.07

ISSN 1882-0778

This work presents self-focusing 3D lithography based on the refractive index changes of polyethylene glycol diacrylate (PEGDA) during photopolymerization. Since the polymerization of PEGDA leads to an increase in the refractive index, the UV light rays in the PEGDA undergo a refraction effect during exposure, thus being focused and forming 3D photopolymerized structures. We demonstrate the potential of self-focusing 3D lithography by fabricating PEGDA microneedles and trapezoid-shaped microwells. Their structures well match our theoretical estimation. Therefore, our theoretical approach can provide a short route to realizing on-demand, complicated 3D structures of refractive-index-variable materials with single UV exposure.

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Micro Water Flow Measurement Using a Temperature-Compensated MEMS Piezoresistive Cantilever

R Pommois, G Furusawa, T Kosuge, S Yasunaga, H Hanawa, ...

Micromachines 11 (7), 647 (MDPI) 11 ( 7 ) 2020.07

In this study, we propose a microelectromechanical system (MEMS) force sensor for microflow measurements. The sensor is equipped with a flow sensing piezoresistive cantilever and a dummy piezoresistive cantilever, which acts as a temperature reference. Since the dummy cantilever is also in the form of a thin cantilever, the temperature environment of the dummy sensor is almost identical to that of the sensing cantilever. The temperature compensation effect was measured, and the piezoresistive cantilever was combined with a gasket jig to enable the direct implementation of the piezoresistive cantilever in a flow tube. The sensor device stably measured flow rates from 20 mu L/s to 400 mu L/s in a silicon tube with a 2-mm inner diameter without being disturbed by temperature fluctuations.

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Reconfigurable Surface Plasmon Resonance Photodetector with a MEMS Deformable Cantilever

M Oshita, H Takahashi, Y Ajiki, T Kan

ACS Photonics (American Chemical Society (ACS)) 7 ( 3 ) 673 - 679 2020

ISSN 2330-4022

Plasmonic photodetectors have many useful characteristics, such as wavelength- or polarization-specific photodetection. Although reconfigurable plasmonic structures have been intensively studied, reconfiguration of the optical characteristics of a plasmonic photodetector has not yet been reported. Here, we report a gold diffraction-grating-type plasmonic photodetector that reconfigures its optical characteristics with a MEMS deformable cantilever. By reconfiguring the photodetector characteristics using an angular scan of the cantilever over -21° to 21°, the peak shifts of the photocurrent signal waveform are found to depend on the wavelength over 1200∼1500 nm, which is consistent with SPR theory. The proposed reconfigurable plasmonic photodetector allowed us to obtain spectroscopic information on the light in a demonstration experiment.

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Pipette Based Viscometer with Pressure Sensor Element

S Cho, TV Nguyen, N Miki, H Takahashi

2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems … (Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)) 2020-January 646 - 648 2020

ISSN 1084-6999

© 2020 IEEE. This paper reports a simple viscometer, whose principle utilizes the relationship between liquid viscosity and the suction speed in a tube. The proposed viscometer is composed of an air chamber and a glass tube. A steel ball is attached to the silicone membrane of the chamber and an electromagnetic magnet is used to provide the volume change. A MEMS pressure sensor element is attached to the chamber to measure its pressure change. When a step-response volume change is applied, the chamber pressure decreases so that the liquid sticking to the tube gradually ascends at a speed depending to the viscosity. Thus, the viscosity can be calculated by measuring the gradient of the pressure change. The proposed method can be applied to micropipettes so that viscosity is easily measured with a simple device.

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