論文 - 高橋　英俊

Airflow Sensor Using MEMS Differential Pressure Sensors and Neural Network

KENEI MATSUDAIRA, K HANEDA, 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) 40, 5-30 2023年

Two-dimensional waterflow sensor using multiple absolute pressure sensors

K Shimada, T Kishimoto, H Tanaka, H Takahashi

2023 IEEE SENSORS, 1-4 2023年

ISSN  19300395

　概要を見る

This study reports a two-dimensional (2D) waterflow sensor for marine aquaculture. In recent years, environmental monitoring has been widely developed in marine aquaculture. Among these monitoring, ocean currents are one of the important factors in capturing the inflow of hypoxic water into fish cages. However, there were no low-power, simple waterflow sensors that could be adapted to fish cages. Here we propose a waterflow sensor using with a cylindrical housing and an array of six absolute pressure sensor elements to measure 2D waterflow velocity around a fish cage. 2D waterflow velocity is calculated via a polynomial regression model of the responses of six pressure sensors and sensor tilt angle. By constructing the model for each tilt angle, the developed sensor responded with sufficient sensitivity to waterflow velocities from 0.4 to 2.0 m/s.

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Pressure sensor with a corrugated structure utilizing LIG sensing element

R Oda, R Nakashima, H Takahashi

2023 22nd International Conference on Solid-State Sensors, Actuators and …    1601 - 1603 2023年

　概要を見る

This paper reports on a pressure sensor with a corrugated structure utilizing a laser-induced graphene (LIG) strain gauge. A concentrically expanding corrugated structure is formed on a polyimide (PI) film by a UV laser. A LIG layer, which function as a piezoresistor, is directly formed by a CO2 laser to the outermost circumference of the corrugated structure. Using two different-types laser processing, a highly sensitive pressure sensor is easily realized. Here we theoretically and experimentally show the proposed method usefulness by evaluating the sensor response.

Pitot-Type Waterflow Sensor Logger for Relative Waterflow Velocity Measurement of a Sea Turtle

T Kishimoto, R Saito, H Tanaka, M Naruoka, K Kuroda, K Sato, ...

2023 22nd International Conference on Solid-State Sensors, Actuators and …    698 - 701 2023年

　概要を見る

This study presents a waterflow sensor logger for sea turtles. Many sensors have been attached to wild animals via the biologging method for animal ecological analysis. However, it is not easy to measure the relative waterflow velocity of marine animals with a conventional sensor due to marine debris and algae. Furthermore, there are limited examples of measurements for sea turtles. Here, we proposed a Pitot-type waterflow sensor logger. The sensor logger achieves both resistance to algae and marine debris and pressure resistance because of the Pitot-type waterflow sensor structure. Attaching the sensor logger to a sea turtle's carapace will make long-term velocity measurement possible. The fabricated sensor logger responded stably to waterflow and measured actual sea turtle's swimming as waterflow velocity.

Pitot Tube Type Compact Waterproof Airflow Sensor for Seabird Biologging

T Hirayama, T Kishimoto, H Takahashi

2023 IEEE SENSORS, 1-4 2023年

ISSN  19300395

　概要を見る

In this study, a waterproof airflow sensor is proposed for seabird biologging. Biologging, in which a sensor is directly attached to an animal to record its behavior, has attracted much attention to assess the animal's locomotion performance. Among them, it has been focused to evaluate the flight performance of seabirds. An airflow sensor becomes a powerful tool to measure the self-induced flight velocity of a seabird, however, the sensor is also required to have water pressure resistance. Here we propose a Pitot tube type compact waterproof airflow sensor with micromesh filters for seabird biologging. The Pitot tube structure with built-in the differential pressure sensor element realized a compact and robust sensor performance. The micro-mesh filter was attached to the air inlets to achieve high water pressure resistance. The developed sensor responded with high sensitivity to pressures up to 100 Pa and airflow up to 10 m/s without any loss of sensitivity caused by the filter.

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One Step Fabrication of Triaxial Force Plate Using a FDM 3D Printer

Y Nakahara, H Takahashi

2023 22nd International Conference on Solid-State Sensors, Actuators and …    1759 - 1761 2023年

　概要を見る

This paper reports a triaxial force plate which is entirely fabricated in a single step with a fused deposition modeling (FDM) 3D printer. The force plate consists of strain gauges and body structure. The strain gauges measure the force by fractional resistance changes, which is printed with electrical conductive poly-lactic acid (EC PLA). 3D printers specialize in forming three-dimensional parts, it can create multiple strain gauges of complex shapes simultaneously without any specific jigs such as photo masks. The body structure has a plate and pillars, which strain uniquely in response to the loaded triaxial forces. The prototype force plate fabricated by the proposed fabrication method was confirmed to respond independently to vertical and horizontal forces.

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.

2023 22nd International Conference on Solid-State Sensors, Actuators and Microsystems, Transducers 2023    1591 - 1594 2023年

　概要を見る

This paper reports the development of a nest box in which changes in the mass and heart rate of a growing seabird chick can be simultaneously measured. The nest box is equipped with two scales and a heart rate monitor. By using two scales, zero-point drift is expected to be suppressed. A non-contact displacement sensor that has environmental resistance is used as the sensor element for the scales. As a heart monitor, a tube with one end closed and the other end connected to a pressure sensor is used. The developed nest box will allow non-invasive, sequential measurement of the mass and heart rate of chicks over a long time.

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

T Kishimoto, M Agetsuma, A Hoshino, H Takahashi

Electronics and Communications in Japan 106 (3), e12420 2023年

Needle-Type Pressure Sensor with Silicone Oil and Parylene Membrane inside for Minimally Invasive Measurement

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

IEEJ Transactions on Sensors and Micromachines 143 （ 7 ） 148 - 155 2023年

ISSN  13418939

　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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MEMS Differential Pressure Sensor with Dynamic Pressure Canceler for Precision Altitude Estimation

S Yasunaga, H Takahashi, T Takahata, I Shimoyama

Micromachines 14 (10), 1941 14 （ 10 ）  2023年

　概要を見る

Atmospheric pressure measurements based on microelectromechanical systems (MEMSs) can extend accessibility to altitude information. A differential pressure sensor using a thin cantilever and an air chamber is a promising sensing element for sub-centimeter resolution. However, its vulnerability to wind and the lack of height estimation algorithms for real-time operation are issues that remain to be solved. We propose a sensor “cap” that cancels the wind effect and noise by utilizing the airflow around a sphere. A set of holes on the spherical cap transmits only the atmospheric pressure to the sensor. In addition, we have developed a height estimation method based on a discrete transfer function model. As a result, both dynamic pressure and noise are suppressed, and height is estimated under a 5 m/s wind, reconstructing the trajectory with an estimation error of 2.8 cm. The developed sensing system enhances height information in outdoor applications such as unmanned aerial vehicles and wave height measurements.

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MEMS 6-axis force sensor chip for spike pins in athletic sports shoes

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

Sensors and Actuators A: Physical 363, 114702 363 2023年

ISSN  09244247

　概要を見る

This study reports a microelectromechanical system (MEMS) sensor for evaluating the force acting on the spike pins of athletic sports shoes. The ground reaction force (GRF) of the human sole is a crucial factor in understanding running mechanics. In short-distance sprints, running is achieved by biting the ground using shoe spikes. However, it is difficult to evaluate the forces acting on such spike pins because of their small size. In this study, a MEMS sensor chip that could measure the 6-axis forces was embedded in an actual spike-pin-shaped structure, and the fabricated spike pin was attached to athletic shoes. By utilizing four pairs of surface- and sidewall-doped beams as sensing elements, the 6-axis force acting on the pin can be measured regardless of the force distribution when the pin bites into the track. We demonstrated that the force distribution could be measured using three sensors developed during running. The vertical force on each pin exceeded 100 N. Furthermore, it was observed that higher propulsive forces were exerted on all the spike pins in the first step compared to the second step or later steps. Therefore, the proposed method can be used to evaluate running mechanics using spike pins in athletic sports shoes.

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Liquid-immersion inclined UV lithography using cube prism and mirrors

Kagawa Gakuto, Sugimoto Takumi, Takahashi Hidetoshi

APPLIED PHYSICS EXPRESS （Applied Physics Express）  15 （ 11 ）  2022年11月

ISSN  1882-0778

　概要を見る

This paper reports on the inclined UV lithography based on liquid immersion. The proposed method implements liquid immersion, allowing structures to be formed with a large inclination angle. The equipment comprises two adjustable mirrors and a cubic glass with a pure water chamber. UV light rays are reflected and passed through the mirrors and chamber, irradiating the target at an inclined angle. We developed the necessary equipment and fabricated the 3D microstructures. The results revealed that the inclination angle reached up to 49°, indicating exposures beyond the limits of conventional inclined UV lithography.

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A Polyimide Film-Based Simple Force Plate for Measuring the Body Mass of Tiny Insects

Shimazaki Kenichiro, Sugimoto Takumi, Toda Hirofumi, Takahashi Hidetoshi

SENSORS （Sensors）  22 （ 21 ）  2022年11月

ISSN  14248220

　概要を見る

Insects exhibit excellent maneuvers such as running and flying despite their small bodies; therefore, their locomotion mechanism is expected to provide a design guideline for micromachines. Numerical simulations have been performed to elucidate this mechanism, whereby it is important to develop a model that is physically identical to the target insect’s parts to reproduce kinematic dynamics. In particular, in flight, the shape and mass of wings, which flap at high frequencies, are significant parameters. However, small insects such as fruit flies have small, thin, and light wings; thus, their mass cannot be easily measured. In this study, we proposed a high-resolution and simple force plate to measure the mass of each part of a tiny insect. The device consists of a circular plate supported by flat spiral springs made of polyimide film, and a laser displacement meter that detects the displacement of the center of the plate. The simple plate fabrication process requires only a couple of minutes. A fabricated force plate with a sub-N/m spring constant achieved a resolution of less than 2 µg. As a demonstration, the wing mass of the fruit flies was measured. The experimental results suggest that the wings accounted for approximately 0.4% of the body mass.

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Frequency-specific highly sensitive acoustic sensor using a piezoresistive cantilever element and parallel Helmholtz resonators

Wada Ruka, Takahashi Hidetoshi

SENSORS AND ACTUATORS A-PHYSICAL （Sensors and Actuators A: Physical）  345 2022年10月

ISSN  0924-4247

　概要を見る

Acoustic sensors for specific-frequency detection are used in various applications, and their sensitivity improvement has been attracting significant attention. Mechanical acoustic resonator technology is an effective method because of its simple structure and low power consumption. A Helmholtz resonator (HR) is a typical mechanical resonator; however, previous HRs for an acoustic sensor were attached to the rear of the sensing element, which was unsuitable for a differential pressure (DP) sensor that blocks the pressure wave propagating through the sensor chip. This paper proposes a micro-electro-mechanical system (MEMS)-based acoustic sensor, enhanced by a front-mounted parallel HR array, which is suitable for a DP sensor-type element. A piezoresistive cantilever-type DP sensor was used as the sensing element because of its high sensitivity to acoustic waves in its mechanical resonant frequency (RF) range. Its sensitivity was enhanced by attaching an HR array to the DP sensor, like a cap. We designed and fabricated a piezoresistive cantilever with dimensions 80 × 80 × 0.2 µm and an RF of 4.5 kHz, and four HR arrays with an RF close to that of the cantilever. The sensor responses to acoustic waves with and without the HRs were evaluated. The developed sensor with the HR realized three times higher sensitivity than those without the HR at the RF. The obtained acoustic pressure resolution was approximately 4 mPa.

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Measurement method of a microspring-supported force plate with an external laser displacement meter

Sugimoto Takumi, Kawasaki Yuta, Toda Hirofumi, Takahashi Hidetoshi

MEASUREMENT SCIENCE AND TECHNOLOGY （Measurement Science and Technology）  33 （ 10 ）  2022年10月

ISSN  0957-0233

　概要を見る

Ground reaction force (GRF) is a significant factor for the evaluation of animal locomotion. Recently, micro force plates have been implemented as a GRF measurement method for tiny insects. Previous micro force plates were highly sensitive, but fragile and laborious to fabricate, because of the use of strain-sensing elements. Here, we applied high-resolution 3D printing and a noncontact displacement meter to a micro force plate for a fruit fly. 3D printing is suitable for easier, reproducible, and complex three-dimensional fabrication so that a force plate structure, which consists of a plate and four supporting 3D microsprings, is developed as an integrated unit. By detecting the displacement of the plate centre externally, when a fruit fly lands on the plate surface, the vertical GRF of the whole device is calculated via the spring constant. The force plate is sufficiently tough due to the supporting 3D microsprings. The spring constant of the microspring is designed to be approximately 5.98 N m−1, which enables a high-resolution external laser displacement meter to realize a force resolution of less than 1/50 of the body weight of a fruit fly. Providing that the four springs have the same spring constant and the displacement meter aligns at the plate centre, in principle, there is no positional error when converting from displacement to force. However, fabrication error does lead to spring constant differences. Here, we theoretically and experimentally determined the measurement point of the displacement sensor where the positional error caused by the difference in the spring constant of the four microsprings is compensated for. It was confirmed in the experiment that the calibration process improved the position error to be within ±1.5%. Finally, we demonstrated the GRF measurement of a fruit fly. The average GRF was 6.5 μN, which was equal to the weight of a fruit fly. Our proposed device can help evaluate the biomechanics of tiny insects.

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MEMS-Based Micro Sensors for Measuring the Tiny Forces Acting on Insects

Takahashi Hidetoshi

SENSORS （Sensors）  22 （ 20 ）  2022年10月

ISSN  14248220

　概要を見る

Small insects perform agile locomotion, such as running, jumping, and flying. Recently, many robots, inspired by such insect performance, have been developed and are expected to be smaller and more maneuverable than conventional robots. For the development of insect-inspired robots, understanding the mechanical dynamics of the target insect is important. However, evaluating the dynamics via conventional commercialized force sensors is difficult because the exerted force and insect itself are tiny in strength and size. Here, we review force sensor devices, especially fabricated for measuring the tiny forces acting on insects during locomotion. As the force sensor, micro-force plates for measuring the ground reaction force and micro-force probes for measuring the flying force have mainly been developed. In addition, many such sensors have been fabricated via a microelectromechanical system (MEMS) process, due to the process precision and high sensitivity. In this review, we focus on the sensing principle, design guide, fabrication process, and measurement method of each sensor, as well as the technical challenges in each method. Finally, the common process flow of the development of specialized MEMS sensors is briefly discussed.

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Frequency Characteristics of Pulse Wave Sensor Using MEMS Piezoresistive Cantilever Element

Nabeshima Taiga, Nguyen Thanh-Vinh, Takahashi Hidetoshi

MICROMACHINES （Micromachines）  13 （ 5 ） 645 - 645 2022年05月

　概要を見る

Wearable sensor devices with minimal discomfort to the wearer have been widely developed to realize continuous measurements of vital signs (body temperature, blood pressure, respiration rate, and pulse wave) in many applications across various fields, such as healthcare and sports. Among them, microelectromechanical systems (MEMS)-based differential pressure sensors have garnered attention as a tool for measuring pulse waves with weak skin tightening. Using a MEMS-based piezoresistive cantilever with an air chamber as the pressure change sensor enables highly sensitive pulse-wave measurements to be achieved. Furthermore, the initial static pressure when attaching the sensor to the skin is physically excluded because of air leakage around the cantilever, which serves as a high-pass filter. However, if the frequency characteristics of this mechanical high-pass filter are not appropriately designed, then the essential information of the pulse-wave measurement may not be reflected. In this study, the frequency characteristics of a sensor structure is derived theoretically based on the air leakage rate and chamber size. Subsequently, a pulse wave sensor with a MEMS piezoresistive cantilever element, two air chambers, and a skin-contacted membrane is designed and fabricated. The developed sensor is 30 mm in diameter and 8 mm in thickness and realizes high-pass filter characteristics of 0.7 Hz. Finally, pulse wave measurement at the neck of a participant is demonstrated using the developed sensor. It is confirmed that the measured pulse wave contains signals in the designed frequency band.

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Compact Sphere-Shaped Airflow Vector Sensor Based on MEMS Differential Pressure Sensors

Haneda Kotaro, Matsudaira Kenei, Noda Ryusuke, Nakata Toshiyuki, Suzuki Satoshi, Liu Hao, Takahashi Hidetoshi

SENSORS （Sensors）  22 （ 3 ） 1087 - 1087 2022年02月

ISSN  14248220

　概要を見る

This paper presents an airflow vector sensor for drones. Drones are expected to play a role in various industrial fields. However, the further improvement of flight stability is a significant issue. In particular, compact drones are more affected by wind during flight. Thus, it is desirable to detect air current directly by an airflow sensor and feedback to the control. In the case of a drone in flight, the sensor should detect wind velocity and direction, particularly in the horizontal direction, for a sudden crosswind. In addition, the sensor must also be small, light, and highly sensitive. Here, we propose a compact spherical airflow sensor for drones. Three highly sensitive microelectro mechanical system (MEMS) differential pressure (DP) sensor chips were built in the spherical housing as the sensor elements. The 2D wind direction and velocity can be measured from these sensor elements. The fabricated airflow sensor was attached to a small toy drone. It was demonstrated that the sensor provided an output corresponding to the wind velocity and direction when horizontal wind was applied via a fan while the drone was flying. The experimental results demonstrate that the proposed sensor will be helpful for directly measuring the air current for a drone in flight.

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ANGULAR ACCELEROMETER WITH INTEGRATED LIQUID SPIRAL CHANNEL AND LIG SENSING ELEMENT ON POLYIMIDE FILM

Nakashima Rihachiro, Takahashi Hidetoshi

2022 IEEE 35TH INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS CONFERENCE (MEMS) （IEEE Symposium on Mass Storage Systems and Technologies）  2022-January   747 - 749 2022年

ISSN  1084-6999

　概要を見る

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年