Papers - Takahashi, Hidetoshi

Triaxial Microforce Plate Array for Measuring Reaction Force Distribution of Ants Walking on Ground and Wall

T Shiratori, H Takahashi

2026 IEEE 39th International Conference on Micro Electro Mechanical Systems …  2026

Sensor System for Gas Source Localization Integrating A Compact 3D Wind Vector Sensor and Gas Sensor

R Ando, H Takahashi

2026 IEEE 39th International Conference on Micro Electro Mechanical Systems …  2026

Acoustically driven MEMS mirror enhanced by a parallel Helmholtz resonator array

M Fukuta, R Nakashima, T Kan, H Takahashi

Journal of Micromechanics and Microengineering  2026

• Access to Document (DOI)

Dual-Axis Acoustically Driven Mems Mirror with a Parallel Double-Layered Helmholtz Resonator Array

M Fukuta, H Takahashi

2026 IEEE 39th International Conference on Micro Electro Mechanical Systems …  2026

Optimizing resolution in force plate using the sampling moiré method

O Nomura, A Ogawa, H Takahashi

Japanese Journal of Applied Physics  2026

• Access to Document (DOI)

Piezoresistive cantilever for in-plane force measurement using liquid-immersion laser sidewall doping

R Nakashima, Y Okamoto, Y Takei, T Kan, H Takahashi

Journal of Micromechanics and Microengineering  2026

• Access to Document (DOI)

Two-axis transparent force plate for droplet collision measurement using high speed line-scan camera and sampling moiré method

Y Nakahara, T Shiratori, C Lee, YJ Heo, H Takahashi

IEEE Sensors Journal  2026

• Access to Document (DOI)

Simultaneous Measurement of Contractile Force and Ca2+ Concentration Distribution in Human iPS Cell-Derived Cardiomyocytes

Ryota Ikegami, Takuya Tsukagoshi, Kenei Matsudaira, Hidetoshi Takahashi, Thanh-Vinh Nguyen, Kentaro Noda, Ken’ichi Koyanagi, Isao Shimoyama

Sensors  2025.12

• Access to Document (DOI)

Simultaneous Measurement of Contractile Force and Ca2+ Concentration Distribution in Human iPS Cell-Derived Cardiomyocytes

Ikegami R., Tsukagoshi T., Matsudaira K., Takahashi H., Nguyen T.V., Noda K., Koyanagi K., Shimoyama I.

Sensors 25 ( 24 )  2025.12

　View Summary

Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) hold significant promise for regenerative medicine but exhibit immaturity relative to native cardiomyocytes. To make hiPSC-CMs more similar to mature cardiomyocytes, extensive research is being conducted from biochemical, electrochemical, mechanical, and physical perspectives. Quantitatively assessing their maturation is essential to evaluate improvements in cardiac cell function and clarify the impact of previous research. In this study, we present a high-speed sensing system that enables simultaneous, real-time measurement of cardiomyocyte contractile force, and intra- and extra-cellular Ca²⁺ dynamics. To enhance measurement precision, a visualization technique is incorporated to identify individual cardiomyocytes. This simultaneous evaluation system for cardiomyocyte contractility and various ion concentrations has the potential to become an effective and powerful foundational technology for assessing cardiomyocyte maturation and the regenerative medicine applications of IPSC-CMs. The ability to convert cardiomyocyte contractile force into single-cell force implies a more universal evaluation of the mechanical properties.

• Access to Document (DOI)

Laser-Based Fabrication of Piezoresistive Cantilevers Utilizing Pulse Laser Annealing

Nakashima R., Kan T., Takahashi H.

Advanced Sensor Research 4 ( 11 )  2025.11

　View Summary

Microelectromechanical system (MEMS) sensors based on piezoresistive elements are widely used in various applications due to their high sensitivity and compact size. Traditionally, silicon-based MEMS devices have been fabricated using lithography-based processes, with piezoresistive layers formed through thermal diffusion or ion implantation. However, these processes involve complex fabrication workflows. In response, laser fabrication techniques, such as laser micromachining and laser annealing-based impurity diffusion, have attracted attention. In this study, a laser-based approach for fabricating a silicon piezoresistive cantilever using nanosecond-pulse laser annealing is proposed. The proposed process integrates two steps: localized laser annealing for impurity doping and the formation of a partially 3D cantilever structure through laser cutting and etching. All the fabrication steps are performed using a single-laser processing system, enabling direct-write patterning and automatic alignment of the piezoresistive layer with the sensor structure without lithography. In this paper, the effectiveness of the proposed method is evaluated through electrical and mechanical characterizations of the fabricated sensor. The fabricated piezoresistive layer exhibits a gauge factor exceeding 15, indicating that the sensor is sufficiently effective for practical use.

• Access to Document (DOI)

Laser-Induced Graphene Cantilever Airflow Sensor Fabricated via Laser Cutting and Folding a Copper–Polyimide Film

Ohara K., Ando R., Shimada K., Kishimoto T., Nakashima R., Takahashi H.

Advanced Sensor Research 4 ( 10 )  2025.10

　View Summary

Various animals in nature, particularly insects, are equipped with sensory hair capable of detecting minute fluid forces. Inspired by these biological structures, numerous airflow sensors have been developed using Si-based microelectromechanical systems. However, the complexity of the fabrication process and difficulty in integrating shape-controlled sensing elements remain significant challenges. Laser-induced graphene (LIG) has attracted increasing attention as a promising material for various physical sensors, owing to its high piezoresistive sensitivity and simple fabrication process. Polyimide (PI), which is widely used as a substrate for LIG formation, exhibits thermoplastic properties that enable the straightforward creation of 3D structures. This study proposes a single-axis airflow sensor featuring a vertically standing LIG cantilever. The fabrication process involved only a fiber laser for cutting the PI film, forming the LIG-sensing elements, and folding the cantilever structure. The fabricated sensor measured 25 mm × 25 mm at the base and 10.5 mm high. The fabricated sensor integrated surface-mounted circuits within its base. Wind tunnel experiments demonstrate that the sensor exhibits a quadratic response to wind speeds between −10 and 10 m s⁻¹. This approach offers promising prospects for the development of 3D LIG sensing elements for airflow sensors.

• Access to Document (DOI)

Laser-Induced Graphene-Based Pressure Sensor With Corrugated Polyimide Diaphragm

Ryo Oda, Rihachiro Nakashima, Hidetoshi Takahashi

IEEE Sensors Journal  2025.03

• Access to Document (DOI)

Multi-Inlet 2-D Water Flow Vector Sensor Using a Sealed Incompressible Liquid and Neural Network for Marine Biologging

Takuto Kishimoto, Kyota Shimada, Ryusei Ando, Kenei Matsudaira, Hiroto Tanaka, Hidetoshi Takahashi

IEEE Sensors Journal 25 ( 5 ) 8093 - 8105 2025.03

ISSN  1530437X

　View Summary

This study designed and demonstrated a 2-D multiinlet water flow sensor to address challenges associated with measuring the swimming speeds of marine animals owing to size limits and harsh marine environmental conditions, such as clogging by marine debris. The sensor comprises a spherical housing equipped with three pairs of inlets on opposite sides, each connected to a differential pressure sensor element through a tube filled with an incompressible liquid. Notably, a sealed film placed over each inlet prevents marine debris from intruding into the sensor. The differential pressure data collected by the three sensor elements are used to determine 2-D water flow speed and angle using a neural network (NN) trained on water tunnel experiments. The results of the experiments conducted in this study demonstrated that the developed sensor could accurately detect the water flow speed and angle within a speed range of 0.6-2.0 m/s, which is typical of green turtles. The proposed sensor is, therefore, expected to realize improved biologging of marine animal behaviors.

• Access to Document (DOI)

Laser-induced graphene based pressure sensor with corrugated polyimide diaphragm

R Oda, R Nakashima, H Takahashi

IEEE Sensors Journal  2025

Influence of cantilever dimensions on time response characteristics of a MEMS piezoresistive-cantilever-based barometric pressure change sensor

T Kato, H Takahashi

Japanese Journal of Applied Physics 64 ( 5 )  2025

ISSN  00214922

　View Summary

A barometric pressure change sensor utilizing a microelectromechanical system piezoresistive cantilever achieves high sensitivity and robustness. However, its miniaturization is constrained by the trade-off between the cutoff frequency of the mechanical high-pass filter and the air chamber volume. This study investigates the relationship between cantilever dimensions and their frequency characteristics. Experimental and theoretical results confirm that the frequency response varies with cantilever length and thickness. These findings contribute to optimizing these parameters, enabling miniaturization while maintaining high sensitivity and a low cutoff frequency.

• Access to Document (DOI)

Biaxial Glass Force Plate using Inclined Laser Induced Backside Wet Etching through a Prism

N Ono, R Nakashima, T Shiratori, H Takahashi

2025 IEEE 38th International Conference on Micro Electro Mechanical Systems …    833 - 836 2025

ISSN  10846999

　View Summary

This paper reports a biaxial force plate designed to measure ground reaction forces in small insects. The device utilizes a glass spring structure to detect both vertical and shear forces, with two laser displacement meters for force capture. A V-shaped groove formed by fiber laser-induced backside wet etching through a triangular prism, allows precise biaxial force measurements. The proposed force plate structure can be fabricated entirely using laser beam processing. The fabricated force plate realized a force resolution of 0.37 μN, providing the significantly high sensitivity for fruit fly measurement.

• Access to Document (DOI)

Bi-axial micro force plate utilizing dual laser displacement meters for ground reaction force measurement in fruit flies

N Ono, K Shimazaki, H Toda, H Takahashi

IEEE Sensors Journal 25 ( 10 ) 16821 - 16829 2025

ISSN  1530437X

　View Summary

The measurement of ground reaction forces (GRFs) is crucial for evaluating the gait mechanics of small insects, which can contribute to advancements in microrobots. Although a micro force plate capable of multi-axis measurement at the μN scale is desired to fully understand this mechanism, fabrication remains challenging. This study proposes a force plate capable of measuring both vertical and shear forces for a fruit fly, which can be constructed with relative ease. The proposed force plate is fabricated by laser processing, simultaneously producing a plate and its supporting spring structure, which facilitates displacement in the bi-axial directions. The plate displacement is measured using two laser displacement meters inclined at ±45°, directed toward a right isosceles triangular bump located at the plate center. Subsequently, the bi-axial forces are calculated based on Hooke's law. The fabricated force plate realized force resolutions of approximately 0.3μN in both directions, equivalent to 1/30 of a fruit fly's body weight. Finally, GRF measurements during fruit fly walking were successfully demonstrated using the fabricated force plate.

• Access to Document (DOI)

Arrayed Electrical Stimulation Platform for Accurate Evaluation of Contractile Force of Ring-Shaped Engineered Heart Tissue

D Miyata, A Masuda, G Kagawa, H Tani, H Takahashi, S Tohyama, ...

2025 IEEE 38th International Conference on Micro Electro Mechanical Systems …    83 - 86 2025

ISSN  10846999

　View Summary

This paper describes an arrayed culture device for ring-shaped microscale engineered heart tissues (rEHT) to acquire data on the effect of electrical stimulation for contractile force (CF). Elastic pillars in millimeter-scale culture space were fabricated accurately with a 3D printed mold, enabling rEHT formation with small number of cells (1.0×10⁵ cells). Thus, our device is suited to the acquisition of accurate and large numbers of experimental data. Our device was verified by confirming rEHT's response to electrical stimulation and CF measurement from the pillar deflection. We believe that our device would match to explore the electrical stimulus effect for heart tissue maturation with an AI-driven optimization algorithm.

• Access to Document (DOI)

Acoustically Driven Scanning Mirror Enhanced by Helmholtz Resonator Unit

M Fukuta, R Nakashima, T Kan, H Takahashi

2025 IEEE 38th International Conference on Micro Electro Mechanical Systems …    995 - 998 2025

ISSN  10846999

　View Summary

This paper presents a method for amplifying an acoustically driven MEMS scanning mirror by using a Helmholtz resonator (HR). One of the ways for driving MEMS scanning mirrors is the use of acoustic pressure. Here we propose to combine an HR array, whose resonant frequency matches the mirror's mechanical resonant frequency. The HR array is located between the acoustic source element and the mirror. Then, the HR array amplifies sound waves of the target frequency, and the resonance amplifies the mirror vibration. We fabricated a prototype mirror with a piezoresistor, and quantitatively evaluated the vibration amplitude. Experimental results confirmed that the HR amplified the vibration by a factor of approximately 20.

• Access to Document (DOI)

2-Axis Force Plate for Droplet Collision Measurement using Line Scan Camera and Sampling Moiré Method

Y Nakahara, S Kato, H Onoe, C Lee, YJ Heo, H Takahashi

2025 IEEE 38th International Conference on Micro Electro Mechanical Systems …    821 - 824 2025

ISSN  10846999

　View Summary

This paper proposes a method to measure the 2-axis force of a droplet collision when it is dropped on the slope surface. To calculate the 2-axis small impact force at the same time, a force plate using the sampling moiré method with a line scan camera and a prism is employed. The sampling moiré method can precisely calculate the pattern's in-of-plane displacement. Moreover, both in-plane and out-of-plane displacements of the pattern are detectable utilizing a prism. Additionally, a line scan camera can capture 10k images in one second with 4096 pixels width, which is sufficient for high precision and high-time resolution displacement measurement.In this report, line&space patterns are attached to a glass plate, which is supported by four springs. The applied 2-axis force is calculated by multiplying the analyzed displacement and spring constant. We fabricated and calibrated the force plate system. It was confirmed that the force resolutions were less than 4 μN for the 2-axis. Finally, droplet collision experiments were conducted under several conditions. The force plate was able to measure impact force during oblique impact with 2-axis.

• Access to Document (DOI)