A Miniature Multiaxis Force/Torque Sensor for Acupuncture

Abstract

To realize the quantitative analysis and research of traditional Chinese medicine (TCM) acupuncture manipulations, miniaturized multidimensional force sensors are necessary to measure the lifting–thrusting force and twisting torque in the process of acupuncture, which records the manipulations of excellent physicians for relevant physicians to learn and improve their manipulations. A miniature multiaxis force/torque ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${F}/{T}$ </tex-math></inline-formula> ) sensor for acupuncture is developed in this article. The elastomer of the design adopts hollow thin-wall cross beam structure with inverted <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T}$ </tex-math></inline-formula> floating beam, which retains the space for the strain gauge to be pasted, reduces the coupling between dimensions, and improves the sensitivity and accuracy. This design has the advantages of miniaturization, lightweight, high precision, and convenient needle substitution. The elastomer is processed with polyetheretherketone (PEEK) material to reduce the mass. First, the feasibility of the hollow thin-wall cross beam structure with inverted <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T}$ </tex-math></inline-formula> floating beam is verified by ANSYS finite element simulation. Then, the hardware system based on STM32 is designed to realize signal acquisition, amplification, and transmission. Next, the static calibration and decoupling of the sensor are accomplished with the calibration device. The calibration results indicate that the accuracy of the sensor is high (the coupling error is less than 2%). Finally, the acupuncture force measurement system is constructed to complete the acupuncture manipulation experiment. The experimental results demonstrate that our system can accurately obtain the needle force information and can distinguish different acupuncture manipulations, which verifies the feasibility of the sensor while realizing the quantitative characterization of acupuncture manipulations.