Development of Wearable Sheet-Type Shear Force Sensor and Measurement System that is Insusceptible to Temperature and Pressure.

Shigeru Toyama,Takuma Okamoto,Yasuhiro Tanaka,Ryo Uehara,Takashi Nakamura,Tokio Umino,Hiroshi Igarashi,Satoshi Shirogane

doi:10.3390/s17081752

Abstract

A sheet-type shear force sensor and a measurement system for the sensor were developed. The sensor has an original structure where a liquid electrolyte is filled in a space composed of two electrode-patterned polymer films and an elastic rubber ring. When a shear force is applied on the surface of the sensor, the two electrode-patterned films mutually move so that the distance between the internal electrodes of the sensor changes, resulting in current increase or decrease between the electrodes. Therefore, the shear force can be calculated by monitoring the current between the electrodes. Moreover, it is possible to measure two-dimensional shear force given that the sensor has multiple electrodes. The diameter and thickness of the sensor head were 10 mm and 0.7 mm, respectively. Additionally, we also developed a measurement system that drives the sensor, corrects the baseline of the raw sensor output, displays data, and stores data as a computer file. Though the raw sensor output was considerably affected by the surrounding temperature, the influence of temperature was drastically decreased by introducing a simple arithmetical calculation. Moreover, the influence of pressure simultaneously decreased after the same calculation process. A demonstrative measurement using the sensor revealed the practical usefulness for on-site monitoring.

Highlights

Thin wearable shear force sensors have been desired in the field of rehabilitation engineering.One example is a sensor used to measure the shear force between the prosthetic limb and stump of lower limb amputee patients
The major major factor factor of of electrolyte electrolyte conductivity conductivity is is electrolyte attributed to ion mobility, which is directly related to the liquid viscosity
It is known that liquid attributed to ion mobility, which is directly related to the liquid viscosity

Summary

Introduction

Thin wearable shear force sensors have been desired in the field of rehabilitation engineering. One example is a sensor used to measure the shear force between the prosthetic limb and stump of lower limb amputee patients. The compatibility of prosthetic limbs with stumps currently depends on the intuition and experience of the prosthetist and the feeling of the user’s fit. Sanders et al [1] incorporated a force sensor in a prosthetic limb; the sensor was bulky and was installed with a hole in the prosthetic foot. This method proved interesting as a piece of research, it cannot be applied to prosthetic limbs used by patients

Methods

Discussion

Conclusion