Piezoresistive Tactile Sensor Discriminating Multidirectional Forces.

Youngdo Jung,Hyunhyub Ko,Hyuneui Lim,Duck-Gyu Lee,Jonghwa Park

doi:10.3390/s151025463

Abstract

Flexible tactile sensors capable of detecting the magnitude and direction of the applied force together are of great interest for application in human-interactive robots, prosthetics, and bionic arms/feet. Human skin contains excellent tactile sensing elements, mechanoreceptors, which detect their assigned tactile stimuli and transduce them into electrical signals. The transduced signals are transmitted through separated nerve fibers to the central nerve system without complicated signal processing. Inspired by the function and organization of human skin, we present a piezoresistive type tactile sensor capable of discriminating the direction and magnitude of stimulations without further signal processing. Our tactile sensor is based on a flexible core and four sidewall structures of elastomer, where highly sensitive interlocking piezoresistive type sensing elements are embedded. We demonstrate the discriminating normal pressure and shear force simultaneously without interference between the applied forces. The developed sensor can detect down to 128 Pa in normal pressure and 0.08 N in shear force, respectively. The developed sensor can be applied in the prosthetic arms requiring the restoration of tactile sensation to discriminate the feeling of normal and shear force like human skin.

Highlights

The skin is the largest sensing organ that humans have and versatile in detecting tactile stimulations.While typical touch sensors installed on the screen panels of mobile devices are only dense arrays of sensitive on-off switches, human skin consists of mechanoreceptors that can discriminate the magnitude and type of external touch inputs as well as provide critical information in recognizing contacted objects and manipulating hands, feet, and other parts of human body safely.As the demands for robots working in human-interactive way and the prosthetic arms or legs for patients have increased, there have been great interests in the development of tactile sensors capable of measuring external stimulations as human skin does
Unlike human skin equipped with distinct types of very sensitive mechanoreceptors responsible for their assigned tactile stimulations and the transduced tactile information conveyed along to central nerve system [31], most multi-axis tactile sensors were based on mapping or complicated post signal processing of sensing data from multiple sensing elements in discriminating the force direction and magnitude
We present a piezoresistive type tactile sensor capable of discriminating the direction and magnitude of tactile stimulations without further signal processing

Summary

Introduction

The skin is the largest sensing organ that humans have and versatile in detecting tactile stimulations. Enhanced sensitivities have been demonstrated in a capacitive tactile sensor with the microstructured rubber dielectric layers [6], resistive pressure sensors based on elastic hollow-sphere microstructured conducting polymer [18] or interlocking microstructures [19,20], and a piezoelectric pressure sensor with microstructured elastomer layer [11] New fabrication methods such as contact printing or transfer printing enabled the development of ultra-thin and ultra–lightweight flexible tactile sensors [21,22,23,24,25]. Unlike human skin equipped with distinct types of very sensitive mechanoreceptors responsible for their assigned tactile stimulations and the transduced tactile information conveyed along to central nerve system [31], most multi-axis tactile sensors were based on mapping or complicated post signal processing of sensing data from multiple sensing elements in discriminating the force direction and magnitude. With a flexible core and four sidewall structures of elastomer having embedded highly sensitive interlocking piezoresistive type sensing elements, the newly designed piezoresistive tactile sensors discriminated the magnitude and direction of the applied force successfully without complex post signal processing even under gentle touch

Working Principle

Fabrication

Experimental Results

Conclusions