A tactile distribution sensor which enables stable measurement under high and dynamic stretch

Recently, we have been studying various tactile distribution sensors based on electrical impedance tomography (EIT) which is a non-invasive technique to measure the resistance distribution of a conductive material only from a boundary, and needs no wiring inside the sensing area. In this paper, we present a newly developed conductive structure which is pressure sensitive but stretch insensitive and is based on the concept of contact resistance between (1)a network of stretchable wave-like conductive yarns with high resistance and (2)a conductive stretchable sheet with low resistance. Based on this newly developed structure, we have realized a novel tactile distribution sensor which enables stable measurement under dynamic and large stretch from various directions. Stable measurement of pressure distribution under dynamic and complex deformation cases such as pinching and pushing on a balloon surface are demonstrated. The sensor has been originally designed for implementation over interactive robots with soft and highly deformable bodies, but can also be used as novel user interface devices, or ordinary pressure distribution sensors. Some of the most remarkable specifications of the developed tactile sensor are high stretchability up to 140% and toughness under adverse load conditions. The sensor also has a realistic potential of becoming as thin and stretchable as stocking fabric. A goal of this research is to combine this thin sensor with stretch distribution sensors so that richer and more sophisticated tactile interactions can be realized.

1 Introduction

An ideal tactile sensor should be thin, high-resolution, soft and stretchable. Most conventional tactile sensors have been fabricated over thin film-type substrates, and use matrix-based wiring technique which can handle elements only using wires. Film-type tactile sensors can be thin, have high resolutions and can be bent to adapt over mildly curved cylindrical surfaces.