Abstract

This paper suggests a high resolution, high frame rate strain mapping sensor that uses three layers to measure the position as well as the value of the strain applied at different locations of the sensor. The top layer which should be highly conductive can be connected to either a current source or a voltage source, depending on the value of conductivity separating it from the ground during the switching sequence. The middle layer which consists of a strain-compressible material, such as piezoresistive foam, exhibits a variable electric resistance the value of which decreases with the increase of the applied strain. In this paper, the sensor sensitivity ranges from 50 to 500 kPa, however it can accommodate any other type of piezoresistive material provided that an adequate calibration is done. The lower layer consists of segmented highly electrically conductive tracks, the pattern of which allows to detect both the location, and the strain intensity at the points of contacts. The sensor is designed to also compensate for eventual changes of the electric resistance function of the temperature. Additionally, it has the advantage to mitigate eventual crosstalks that may occur between adjacent electrodes, since it keeps grounding utmost two electrode, forcing the electric current to flow into only two points. To our best knowledge, these simultaneous attributes have not been reported by a single system. This yields the advantage of using the sensor for a wide range of applications, including rehabilitation and human-computer interaction. A series of experiments and FEM simulations reveal that the sensor is highly accurate and can provide both the location and intensity of multiple contacts with an accuracy of 97.5 % at a frame rate of 20 frames/s when using 29 electrodes.