An Array System of Proximity and Tactile Sensors by Simultaneous Measurement of Optical and Electrical Properties

We developed a single unit proximity and tactile sensing method that simultaneously uses optical and electrical measurements. The proposed sensor consists of a pair of electrodes and a photodiode with a light emitting diode (LED). An increase in the electrode size is required in order to increase the sensitivity of electrical measurements. In addition, a smaller separation between the photodiodes is needed for high spatial resolution by optical measurement. In this paper, we proposed a structure that consists of a pair of electrodes and four pairs of photodiodes with LEDs for an array system. In the experiment, the identification of materials (grounded conductor or other materials), and detection of indentations on the sensor surface were demonstrated by a single sensor in contact and non-contact (proximity range). Furthermore, the prototype sensor array (3 × 3 units) measured the shape of the object. The proposed sensor may be useful as a tactile and proximity sensor for robots.