Texture Characterization Including Warm/Cool Sensation using Force-, Light-, and Temperature-Sensitive Microelectromechanical Systems Sensor

Abstract

In this paper, we report on texture measurements for an object, including tactile, warm/cool, and light sensations using a multimodal micro-electromechanical systems (MEMS) sensor. This MEMS sensor can detect force as a resistance change of the strain gauge on a microcantilever and light as an impedance change of a Si layer by a photoconductive effect. The sensor, which was maintained near human body temperature using a heater, can also detect a temperature drop after heat transfer from the sensor to a contacted object as a resistance change of the strain gauge or an impedance change of the Si layer. In this work, three different materials (copper, acrylic, and wood) were chosen as the target objects for the measurement of surface texture, and they were characterized on the basis of the differences in sensor outputs in active sensing experiments (approaching and pressing of the sensor with a probe light) on the sensor surface. In the proximity process, the impedance change of the Si layer depends on the surface reflectivity of the objects. After the object is touched by the sensor surface, the impedance of the Si layer and the resistance of the strain gauge of the sensor increase with the change in temperature caused by heat transfer. Furthermore, the resistance of the strain gauge decreases with the deformation of the cantilever caused by the pressing force from each object. Therefore, it is demonstrated that surface texture including the mechanical, optical, and thermal characteristics of various materials can be evaluated by active sensing using the proposed MEMS multimodal sensor.