A proposal of new layer sensor based on PVDF film for material identification

This paper proposes a new layer sensor for material identification under the visible light. In the proposed sensor, the optical sensor and PVDF (polyvinylidene fluoride) film with the transparent conductive electrodes are layered. The optical properties of the material are measured by a light emitting diode (LED) and a phototransistor, and the electrical properties are measured by a pair of the transparent conductive electrodes of PVDF films arranged on the surfaces of the LED and phototransistor. In addition, the vibrational property is obtained by PVDF film. Therefore, the optical, electrical and vibrational properties of the material are measured by the proposed layer sensor. To test the sensor experimentally, eleven material samples – clear, white, blue, green and black acrylic, clear glass, white polytetrafluoroethylene, silver aluminum and sponge with three types of hardness – were prepared. In the contactless measurement under the visible light, the identification of their sample materials and the detection of distance between the sensor and the surface of material were demonstrated by using the measurement values of the optical and electrical properties in the proposed sensor. In addition, the hardness was detected by the vibrational property at the contact between the proposed sensor and the material. The results indicated the usefulness of the proposed layer sensor as the proximity and touch sensors for the material identification such as optical, electrical and hardness properties, although there are still some problems that must be addressed.