Dome-shaped tactile sensor for detecting object stiffness and potential

Multi-functional tactile sensors, capable of measuring multi-physical quantities in a limited space by one structure, have aroused great research interest. This paper proposes a monostable dome-shaped sensor for the simultaneous measurement of the stiffness and surface potential of the object at the same position. In the proposed sensor, the top electrode is a flexible spherical stainless steel dome, and the bottom electrode is a circular sheet covered with an electret film, providing a bias electric field. Output Voltages between two electrodes are generated because of the electrostatic effect, and resulting waveforms can be measured as the proposed sensor contacts and releases the object. While the proposed sensor approaches the object, the surface potential of the object determines the voltage waveform. After contacting the object, the voltage waveform indicates a direct comparison of stiffness between the object and top electrode, based on the monostable buckling of the dome. Here, we present theoretical and experimental relationships between measured voltages obtained from the proposed sensor and a charged electret film on the surface of the object. The proposed sensor makes it possible to measure the stiffness and surface potential of the object using voltage waveforms.