Slippage and direction sensing based on a flexible tactile sensor with structural electrodes

A novel flexible tactile sensor for sensing the incident slippage and its direction were designed by introducing the concept of structural electrodes on a piezoelectric film (PVDF). The structural electrodes consisted of an elastomeric column on the top of PVDF film with the distributed microelectrodes underneath the elastomeric column. As an object was placed upon the elastomeric column and pushed by an external force, the occurrence of slippage can be detected by the output voltages from the distributed microelectrodes due to the corresponding bending stresses distributed on the PVDF film. In addition, two opposite output voltages read out from different microelectrodes can differentiate the direction of slippage while the elastomeric column was bent by the friction force between the object and column surface. As the experimental results, two peak voltages happened simultaneously in either compressive-stress area or tensile-stress area when the slippage occurred. Thus, the slippage between the object and elastomeric column can be detected. Besides, the peak value of slippage voltage depends on the height of column and the weight of object. This paper successfully demonstrated the concept of structural electrodes for sensing the incident slippage based on a piezoelectric tactile sensor.