Two axis optoelectronic tactile shear stress sensor

Tactile sensors are often used on irregular or moving surfaces, for example as artificial skin on a robotic hand or inside a prosthetic socket. In addition to tactile sensors able to detect pressure, there is also a need to detect shear stress, associated with slippage or friction. Therefore, this paper demonstrates a technology for fabricating unobtrusive flexible tactile shear sensors using a thin and mechanically strong polyimide substrate. The operation of the sensor is based on the changing optical coupling between a Vertical-Cavity Surface-Emitting Laser (VCSEL) and photodiode. Since this sensor is based on an optical principle, it is less susceptible to environmental influences and electromagnetic interference (EMI). Furthermore, a new design of this sensor was developed and tested to enable the detection of both shear force magnitude and direction (two axis sensor).