Development of polyimide flexible tactile sensor skin

We present the development of a polyimide-based two-dimensional tactile sensing array realized using a novel inverted fabrication technique. Thermal silicon oxide or Pyrex® substrates are treated such that their surfaces are OH group terminated, allowing good adhesion between such substrates and a spun-on polyimide film during processing through what are suspected to be hydrogen bonds that can be selectively broken when release is desired. The release of the continuous polyimide film is rapidly accomplished by breaking these bonds. This process results in robust, low-cost and continuous polymer-film devices. The developed sensor skin contains an array of membrane-based tactile sensors (taxels). Micromachined thin-film metal strain gauges are positioned on the edges of polyimide membranes. The change in resistance from each strain gauge resulting from normal forces applied to tactile bumps on the top of the membranes is used to image force distribution. Response of an individual taxel is characterized. The effective gauge factor of the taxels is found to be approximately 1.3. Sensor array output is experimentally obtained. The demonstrated devices are robust enough for direct contact with humans, everyday objects and contaminants without undue care.