Surface shape capture with boundary electrodes

A system is proposed for monitoring changes in surface shape that is portable, inexpensive, durable, and works in many places where traditional shape monitoring techniques would fail. This system is ideally suited to monitoring large-scale surface deformations on surfaces like cloth without excessive wiring or the need for special purpose equipment. It is composed of a semiconductor-insulator-semiconductor sandwich of carbon-loaded polymer and unloaded polymer with electrodes attached at the boundary. The electrical properties of the material are sampled by applying currents and measuring resulting voltages at the boundary electrodes. The piezoresistive and geometry changes of the semiconductor layers results in resistance variations across the surface according to local curvature. Through sufficient sampling, a system of equations can be solved for the interior curvature properties. The local curvature data is integrated to yield an approximation of the surface shape. Various results are given that demonstrate the feasibility of the sensor with a prototype device.