Polysilicon Piezoresistive Tactile Sensor Array Fabricated by PolyMUMPs Process

This paper discusses the design, fabrication and testing of a 5x5 micromachined tactile sensor array for the detection of an extremely small force (micrometer-Newton range). Central contacting pads that are trampoline-shape suspended structures and sensor beams are formed using an anisotropic etching of silicon substrate of a MUMPs process chip. A piezoresistive layer of polysilicon embedded in sensor beams is used to detect the displacement of the suspended contacting pad. Each square tactile has dimension of 200 mum x 200 mum with 250 mum center-to-center spacing. The entire sensor area is 1.25 mm x 1.25 mm. The device was characterized under various normal force loads using weight microneedles. The individual sensor element shows the linear response to normal force with good repeatability.