A multifunctional integrated silicon tactile imager with arrays of strain and temperature sensors on single crystal silicon diaphragm

In this study, a silicon multifunctional tactile imager with the simultaneous detection abilities of ‘3D surface shape’ and ‘temperature distribution’ of touching object has been realized with silicon LSI/MEMS technology. The pixel circuit array including a piezoresistor and a temperature sensor is integrated on elastic surface of pneumatically swollen silicon diaphragm. Also, elasticity detection of touching object has been simultaneously realized with signal processing in frequency domain. Prototype tactile imagers with a 3.1 mm × 3.1 mm sensor diaphragm integrating 420-μm pitch multifunctional sensor pixel array have been fabricated. In the evaluation experiments, the shape of a 1.5 mmϕ soft tube was successfully detected. Also, simultaneous measurement of surface shape and temperature distribution was performed using a heated metal pipe. The detectable lower-limit of vibration in this tactile imager was below 1.0 μm with signal bandwidth more than 2 kHz. Using the ability of vibration detection, the three kinds of materials with different elasticity (0.59–7.04 mN/μm) were successfully distinguished with the tactile imager. The highly sensitive and multifunctional tactile imager with versatile detection ability has been realized by sophisticated integration ability of silicon-MEMS technology.