Tactile sensor using piezoelectric resonator

A new type of tactile sensor probe head which detects compliance of live tissue has been developed. The sensor consists of a Colpitts circuit including a 1.5 mm×1.5 mm piezoelectric resonator on a mount 2.4 mm in diameter. This size is small enough to be inserted into the human body. Experimental results show that the oscillating frequency change versus the contact force is related to the object compliance. Especially, the maximum gradient of the oscillating frequency versus contact force curve is able to identify the difference of the compliance. It is possible to measure accurate compliance without setting the contact force constant