In this study, a parasitic capacitance-free tactile sensor with a floating electrode that is capable of identifying actual physical contact pressure by distinguishing from parasitic effects and applicable to sensor arrays is presented. Although capacitive pressure sensors are known for their excellent pressure sensing capabilities in wide range with high sensitivity, they tend to suffer from a parasitic capacitance noise and unwanted proximity effects. Electromagnetic interference shielding was conventionally used to prevent this noise; however, it was not entirely successful in multicell array sensors. Parasitic capacitance-free method involves the use of a floating electrode, which functions as a contact trigger by causing sudden changes in capacitance only when the actual physical contact pressure has been applied or removed. The proposed method is robust, consistent, and precise. Experimental results show a wide range of pressure response up to 2.4 MPa with a sensitivity of 0.179 MPa-1 (up to 0.74 MPa) and negligible hysteresis.
Keywords: flexible sensor; parasitic capacitance free; pressure sensor; proximity; tactile sensor; wearable.