A User-Friendly Packaging Solution for Silicon-Based Pressure Die to Develop Prosthetic Tactile Sensing

At present, most of tactile sensors integrated in prosthetic hands are installed on the surface of the fingers, which destroys the curved and compliant nature of finger surface that is important for the manipulation of objects. To solve this problem, this paper proposes a user-friendly packaging solution with solid-liquid hybrid structure for silicon-based pressure die to develop a force sensitive artificial finger which can meet the requirements of sensor sensitivity while maintaining the geometric and mechanical features of the finger surface. The artificial finger consists of a packaging including a thumb-shaped finger stall and a certain amount of dielectric liquid, a rigid phalange, a silicon-based pressure die, a printed circuit board (PCB), and a clamp plate. When a force is applied on the pad of the artificial finger, the finger stall deforms, which compresses the liquid in the chamber and result in a resistance change of the pressure die. A prototype with the overall size of 37 mm $\times32$ mm $\times50$ mm was developed and tested. Results showed that the artificial finger has good sensing performance with force detection range of 5.7 mN to 10.5 N, sensitivity of 3.34 mV/N and 1.99 mV/N in the range of 0 - 4.0 N and 4.0 N - 10.5 N respectively, linearity of 0.99, repeatability error of 0.77%, and hysteresis error of 2.9%. Furthermore, two typical daily applications including the mouse click and the texture recognition were carried out with the prototype, proving good real-time detecting capacity and dynamic characteristic.