CMOS Chip for Solid-State Tactile Force Sensor

This study presents a simple approach to design and implement a solid-state micro tactile force sensor using the standard CMOS process (Fig. 1). By using the inductive sensing mechanism with the magnetic force contact interface and the CMOS on-chip analog circuit, the normal force is detected by the inductance change of the sensing coil and readout by characterizing the frequency variation of the LC tank oscillator. The proposed micro tactile force sensor has two major merits: (1) the fabrication process of the proposed tactile sensor is straightforward, and the fragile suspended structure is not required to detect the tactile load. Therefore, the process issues and the design concerns of the unwanted deformation induced by the residual stress of the CMOS thin films can be avoided. (2) Taking the advantages of the standard CMOS process (TSMC 1P6M CMOS process), the sensing component and the processing circuitry are monolithically integrated for direct signal processing with a better signal-to-noise ratio (SNR). The measurement results verify the feasibility and functionality of the proposed micro tactile sensor. For future perspectives, the proposed device can be exploited to the applications required compact tactile force sensing system. Moreover, more processing circuit components can be incorporated monolithically to provide more versatilities.