Transparent force sensing arrays with low power consumption using liquid crystal arrays

Abstract

A transparent force sensing array with low power consumption is developed from a 3×3 liquid crystal (LC) array. As force is applied to the LC array, the force-dependent capacitance curve of a sensor pixel under a higher voltage will shift to larger capacitance. Accordingly, the force range of the LC array can be divided into many sub-ranges at one of the capacitance values. The number of the input voltage is equal to that of the output capacitance in each of the sub-ranges, and the voltage-to-capacitance number is small (large) in the high (low)-force sub-range. The sensing array measures force in terms of the voltage-to-capacitance number. The transparent force sensing array shows potential as a touch panel, while it is immune to the need of rectifying the nonlinear relation between the applied force and the output capacitance using complex algorithm via high-end microcontrollers.