Structural Solution to Enhance the Sensitivity of a Self-Powered Pressure Sensor for an Artificial Tactile System.

Structural design factors of sensor units have been studied in order to enhance the sensitivity of pressure sensors based on utilizing a piezoelectric material for an artificial tactile sensor. In this study, we have primarily demonstrated the effect of a square pattern array design in a pressure sensor using ZnO nanowires. Nanowires grown on the edge of cells can be bent easily because of growth direction, density control, and buckling effect. Since smaller square pattern arrays induce a higher circumference to cell area ratio, if one sensor unit consists of many micro-level square pattern arrays, the design enhances the piezoelectric efficiency and the sensitivity. As a result, 20 μ m×20 μ m cell arrays showed three times higher pressure sensitivity than 250 μ m×250 μ m cell array structures at a pressure range from 4 kPa to 14 kPa. The induced piezoelectric voltage with the same pressure level also increased drastically. Therefore, the square pattern array design is more appropriate for a high-sensitive pressure sensor than a simple one-body cell design for tactile systems, and it has the advantage of better power efficiency, which is also important for artificial tactile systems. This suggested cell array design can be applied to various systems using piezoelectric nanowires.