A capacitive pressure sensor with a nano-needle dielectric was successfully fabricated by a facile breath figures method and demonstrated a record sensitivity among polymer tactile sensors. The choice of dielectric microstructure is important, and the dielectric with a nano-needle showed sensitivity up to 1.76 kPa-1. This high sensitivity is due to the sharpness of nano-needles with radius of curvature around 10 nm. The capacitor with the nano-needle filler was integrated with an inkjet printed OTFT, and it showed high pressure response in agreement with capacitance change. This showed that the current of OTFTs increased with pressure due to an increase in capacitance, which in turn enhanced charge accumulation in the conduction channel. Structural advantage of the nano-needle film facilitated very high sensitivity for the capacitive pressure sensors. These pressure sensors integrated with printable OTFTs will be enabling for many flexible, large-area pressure sensing applications.
Kim, J.; Ng, T.; Kim , W. Highly sensitive tactile sensors integrated with organic transistors. Applied Physics Letters. 2012; 101 (10): 103308.