Piezoresistive pressure sensors with parallel integration of individual single-walled carbon nanotubes

Abstract

A major obstacle in the realization of commercially viable single-walled carbon nanotube (SWNT) devices, hindering the functionality of this uniquely interesting type of material, is their type and site selective integration. Specifically, SWNT based piezoresistive pressure sensors require the incorporation of individual small bandgap semiconducting (SGS-)SWNTs at the positions of highest membrane strain. In this paper, the purely parallel fabrication of ultrasmall piezoresistive pressure sensors (membrane diameter 100–120 μm) with SGS-SWNTs as active transducer elements is demonstrated, using dielectrophoresis. Good alignment avoids strain components other than from the principal axis and superior strain sensitivity to state-of-the-art silicon based piezoresistive pressure sensors is achieved through the highly selective integration of SGS-SWNTs at high dielectrophoretic deposition frequencies. The long-term stable devices have sensitivities as high as S0 ∼0.25 ΔR R−1 bar−1, at a resolution better than 50 mbar, and a power consumption of less than 40 nW. The scale-up of the introduced robust and reliable fabrication process is straight-forward and provides very promising avenues toward successful realization of functional, commercially viable SWNT sensors.