Parylene-C Embedded CNT-Based MEMS Piezoresistive Pressure Sensors Using DEP Nanoassembly

This paper reports the characterization of a novel MEMS sensor using Carbon nanotubes (CNTs) as sensing elements. Using a MEMS-compatible process and the dielectrophoretic (DEP) nanoassembly of CNTs, we have successfully integrated bundled strands of CNT sensing elements on arrays of Polymethylmethacrylate (PMMA) diaphragms. With a thin film of Parylene-C to enhance the CNT to electrode contact, the CNT bundles show consistent and repeatable piezoresistivity from multiple electromechanical measurements. Using low noise data acquisition techniques and annealing treatments of the CNTs, the fluctuations of the sensor signal are greatly reduced. Based on these experimental evidences, we propose that embedded in Parylene-C thin film, CNT-bundles is a novel material for fabricating micro pressure sensors on polymer substrates-which may serve as ultra-low-power (μW) and low-noise sensors when bio-compatibility and low-cost applications are required.