Inkjet printing has become a promising way to fabricate electrical mechanical devices and it has become a tool for rapid manufacturing technology. In this paper, the fabrication procedure and the characterization of the piezoresistive properties of Carbon nanotube (CNT) - Polyimide (PI) nanocomposites are presented. The suspensions of CNT-PI nanocomposites of five different CNT weight concentration based on the percolation threshold were fabricated, and the suspensions were then deposited on the polyimide substrate by a drop-on-demand piezoelectric inkjet printer. This makes it possible for the uniformity and geometry of the thin film to be highly controlled. Once the nanocomposites were fully cured, the strain sensors were ready for calibration. Under uniaxial tension, the strain and resistance change of the strain sensors were measured, and the gauge factors could be calculated. The temperature and humidity are two potential factors to effect the performance of the strain sensors. The temperature coefficients of the CNT-PI nanocomposites were measured and the temperature compensation methods were proposed. The humidity effect on the nanocomposites was also monitored, and a thin layer of Parylene-C was coated on the surface of the nanocomposites thin film and the effect of the coating was tested. In general, the inkjet printing technique was proved to be a convenient way to fabricate flexible nanocomposites thin film with uniform thickness and precise geometry control. The CNT-PI nanocomposite has good performance as piezoresistive strain sensor.
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