Porous CNT/rubber composite for resistive pressure sensor

In this study, a simple and effective method is developed to prepare porous conductive nanocomposite with great stability for pressure sensing applications. Fluorine rubber and single wall carbon nanotube (SWCNT) were mixed together to produce a pressure-sensitive rubber (PSR). The conductive filler, SWCNT, can result in better composite homogeneity during the manufacturing process of conductive PSR. We choose SWCNT because of its high aspect ratio, better conductivity and nearly ohmic property; therefore, better pressure/resistance sensitivity can be achieved. This conductive PSR showed resistance variation to compressive stresses and can be used to measure applied pressures with a sensitivity of 0.35 MPa−1. To enhance the sensitivity, foaming agent (N, N'-Dinitrosopentamethylenetetramine, DPT) was mixed with the PSR to create porous structures with controllable pore size (0.43–1.8 mm) by changing the foaming agent content. The porous PSR had a better deformability and thus the sensitivity increased to 4.31 MPa−1. The porous PSR exhibits response and recovery times about 0.25 s and 0.15 s, respectively. Great shape recovery and measurement stability of the porous PSR is also observed after more than 1000 compression/release cycles. The porous PSR can be easily assembled with printed circuits to provide quick and accurate measurements. Several examples, such as punch-force measurement on a boxing game glove and plantar pressure distributions, were also demonstrated to show the capability of the porous PSR for dynamic response monitoring applications.