A flexible ionic liquid-polyurethane sponge capacitive pressure sensor

Abstract A flexible microfluidic polyurethane sponge super-capacitive pressure sensor is developed to measure the pressure. The innovative sensor contains a polyurethane sponge filled with ionic liquid dielectric layer, and coated with two indium tin oxide polyethylene terephthalate (ITO-PET) films on the top and bottom, respectively. When external pressure is applied on the sensor, the contact area between ITO-PET electrode and ionic liquid polyurethane sponge (ILPU) dielectric layer increases and the distance between two ITO-PET electrodes decreases due to the structural deformation, resulting in the capacitance of the sensor increasing rapidly. The external pressure will be determined based on the change of capacitance. Comparing to traditional pressure sensor, the developed sensor provides a high sensitivity up to 5.28 nF/KPa and rapid dynamic responses for pressure measurement. Experiments are also conducted to investigate the influence of the temperature and humidity.