Fabrication and characterization of pneumatic capacitive-dielectric sensor

Two inflatable-types of dielectric sensor (one sided-inflatable (OIDS) and two sided-inflatable (TIDS)) were fabricated using acrylic rubber coated with a compliant electrode. The effect of air-pressure (P) on capacitance (C), coated area of compliant electrode, vertical deformation (R _inf ) and the volume change were studied. An increase in P expanded the volume, area of coated electrode and R _inf respectively. In terms of R _inf , OIDS and TIDS were stretched above 500 and 800% while swollen to values higher than 23,000 and 77,000% respectively, in terms of volume expansion. These expansions caused changes in the output C for sensors, due to changes in polarization. The measured normalized sensitivity coefficients (nGF), a fractional change in pressure (ΔP/P _o ) versus area strain (ΔA/A _o ) was ∼20.73 and ∼13.6 for OIDS and TIDS respectively. TIDS reached 1.1 kPa ^-1 at 0.4-0.68 kPa while OIDS recorded 0.12 kPa ^-1 at 0.4-1.1kPa pressure, in terms of sensitivity (S) based on flexible capacitive sensors ((ΔC/C _o )/(ΔP)). The OID harvested an electrical energy of ∼208μJ/s at area expansion ∼186% and could theoretically be used to harvest ∼18J in a day. Therefore, the sensors show promising multifunctional characteristics suitable for applications including; detection of pressures from natural disasters windstorm/typhoon and for harvesting energy.