Fabrication and Characterization of Pneumatic Capacitive-Dielectric Sensor

AbstractTwo inflatable-types of dielectric sensor (DeS) were fabricated using acrylic rubber coated with compliant electrode. The first is a one sided-inflatable sensor (OIDS) while the other is two sided-inflatable sensors (TIDS). The effect of air-pressure (P) supply on the capacitance (C) was measured with the help of a multimeter. Other several parameters such as the coated diameter of compliant electrode, vertical deformation (Rinf), area of coated electrode and volume of expansion etc. were carefully examined in response to the air-pressure and the results were compared. It was observed that an increase in the air-pressure supply increased the volume, area of coated compliant electrode and the Rinf. For instance, in terms of Rinf, the OIDS and TIDS stretched to over 500 and 800% while in terms of volume strain the OIDS and TIDS swelled to values above 23,000 and 77,000% respectively. These expansions caused an increase in the output capacitance for the OIDS but decayed exponentially for the TIDS, suspected to be a decline in polarization. The gauge factor (GF), a measure of sensitivity of strain gauges and sensitivity (S) based on flexible capacitive sensors (∆C/Co/Pressure (∆P)) were employed to model the various parameters. The OIDS dominated in most of the GF determined. For instance, the OIDS recorded a GF~20.73 when strained biaxial with respect to air-pressure but TIDS recorded GF~13.6. In terms of the S performance, the TIDS reached 1.1kPa-1 at 0.4-1.1kPa while the highest S recorded by OID was 0.12kPa-1 at 0.4-0.68kPa. Therefore, sensors of this kind could be used in many areas including; detection of air-pressures from natural disasters like tornadoes, blizzards, checking human breath, soft robotics, tactile sensors and for harvesting energy.