Space Charge Characteristics of Slide-ring Materials under Various Voltage Applications

Dielectric elastomers have potential for devices such as a pressure sensor or an actuator for an artificial muscle. To understand the electrical properties, the space charges in slide-ring materials (SRMs) are measured using the pulsed electro acoustic (PEA) method under various applied voltage applications. The positive space charge in the bulk is dominated under a dc constant voltage application, and the positive charge amount increases with the voltage application time. However, as the applied voltage increases, the positive charge amount decreases with the voltage application time. A negative charge injection by the hetero space charge effect due to the local field enhancement by the positive charge near the cathode occurs. The positive space charge in the SRM is observed under a voltage of +3 kV in the square wave voltage of +3 kV/0 kV. When the magnitude of the negative voltage in the square wave voltage increases, the space charge is not observed. Hence, negative charge injection may neutralize the positive space charge or the positive space charge may be swept out when a negative voltage is applied.