The scratch drive operates as follows. When a voltage is applied between the silicon plate and the substrate beneath it, the plate is drawn down into contact with the substrate. Since the front of the plate is supported by the bushing, strain energy is stored in the plate, and the edge of the bushing is pushed forwards. When the voltage is removed, the strain is released and the scratch drive plate moves forwards.
When an AC signal is applied, the above cycle is continuously repeated, and the scratch drive moves forward in a step-wise manner. Scratch drives have been operated at frequencies as low as 10 Hz, and as high as 2 kHz, with voltages ranging from 30 - 200 V.