A fluid pump, such as a print head, includes an ink channel having a nozzle and at least one wall having a flexible portion. A deforming member made of a viscoelastic material is coupled to the flexible portion and a charge mechanism is coupled to the deforming member to apply a spatially varied charge...http://www.google.com.au/patents/US6428146?utm_source=gb-gplus-sharePatent US6428146 - Fluid pump, ink jet print head utilizing the same, and method of pumping fluid
