In medical devices for precision controlled drug delivery, such as infusion pumps, insulin pumps or nebulizers, piezoelectric micropumps offer an attractive alternative to standard pumps. Piezoelectric micropumps are small, lightweight, low power, low cost, and accurate.
This application note describes the implementation of a basic driver circuit for driving a piezoelectric micropump with flow control in an example of fluid delivery. The described system includes a control board, a high voltage driver board, and an mp6 Piezoelectric Diaphragm Micropump.
A Piezoelectric micropump is a miniaturized mechanical pumping device employing a piezoelectric actuator in combination with passive check valves. When voltage is applied, a piezoelectric actuator expands or contracts, which causes the liquid or gas to be sucked into or expelled from the pump chamber. The check valves on both sides of the pump chamber govern the flow in one direction.
One of the challenges in designing a piezoelectric micropump driver is the requirement for high supply voltage to be applied to the piezoelectric actuator. The following sections demonstrate how to use the Core Independent Peripherals (CIPs) and the intelligent analog peripherals featured in Microchip's 8-bit microcontrollers, along with Microchip's high voltage device family to generate reliable high voltage signals at a specific frequency for driving a piezoelectric diaphragm micropump.