A 25 mm2 smart pump developed at the Fraunhofer Research Institution for Microsystems and Solid State Technologies EMFT in Munich, Germany, might be viewed as the world’s smallest but it still has a high compression ratio. The device was designed to deliver air to smartphone-integrated gas sensors for ambient air analysis.
The micro diaphragm pump uses the piezoelectric effect to convert an applied electrical field into mechanical strain and generate pressure in the pump chamber. Alternating the voltage helps move a silicon membrane up or down, which in turn draws in ambient air through a valve and compresses it in the pump chamber before it is expelled.
Pump suction capacity gets a boost by using the piezo effect to preload the diaphragm when assembling the piezoceramic. The design eliminates the need for a deep pump chamber while allowing for device miniaturization.
Monocrystalline silicon is also used to fabricate the flap valves and pump chambers, as this material offers improved pliability and durability relative to metals and plastics. Pump components can be etched from the silicon layer with a high degree of precision and subsequently joined together.
The smart pump is designed to deliver air specifically to the gas sensors, which would reduce the current reaction time from several minutes to just two seconds. The system could measure not only the concentration of particulate matter but also, for instance, whether the air in a room is stale and a window should be opened for ventilation.
The micropump could also be used as a medical patch to continuously deliver tiny amounts of hormone or pain killer, or as an implant to help regulate pressure within the eye in treating glaucoma. The pump could also supply machines with precise doses of lubricant.
The researchers are now working to reduce the size of the pump to 10 mm2 in order to reduce production costs.