World's smallest pump helps smartphone sensor detect particulate matter

A smartphone with an inbuilt gas sensor could be used to warn of heavy exposure to particulate matter, which is harmful to the heart and lungs. To help the sensor respond quickly and provide accurate measurements, Fraunhofer researchers have developed a powerful micro diaphragm pump for delivering ambient air to the sensor.

“Our smart pump measures only 25 square millimetres, making it the world’s smallest pump. That said, it still has a high compression ratio,” said Dr Martin Richter, department head of micro dosing systems at the Fraunhofer Research Institution for Microsystems and Solid State Technologies EMFT in Munich.

Richter and his team used the piezoelectric effect to convert an applied electrical field into mechanical strain to generate pressure in the pump chamber. Alternating the voltage helps move the silicon membrane up or down, which draws ambient air through a valve and compresses it in the pump chamber before expelling it.

Conventional micro diaphragm pumps powered by piezoelectricity generate relatively low pressure with air. According to the group, the asymmetry of the piezo effect means a lot of room is required in the pump chamber to move the membrane. This results in a high volume of residual gas within the chamber, an issue that was resolved by Richter and his team.