Smartpump – the World’s Smallest Microdosing Pump

Why do we need this new technology?

The Smartpump is a miniature lab »to go«. It fits inside a mobile phone or a jacket seam and can be attached to the skin with an adhesive patch or even implanted inside the human body. Combined with the right kinds of sensors, it can measure factors such as particulates, toxic gases, humidity, and insulin levels. It can also be used as a micropump to deliver tiny doses of gas or liquid. The Smartpump unlocks possibilities for new solutions wherever small mobile analysis and dosage options add value – for example, as part of an early warning system or for medical applications.

Who will benefit from the new technology?

The potential applications are many and diverse. For example, the Smartpump enables particulate measurements via mobile phone for personal health protection purposes, or it can issue individual warnings of toxic gases for firefighters working in the field. Medical applications include measuring insulin levels in people with diabetes or providing glaucoma therapy, in which the micropump could be implanted as a way to regulate pressure inside the eyes. The pump could also be used to deliver precisely calibrated doses of lubricant to precision mechanics inside devices.

How does the new solution work?

“Our Smartpump measures only 25 square millimeters, making it the world’s smallest pump. That said, it still has a high compression ratio,” explains Dr. Martin Richter, who is in charge of the Micro Dosing Systems department at the Fraunhofer Research Institution for Microsystems and Solid State Technologies EMFT in Munich. To generate pressure inside the pump chamber, the team of researchers use the piezoelectric effect, which converts electric voltage to mechanical energy. With the help of alternating current voltage, the silicon membrane is moved up or down, and ambient air is sucked in through a valve, compressed inside the pump chamber, and then expelled back out.

What makes the project unique?

Conventional piezoelectric micro diaphragm pumps can only generate relatively low pressures with air. This is because the asymmetry inherent in the piezo effect requires that there be a lot of room inside the pump chamber so the membrane can move. And that inevitably results in a lot of »dead« volume. The team of researchers have succeeded in reducing this dead volume, thereby increasing the pressure and suction capacity. The diaphragm is prestressed with a defined piezo effect early on during the assembly stage. This eliminates the need for a deep pump chamber and enables higher compression ratios and micropumps that are even smaller overall.

Not only the diaphragm itself, but also the flap valves and pump chamber are made of single-crystal silicon, which offers numerous advantages over metals and plastics. Silicon, which is classed as a metalloid, is elastic and not subject to fatigue. The individual pump components can also be etched out of the silicon layer with great accuracy and then joined together. The drawback is that silicon is relatively expensive. That is another reason it is important to make the pump as small as possible.

Building gas sensors into smartphones is currently a difficult proposition for a number of reasons, including the fact that response times for these sensors are much too long. The Smartpump could target the gas sensors with a supply of air, thereby shortening the response time from several minutes to two seconds.

Why is the Fraunhofer Future Foundation supporting this project?

The support provided by the Fraunhofer Future Foundation is laying the technological groundwork for the Smartpump to be used in applications including smartphones. The goal is to prepare the technology for a wide range of applications, so it can then be used on a large scale.