The units are also suitable for cleanrooms and can be regulated during operation. With the prototype of a new type of vacuum pump, the team led by Professors Stefan Seelecke and Paul Motzki from Saarland University was able to continuously draw a vacuum of up to 300 mbar pressure.
Electrical voltage sets films in motion
The new vacuum pumps, as well as pumps and valves, work with thin silicone films that are set in motion solely with the help of electrical voltage. "The technology is inexpensive to manufacture and the components are lightweight, which helps to save space and weight. In addition, these pumps and valves are considerably more energy-efficient than current processes," says Motzki. "Compared to a commercially available process valve for compressed air with an electromagnet, the same valve with our drive consumes 400 times less energy," explains the Professor of Smart Material Systems for Innovative Production at Saarland University and Managing Director of the Center for Mechatronics and Automation Technology (Zema). These processes also do not require rare earths or copper. And unlike compressor-driven pumps, the film counterparts are also quiet.
The 50 µ thick films are printed on both sides with an electrically conductive, highly stretchable electrode layer so that they can move at will. When the engineers apply an electrical voltage here, the film compresses vertically due to the electrostatic attraction and expands across its surface. By changing the electrical field, the researchers can make the film perform infinitely variable lifting movements or vibrate at any frequency and oscillation. The foil can also hold any desired position without consuming any electricity.
Foils also act as position sensors
"The dielectric elastomers also provide the function of a position sensor," says Motzki. Every deformation of the film can be assigned to a measured value of the electrical capacitance. The engineers use the measured values to determine how the film is mechanically deflected. In a control unit, they can use these measured values to program motion sequences with the help of artificial intelligence. Used as a drive in the corresponding equipment, the foils draw and release a vacuum at the desired pressure in motorless pumps, precisely dose liquids as a valve or act as stepless switches.
The foil pumps and valves can also monitor their own condition and signal where the fault lies. The measured values reveal if something is going wrong, for example if the vacuum has not been drawn correctly or if the valve or pump is blocked by a foreign object. If this happens in large industrial plants today, troubleshooting can sometimes be complicated.
The technology is also easy to scale. "To do this, we connect our actuators and pump chambers either in parallel or in series or both at the same time and can thus increase the pressure and volume flow," says Motzki.