The researchers apply an electrical voltage, and the polymer film immediately begins to move. At just 50 micrometers thick, this ultrathin membrane is about the same thickness as a human hair. By adjusting the applied electrical voltage, the researchers in Professor Paul Motzki's team can make the film perform powerful pulsating movements, vibrate at the desired frequency or amplitude, rise and fall with a gentle undulating motion, or hold a fixed position. What might seem like a simple party trick is, in fact, the basis of a new class of miniature actuators.

Because the film's movement can be precisely controlled, it can be used to exert localized pushing and pulling forces, generating movements that would otherwise require motors or compressed air systems—both of which need space, energy, and maintenance. The team in Saarbrücken is integrating these smart films into vacuum pumps capable of extracting air or liquid from a chamber. Vacuum pumps are ubiquitous and indispensable in industrial applications ranging from packaging machinery and robotic grippers to medical technology.

Creating a vacuum without compressed air or a motor:
The sheet technology being developed in Saarbrücken eliminates the need for heavy components and enables lightweight, compact pump designs. “By using dielectric elastomers—as these electrically responsive polymer sheets are known—we can tailor the pump geometry to specific requirements. This means we can create shapes that wouldn’t be technically feasible with conventional approaches. For example, we can produce extremely thin, flat designs comparable to the shape of a smartphone,” says Paul Motzki, Professor of Intelligent Materials Systems at Saarland University and Scientific Director and Managing Director of the Saarbrücken Center for Mechatronics and Automation Technology (ZeMA). Sheet-based pumps operate reliably in compact and sensitive environments. A key advantage of dielectric elastomer technology is that it doesn’t require expensive or hard-to-obtain materials such as copper or rare-earth elements. And, since it operates without lubricating oil, it is ideal for cleanroom and sterile environments. “Depending on the operating mode, our diaphragm pumps can also be very energy efficient,” says Motzki. Furthermore, their pumps operate very quietly, an advantage that could significantly reduce background noise levels in production halls and assembly lines.

The more film-based actuators used, the greater the power output.
At this year’s Hannover Fair, Paul Motzki’s team is presenting a new prototype that illustrates how their technology can be scaled up. Their latest vacuum pump prototype is equipped with a dual drive. Last year, the team presented a single-film drive in a single pumping chamber. This year, they are presenting a dual-drive prototype featuring two film actuators in two pumping chambers. “We can connect the two actuators in parallel or in series, increasing the pressure, volumetric flow rate, and total power,” explains Motzki.

The two diaphragm-based drives can operate in opposite phases, with one side in suction mode while the other discharges. This prevents performance drop-off and allows the pump to deliver higher flow rates and greater pressure capacity, generating a continuous vacuum quickly and without cycling. The new dual-actuator design offers a significant performance improvement. While the single-chamber pump was capable of reaching an absolute pressure of approximately 300 mbar, the new system can operate at pressures below 200 mbar absolute. “And we can connect additional diaphragms in series or parallel to further adapt and enhance performance, depending on the application requirements,” says Motzki.

Another Step Toward Industrial Implementation
“The new version of our pump represents another step toward industrial use,” says Paul Motzki. He and his team have spent years developing their dielectric elastomer technology in various research projects. A dielectric elastomer is a thin polymer film coated on both sides with a highly flexible, electrically conductive layer. When researchers apply a voltage to the elastomeric polymer film, these electrically conductive layers attract each other, compressing the film and causing it to expand laterally, increasing its surface area. “By varying the electric field, we can control the movement of the elastomer film with great precision, making it perform continuously variable bending movements or pulse or flex at a specific frequency and amplitude,” Motzki explains. Alternatively, they can make the film hold a fixed position without requiring a continuous supply of electrical power, as the dielectric elastomer only consumes energy when it is actively moving. Researchers in Saarbrücken are using the film as a mechanical drive: a miniature motor that requires no additional sensors.
“These films are self-sensitive,” says Paul Motzki. This self-sensitivity is inherent to dielectric elastomers: even the slightest movement alters the film’s measured electrical capacitance. Each deformation of the film produces a characteristic measurement signature, which engineers can use to precisely quantify the film’s spatial configuration at any given time. By combining the capacitance data with AI-based machine learning, the team has developed a control unit capable of predicting and programming movement sequences and thus precisely controlling how the elastomer film deforms. The same data can also be used for status monitoring: it indicates, for example, whether a foreign object is blocking the pump or whether a safe vacuum has not yet been achieved.

In addition to developing motorless vacuum pumps, Motzki's team is using this technology for a wide range of other applications, from robotic grippers and speakers to smart textiles and haptic feedback systems for smartphone screens. For example, the team has developed a smart industrial glove that can respond to the operator's hand and finger movements and communicate this information to a computer.

At the Hannover Fair, the research team is seeking partners to develop applications that will bring their sheet-based pump technology to market.

Background:
Dielectric elastomer technology continues to be explored and developed in numerous Master's and PhD research projects. The results have been published as articles in various scientific journals. The research has also received support from numerous sources, including the EU and the German Research Foundation (DFG). The Saarland State Government has provided financial support through the FEDER iSMAT and Multi-Immerse projects. Additional funding has also been received from ME Saar (the Saarland Association of Metallurgical and Electrical Industries).
To facilitate the transfer of their research results to the commercial and industrial sectors, researchers from Saarland University established the company mateligent GmbH, which is also exhibiting at the same stand at this year's Hannover Fair.