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Wherever a vacuum is required – from applications in manufacturing and automotive engineering to laboratory and research work – this new technology is opening up access to lightweight, flat and energy-efficient pump architectures. Professor Paul Motzki’s team at Saarland University is showcasing a new vacuum pump prototype at Hannover Messe from 20 to 24 April (Hall 11, Stand D41).
The researchers apply an electrical voltage and immediately the polymer film begins to move. At just 50 micrometres thick, this ultrathin membrane has about the same thickness as a human hair. By adjusting the electrical voltage applied, researchers in Professor Paul Motzki’s team can make the film undergo powerful pulsing motions, vibrate at a desired frequency or amplitude, rise and fall in a smooth undulating motion, or hold a fixed position. What may sound like a neat party trick is, in fact, the basis for a new class of miniature actuators.
Because the motion of the film can be precisely controlled, it can be used to deliver 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 Saarbrücken team is integrating these smart films into vacuum pumps that can draw air or liquid out of 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 and without a motor
The film technology being developed in Saarbrücken eliminates the need for heavy components and enables lightweight, compact pump designs. ‘Using dielectric elastomers – as these electrically responsive polymer films are known – we can tailor pump geometries to specific requirements. That means that we can create forms that would not be technically feasible using conventional approaches. For example, we can produce extremely thin, flat designs comparable to the shape of a smartphone,’ says Paul Motzki, who is Professor of Smart Material Systems at Saarland University and Scientific Director/CEO at the Center for Mechatronics and Automation Technology in Saarbrücken (ZeMA). The film-based pumps operate reliably in compact, sensitive environments. A major benefit of dielectric elastomer technology is that it does not need expensive or hard-to-source materials like copper or rare earth elements. And because it operates without lubricating oil, it is ideally suited for applications in cleanrooms and sterile settings. ‘Depending on the operating mode, our membrane pumps can also be very energy efficient,’ says Motzki. Their pumps also run very quietly – an advantage that could significantly reduce background noise levels in production halls and assembly lines.
The more film-based actuators you use, the greater the power you get
At this year’s Hannover Messe, Paul Motzki‘s team is exhibiting a new prototype that illustrates how their technology can be scaled. Their latest vacuum-pump prototype is equipped with a dual drive. Last year, the team presented a single film drive in a single pump chamber. This year, they are showcasing a dual-drive prototype that features two film actuators in two pump chambers. ‘We can connect the two actuators either in parallel or in series, increasing pressure, volumetric flow rate and overall power,’ explains Motzki.
The two film-based drives can operate in opposing phases, with one side in intake mode, while the other discharges. This prevents performance drop-off and allows the pump to deliver higher flow rates and greater pressure capability – generating a continuous vacuum quickly and without cycling. The new dual-actuator design delivers a marked performance gain. Whereas the single chamber pump was able to achieve an absolute pressure of approximately 300 mbar, the new system can get down to below 200 mbar absolute. ‘And we can connect additional membranes in series or parallel to tailor and further boost performance – depending on application needs,’ says Motzki.
Another step towards industrial deployment
‘The new version of our pump is another step towards industrial use,’ says Paul Motzki. He and his team have been developing their dielectric elastomer technology for years across a range of research projects. A dielectric elastomer is a thin polymer film, both sides of which are coated with a highly flexible electrically conductive layer. When the researchers apply a voltage to the elastomeric polymer film, these electrically conducting layers attract each other, compressing the film and causing it to expand out sideways, thereby increasing its surface area. ‘By varying the electric field, we can control the motion of the elastomer film very precisely – making it execute continuously variable flexing motions or make it pulse or flex at some required frequency and amplitude,’ explains Motzki. Or they can make the film hold a fixed stationary position without requiring the continuous supply of electrical energy, as the dielectric elastomer only consumes power when it is actively moving. The Saarbrücken researchers use the film as a mechanical drive – a miniature motor that requires no additional sensors.
‘These films are self-sensing,’ says Paul Motzki. This self-sensing capability is inherent to dielectric elastomers: even the slightest movement changes the measured electrical capacitance of the film. Each deformation of the film produces a characteristic measurement signature, which the engineers can then use to precisely quantify the spatial configuration of the film at any one moment. By combining the capacitance data and AI-based machine learning, the team has developed a control unit that can predict and program motion sequences and thus precisely control how the elastomer film deforms. The same data can also be used for condition monitoring: it indicates, for example, if a foreign object is blocking the pump or if a safe vacuum has not yet been achieved.
In addition to developing motor-free vacuum pumps, Motzki’s team is using this technology for a wide range of other applications, from robotic grippers and loudspeakers to smart textiles and haptic feedback systems for smartphone displays. For example, the team has developed a smart industrial glove that can respond to how the operator’s hand and fingers move and communicate this information to a computer.
At Hannover Messe, the research team is looking for partners with whom they can develop applications that bring their film-based pump technology to market.
Background
Dielectric elastomer technology continues to be explored and developed in numerous Master’s and doctoral research projects. The results have been published as papers in a variety of scientific journals. The research work 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 ERDF projects iSMAT and Multi-Immerse. Additional funding has also come from ME Saar (the Association of Metalworking and Electrical Industries in Saarland).
To facilitate the transfer of their research results into the commercial and industrial sectors, the researchers at Saarland University established the company ‘mateligent GmbH’, which is also exhibiting at the same stand at this year’s Hannover Messe.
Questions can be addressed to:
Professor Paul Motzki, Smart Material Systems for Innovative Production, Tel.:+49 681 85787-13; Email: paul.motzki(at)uni-saarland.de
imsl.de – Intelligent Material Systems Lab
zema.de – Center for Mechatronics and Automation Technology (ZeMA)
Press photographs:
Press photographs can be used free of charge with this press release or in connection with reports about Saarland University provided that a photo credit with the photographer’s name is included.
