Researchers Develop a Film that Gives Touchscreens a Third Dimension

Smartphone screens vibrate or pulse on demand, and thus can assist users to navigate through a menu or can guide a user’s finger to virtual on-screen buttons that can be developed or removed as per the user’s requirement.

Professor Stefan Seelecke and his colleagues at Saarland University have created a film that offers a third dimension to touchscreens. The thin and very lightweight silicone film can take on different forms and positions and can be made to carry out a pushing motion, a single pulse, a prolonged vibration, or a sudden jolt at a particular place on the screen. In addition, the polymer film shows sensor properties and can thus confer the device with an additional sense organ.

The team of Saarbrücken engineers will be presenting their technology at the 2019 Hannover Messe to be held from the April 1st to 5th, 2019 at the Saarland Research and Innovation Stand (Hall 2, Stand B46).

As the fingertip is moved across the smartphone screen, the user suddenly feels a pulsing sensation beneath their finger and a button magically emerges at that point on the screen. Otherwise, the user follows a perceptible signal that directs their finger across the screen to the place where the button is present. New technology created by Professor Stefan Seelecke and his research team at the Intelligent Material Systems Lab at Saarland University and at ZeMA (Center for Mechatronics and Automation Technology) in Saarbrücken enables buttons to appear and disappear at any location on the touchscreen of an IT device. The screen can direct the user’s finger to a virtual button at any preferred location on the screen by producing vibrations, pulses, or individual jolts that are sensed by the user’s fingertip. This new functionality offers a whole new range of possibilities for Internet searches, for satnav devices, and for computer games.

The foundation for this new generation of displays is a quite normal-looking sheet of silicone film—somewhat similar to a piece of household cling film.

The material the film is made from is known as a dielectric elastomer.”

Professor Stefan Seelecke, Department of Intelligent Material Systems, Saarland University.

Seelecke’s team has received several awards at international conferences for their research on these films.

The engineers in Seelecke’s team print an electrically conducting layer upon a very thin polymer membrane. This enables them to apply an electric voltage to the film. Since the film is “electroactive,” it shrinks in one direction and enlarges in the other on applying a voltage.

As a result of electrostatic attractive forces, the polymer film can, for example, be squeezed vertically, causing it to expand outwards.

Steffen Hau, PhD Engineer, Saarland University.

If the scientists change the electric field, the film reacts by carrying out complex choreographies and generates tactile signals ranging from high-frequency oscillations to pulsing motions similar to a heartbeat or continuous variable flexing motions. The prototype system that the research team is exhibiting at Hannover Messe integrates their new electroactive film with a smartphone’s touchscreen. This allows virtual buttons to be developed on the phone’s screen as well as offers a whole new range of added screen functions.

With the help of intelligent algorithms, the Saarbrücken team can convert a piece of polymer into a technical component whose performance can be precisely controlled.

We use the film itself as a position sensor and this imparts sensory properties to the display. There’s no need for any other sensors,” states Steffen Hau. The research team can accurately ascribe any variation in the position of the film to a change in the film’s capacitance. “This means that we always know exactly how the film is deforming at any specific moment. By measuring the capacitance of the dielectric elastomer, we can infer the exact amount of mechanical deformation in the film. By changing the applied voltage, we can precisely control the shape of the film,” describes Dr Hau. Any required series of motion can be estimated and programmed in the control unit.

As this technology does not rely on rare earths or copper, it can be manufactured cheaply, it consumes very little energy and the polymer films are astonishingly light.

Professor Stefan Seelecke, Department of Intelligent Material Systems, Saarland University.

The research being carried out in the Seelecke team on these deformable electroactive polymers is applications-focused research. Meanwhile, at Hannover Messe, the Saarbrücken engineers will be seeking commercial and industrial partners with whom they can advance their system into commercial products.

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