Touch-sensitive robot metamorphosis could lead to better synthetic organs

A new robot capable of changing the geometry of its smooth surface quickly and precisely to interact with objects and liquids, react to human touch and display letters and numbers, all at the same time. Something out of a science fiction film? Not any more.

Researchers at the Max Planck Institute for Intelligent Systems and the University of Colorado Boulder have created a display for high-performance applications that could be adopted in the future by factory floors, clinical laboratories or even at home. Displays with shape-shifting surfaces are a class of robotic devices that generate surface geometries in response to actuation. In general, shape change can be induced by various methods, however, existing approaches usually face disadvantages that limit applications, such as surface discontinuity, high temperatures of the actuation surface, low fidelity of possible surface geometries that limits interaction, the need for large external devices such as magnetic plates, tracking systems or pumps, among others.

The researchers describe the novelty as an “iPad with a surface that can transform and deform”. The approach promises to address these limitations by integrating high-speed robotic sensors and actuators with natural mechanical compliance.

In a study published in Nature Communications on 31 July, engineers created a screen with the ability to change shape that fits on a gaming table. The device is made of a 10-by-10 grid with soft robotic “muscles” that can sense external pressure and create patterns. It can also reproduce the sense of touch.

The innovation is based on a class of soft robots first created by a team led by Christoph Keplinger, former assistant professor of mechanical engineering at CU Boulder and now director of the Max Planck Institute for Intelligent Systems. They are called hydraulically amplified self-correcting electrostatic actuators (HASEL). The display prototype is not yet ready to be taken to market, but the researchers predict that in the future similar technologies could lead to sensory gloves, to a smart conveyor belt for separating apples from bananas, for example, or used with virtual games in the entertainment sector.

“We can imagine organising these sensing and actuating cells in any shape and combination. There really is no limit to what this type of technology can ultimately do,” explains Mantas Naris, lead co-author of the article and PhD student in the Department of Mechanical Engineering.

Origin of the work

The project originated in the search for a different type of technology, synthetic organs. Artificial organs can help develop medical devices or robotic surgical tools at a much lower cost than using real animal tissue, according to Mark Rentschler, also a co-author of the study and a professor of mechanical engineering and biomedical engineering.

However, when developing this technology, the team came up with the idea of a tabletop display, roughly the size of a chessboard and made up of small squares arranged in a grid. Each of the 100 squares is a HASEL actuator, made of plastic bags in the shape of tiny accordions. When an electric current is passed through them, the fluid moves inside the bags, causing the accordion to expand and jump. The actuators also have soft magnetic sensors that can detect when you touch them.

Other research groups have developed similar smart boards, but smoother, taking up much less space and much faster. Each of the “robotic muscles” can move up to 3,000 times a minute.

The researchers are now concentrating on reducing the actuators and increasing the screen resolution. In addition, they are working on turning the display inside out in order to design a glove capable of poking the fingertips and thus “feeling” objects in virtual reality environments.

“Shape-shifting displays aren’t exactly new, but this system is special because it’s smaller, faster, quieter and smoother. Its processing and energy consumption requirements are low. What’s more, it’s a continuous surface, not discrete points, and that allows us to do some unique things,” Rentschler told the IEEE Spectrum website. The researcher hopes to make the system even more compact in the future.