Imagine navigating a virtual reality with contact lenses or operating your smartphone under water: This and more could soon be a reality thanks to innovative e-skins. A research team led by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) has developed an electronic skin that detects and precisely tracks magnetic fields with a single global sensor. This artificial skin is not only light, transparent and permeable, but also mimics the interactions of real skin and the brain, as the team reports in the journal Nature Communications.
Originally developed for robotics, e-skins imitate the properties of real skin. They can give robots a sense of touch or replace lost senses in humans. Some can even detect chemical substances or magnetic fields. But the technology also has its limits. Highly functional e-skins are often impractical because they rely on extensive electronics and large batteries. “Previous technologies have used numerous individual sensors and transistors to localize sources of a magnetic field, similar to touch sensors in a smartphone display. Our idea was to develop a more energy-efficient system that is more akin to our soft human skin and thus better suited for humans,” said Denys Makarov from the Institute of Ion Beam Physics and Materials Research at HZDR.
The new e-skins seamlessly track signal paths, enabling applications that recognize digital patterns, written by a magnetic stylus, touchless interactions in virtual reality, or operating a smartphone in extreme environments, even when diving. Often, the wearer of a magnetoreceptive artificial skin is not a human, but a machine.
At the same time, magnetic field sensors are less susceptible to interference than conventional electronics. Robotic systems could use them to detect movements, even in complex environments where other methods fail. In winter, users could operate a smartphone equipped with optically transparent magnetic sensors via a magnetic patch on the fingertip of a glove with no interference from third-party electronics. Magnetoreception does not act as a compass but offers a unique communication channel between humans and machines.
Here is an exclusive Tech Briefs interview, edited for length and clarity, with Makarov.
Tech Briefs: What was the biggest technical challenge you faced while developing this artificial skin?
Makarov: Magnetosensitive smart skins were already known. However, they had rather poor resolution in spatial localization of magnetic stimuli, they were energy inefficient, and they were not permeable for air and moisture as would be required for the comfort of users. With our work, we addressed these challenges. In particular, we realized mechanically imperceptible smart skins with perforations (i.e., openings), which enable efficient mixture and air exchange and do not hinder the functionality of magnetic field sensors. Furthermore, we applied the concept of electron tomography to magnetoresistive sensors, which allowed us to spatially localize a magnetic pointer (say a stylus with a magnet) with an accuracy of better than 1 mm. In addition, electron tomography allowed us to work with only one, yet global, sensing element, which helped to reduce energy consumption by two orders of magnitude compared to state-of-the-art magnetosensitive smart skins.
Tech Briefs: What was the catalyst for this project? How did the work come about?
Makarov: We were always concerned by distinct differences between magnetosensitive smart skins and human skin. Previous versions of magnetosensitive skin consisted of individual sensors distributed over the real skin. Signals from each sensor were separately measured, which added to the complexity and energy inefficiency of the entire concept. This is very different for our smart skins. We were inspired by the human body and tailored our magnetosensitive skins to work more like human skin. No matter where I touch real skin, the signal always travels through nerves to the brain, which processes the signal and registers the point of contact. Our e-skins also have a single global sensor surface — just like our skin. And one single central processing unit reconstructs the signal — just like our brain.
Tech Briefs: Can you explain in simple terms how it works please?
Makarov: We used very thin and mechanically flexible polymeric foils that are just a few micrometers thick. The entire membrane is optically transparent and perforated, making the artificial skin permeable to air and moisture, allowing the real skin underneath to breathe. This novel e-skin accommodates a magnetosensitive functional layer, which acts as a global sensor surface to precisely localize the origin of magnetic signals. Since magnetic fields alter the electrical resistance of the material, a central analysis unit is able to calculate the signal location based on these changes. This not only emulates the functioning of real skin but also saves energy. These large-area magnetosensitive smart skins are the main novelty of our work. This is made possible by electron tomography. This technology is new for e-skins with magnetic field sensors — it was previously considered too insensitive for the low signal contrast of conventional magnetosensitive materials. The fact that we validated this method experimentally is a major technical achievement of the work.
The new e-skins seamlessly track signal paths, enabling applications that recognize digital patterns, written by a magnetic stylus, touchless interactions in virtual reality, or operating a smartphone in extreme environments, even when diving.
Tech Briefs: Do you have any set plans for further research/work/etc.? If not, what are your next steps?
At the moment, we’re pushing forward the possibility to realize eco-sustainable magnetosensitive smart skins, which can be fabricated using green methods without harmful chemicals. This is an important milestone for the magnetic field sensing community aiming to minimize environmentally toxic electronic waste.
Tech Briefs: Do you have any updates you can share?
Makarov: We already developed magnetosensitive smart skins that can be transferred using a water-assisted transfer printing method to any surface including biological surfaces. These smart skins were successfully validated to work as human machine interfaces to digitize motion of our body in virtual reality.
Tech Briefs: Do you have any advice for researchers aiming to bring their ideas to fruition (broadly speaking)?
Makarov: The aim for energy efficiency of prospective electronics as well as their sustainability could give good guidance in determining an impactful research direction. The success of a project is usually determined by the competence and complementarity of the team members.
