A hand on a shoulder, the caress of an arm, or a simple hug. Human touch can bring calm, comfort, and closeness—a sense of security and protection. When the nerve cells in our skin are stimulated by touch, numerous parts of our brain are activated, triggering immediate changes in our body's biochemistry. Hormones and signaling molecules are released, including oxytocin, which creates a feeling of well-being and bonding. In contrast, video calls often leave us cold. We miss the closeness and emotional connection that in-person encounters produce. But what happens when physical closeness is essential, when children are seriously ill, but their parents cannot visit them? And what about when physical contact is not possible due to a weakened immune system?
An interdisciplinary research team from Saarland University, htw saar University of Applied Sciences, the Center for Mechatronics and Automation Technology (ZeMA), and the German Research Center for Artificial Intelligence (DFKI) is working on a technology that will allow children in hospital isolation wards to experience the physical proximity of their parents in a very natural way during virtual visits. The "Multi-Immerse" project lies at the intersection of engineering, neurotechnology, medicine, and computer science, and the research team is developing ways to facilitate multisensory virtual encounters between individuals. The goal is to create a new technology that allows young patients to see, hear, and feel their parents and siblings as realistically as possible, so that the children experience a strong sense of close physical interaction even when they are physically separated.
The research group led by Professors Stefan Seelecke and Paul Motzki at Saarland University and ZeMA in Saarbrücken is responsible for the tactile aspect of the project and for creating technical systems that provide a realistic sense of touch. The engineers in Saarbrücken are experts in using thin silicone films to give surfaces new capabilities. They have developed films just 50 micrometers thick that can be worn like a second skin. Just as our skin is the interface between our body and the outside world, these ultra-thin films are the interface between the body and the virtual world. The goal is to create a realistic tactile sensation from interactions between people in a virtual environment.
When incorporated into textiles, these high-tech films allow a child to experience touch when a parent strokes a second, smart textile elsewhere. The films, called dielectric elastomers, act both as sensors—detecting touch from mom or dad—and as actuators—transmitting those movements to the child,” explains Professor Seelecke, who heads the Intelligent Materials Systems Laboratory at Saarland University. When functioning as a sensor, the film can accurately recognize how a hand or finger presses or stretches it. This physical deformation caused by the parent’s hand is precisely reproduced in a second layer of tissue that is in contact with the child’s skin, giving them the realistic sensation of being stroked, for example.
A highly flexible, electrically conductive layer is printed on each side of the ultrathin film to create what is known as a dielectric elastomer. “If we apply a voltage to the elastomer film, the electrodes attract each other, compressing the polymer and causing it to expand laterally, thus increasing its surface area,” explains Professor Paul Motzki, holder of an interinstitutional chair in intelligent materials systems. for innovative production at Saarland University and ZeMA. The slightest movement of the film alters its electrical capacitance, a physical quantity that can be precisely measured. When a finger passes over the film, it deforms, and an exact electrical capacitance value can be assigned to each individual position of the film. A sequence of these measured capacitance values represents the path the finger follows as it moves. The film is, therefore, its own flexible sensor that can recognize how it is deforming.
By understanding how capacitance values and film deformations correlate, researchers can use smart textiles to transfer the stroking motion of a parent's hand to a child's arm. The research team can precisely control the movement of the elastomer film. Combining capacitance data with intelligent algorithms, the team has developed a control unit that can predict and program movement sequences, thus precisely controlling how the elastomer film deforms. “We can make the film perform controlled flexing movements continuously to exert increasing pressure on the skin, or keep it in a fixed position,” explains PhD student Sipontina Croce, who is working on her doctoral thesis within the project. They can also create tapping movements at a specific frequency. The amplitude and frequency of the movement can be precisely regulated.
At this year’s Hannover Fair, the team will demonstrate their technology with a “watch” to which a smart film has been applied on the back. “We can create chains of these smart components so they can transmit long, stroking movements. To do this, we interconnect the components so they can communicate and cooperate collectively within a network,” explains Paul Motzki.
This smart textile technology is inexpensive, lightweight, quiet, and energy-efficient. By adding a tactile element to computer games, the novel elastomer film technology can also be used to make the gaming experience more realistic. In related projects, engineers have used their technology to create interactive gloves for future industrial production processes, or to create the sensation of a touch "button" or "swipe" on flat glass screens, literally adding a new dimension to touchscreen interactions.
At this year's Hannover Fair, the smart materials experts from Saarbrücken will be showcasing other developments using dielectric elastomers, such as sensory T-shirts or shoe soles, or industrial components like high-performance pumps, vacuum pumps, and actuators.
Background:
The FEDER project "Multi-Immerse," led by Professor Martina Lehser (Saar University of Applied Sciences htw saar / ZeMA), is a collaboration involving the Saarland Center for Digital Neurotechnologies (CDNS), based at the Saarland University Medical Campus in Homburg, htw saar, and the Center for Mechatronics and Automation Technology (ZeMA). In addition to Professor Martina Lehser and Professors Stefan Seelecke and Paul Motzki, the project also includes research by Professor Daniel Strauss (Head of the Systems Neuroscience and Neurotechnology Unit), Professor Michael Zemlin (Director of the Saarland University Children's Hospital), Professor Eva Möhler (Head of the Department of Child and Adolescent Psychiatry at the Saarland University Medical Center), and computer scientists from Saarland University (Professor Jürgen Steimle) and the German Research Centre for Artificial Intelligence (DFKI).
The technology of dielectric elastomers continues to be developed by doctoral students conducting research as part of their doctoral thesis projects under the supervision of Professors Seelecke and Motzki. The results have been published in various scientific journals. The research has also received support from numerous sources. The EU has awarded a Marie Curie research grant. The Saarland government has provided financial assistance through the FEDER iSMAT and Multi-Immerse projects, and ME Saar (the Association of Metallurgical and Electrical Industries of Saarland) has funded a doctoral research program.
The team also aims to develop the results of its applied research for commercial and industrial applications, which is why the company "mateligent GmbH" was established from Professor Seelecke's department.
