Wearable haptic devices, which provide touch-based feedback, can provide more realistic experiences in virtual reality, assist with rehabilitation, and create new opportunities for silent communication. Currently, most of these devices rely on vibration, as pressure-based haptics have typically required users to wear stiff exoskeletons or other bulky structures.Now, researchers at Stanford Engineering have designed a comfortable, flexible knit sleeve, called Haptiknit, that can provide realistic pressure-based haptic feedback. Their design, published Dec. 18 in Science Robotics, shows that pressure may be more effective than vibration for some applications and is the first step toward a new category of haptic devices.“A device like this opens up a lot of new possibilities for user interfaces – how we experience virtual environments, how we experience remote communication,” said&nbsp;<a href="https://profiles.stanford.edu/allison-okamura" data-extlink="">Allison Okamura</a>, the Richard W. Weiland Professor of Engineering at Stanford and senior author on the paper. “It’s much more lightweight, wearable, and comfortable.”<h2>A knit solution</h2>Okamura and her colleagues designed a battery-powered pneumatic system with pressure actuators that were essentially small, inflatable pouches that could be rapidly filled with air. But they needed a way to hold those pouches against the skin without using a clunky exoskeleton.“If you put air into a balloon next to your skin but don’t anchor it there, it’s going to expand in all directions,” said Cosima du Pasquier, a postdoctoral researcher at Stanford and first author on the paper. “You’re going to waste most of the inflation potential.”Du Pasquier, who makes clothes as a hobby, realized that knit fabric might hold the answer. The researchers designed a soft textile that would be stiff in some areas – creating an inflexible backing to hold the pressure actuators against the skin – and flexible where needed to allow for movement and comfort.They worked with a team at MIT’s Self-Assembly Lab to manufacture the Haptiknit sleeve prototype on a knitting machine, with space for eight actuators arranged in two rows. Most of the sleeve was knit from nylon and cotton, but the areas backing each actuator also included a thermoplastic fiber. Once the knitting was done, the researchers used heat to melt the thermoplastic fibers and cause them to harden, stiffening those areas.<iframe width="640" height="360" src="https://www.youtube.com/embed/il4lICuOIAc?&amp;wmode=opaque&amp;rel=0&amp;enablejsapi=1&amp;origin=https://www.wevolver.com" frameborder="0" allowfullscreen="" class="fr-draggable" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true"></iframe>Demo video of the “Knit Haptic Pneumatic Sleeve” | Skylar Tibbits, MIT Self-Assembly Lab“A challenge in the field of soft robotics is how do you stick together something hard and something soft – they tend to delaminate,” Okamura said. “But putting these fibers into knitting makes a totally seamless transition from parts that are hard to parts that are soft, because it’s one continuous fabric.”The researchers tested the Haptiknit prototype with 32 users. They found that people could more accurately discern the location of individual touches from the pressure actuators than from a similarly arrayed vibrational device. Okamura and her colleagues also tried inflating the actuators consecutively at different speeds to try to create the feeling of a pleasant stroke, as opposed to discrete touches (or the potentially unpleasant feeling of a spider crawling up one’s arm). In general, participants found faster, more overlapping indentation mimicked the feeling of a continuous stroke – the opposite of what the researchers had found for vibration.The third test was to see if participants could recognize six emotions – attention, gratitude, happiness, calming, love, and sadness – conveyed through the pressure signals. The researchers used touch patterns established in previous research and found that participants generally guessed correctly at a higher-than-chance rate, although the gestures for “calming” and “love” were easily confused.<h2>More comfortable haptics</h2>Overall, participants found the Haptiknit sensations to be equally or more pleasant than those caused by vibrations. They also described the prototype sleeve as comfortable and easy to use, which is promising for more long-term uses.“What was particularly interesting was that there was a correlation between whether someone had tried a haptic device before and how highly they rated the comfort of our sleeve,” du Pasquier said. “Essentially, if they had tried out other haptic devices, they scored our sleeves much higher.”With more lightweight, comfortable haptic devices, the researchers are envisioning new opportunities for conveying information through touch. Haptiknit could be used to aid in navigation, military communication, and even dog training, du Pasquier said.Okamura, du Pasquier, and their colleagues are working on refining and optimizing their knitting patterns, as well as creating larger-scale devices – perhaps even a full suit – for virtual reality interactions. They also hope to incorporate this work into assistive devices that can help people move or aid in rehabilitation.“We can use this to start testing how people actually interpret and respond to this type of haptic information,” Okamura said. “Whether the purpose is entertainment, communication, training, or physical assistance, this really brings these wearable devices toward things that people might actually want to use in their everyday lives.”&nbsp;<hr>Okamura, a professor of mechanical engineering, is a member of<a href="http://biox.stanford.edu/" data-extlink="">&nbsp;Stanford Bio-X</a>, the<a href="https://humanperformance.stanford.edu/" data-extlink="">&nbsp;Wu Tsai Human Performance Alliance</a>&nbsp;and the<a href="https://neuroscience.stanford.edu/" data-extlink="">&nbsp;Wu Tsai Neurosciences Institute</a>, a faculty affiliate of the<a href="https://hai.stanford.edu/" data-extlink="">&nbsp;Institute for Human-Centered Artificial Intelligence</a>, a science fellow at the&nbsp;<a href="https://www.hoover.org/" data-extlink="">Hoover Institution</a>, an executive committee member for the&nbsp;<a href="https://src.stanford.edu/" data-extlink="">Stanford Robotics Center</a>, and a faculty member of the&nbsp;<a href="https://centerfordesignresearch.stanford.edu/" data-extlink="">Center for Design Research</a>.Additional Stanford co-authors of this research are visiting students Ian Scholl and Liana Tilton.Other co-authors of this work are from the Massachusetts Institute of Technology and the University of Houston.

Haptiknit sleeve worn on the arm, including the control system on the upper arm. | Susan Williams, MIT Self-Assembly Lab

Researchers at Stanford Engineering have developed a lightweight, comfortable knit sleeve that uses pressure-based haptics to simulate touch, opening up new possibilities for wearable devices.

New knit haptic sleeve simulates realistic touch

This article was discussed in our <a href="https://www.wevolver.com/profile/the.next.byte" rel="noopener noreferrer" target="_blank">Next Byte podcast</a>.&nbsp;<iframe height="200px" width="100%" frameborder="no" scrolling="no" seamless="" src="https://player.simplecast.com/d57569bc-03b3-422f-b7d5-738ddd6707a9?dark=false" class="fr-draggable" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true"></iframe> The full article will continue below.<hr>Back pain is one of the main causes of everyday discomfort and sick leave in the western world. The reason for this is often a lack of exercise in the sedentary office routine combined with a lack of compensatory activities such as sport and gymnastics. The aim of the spin-off StraightUp by three graduates of the Karlsruhe Institute of Technology (KIT) is to combat back pain in the long term and sustainably with an innovative idea. To this end, they have developed a wearable textile product that uses woven elastic wires and appropriate sensors to measure the shoulder position and inclination of the back and ensures a sustainable improvement in posture through haptic feedback.Previous posture stabilizers are designed to simply fix the back, which in the long term severely limits the mobility of the user. Other approaches with built-in inclination sensors that trigger a vibration impulse when the body bends forward have the disadvantage that many everyday and sports activities take place in a forward-leaning position and thus lead to incorrect vibration impulses.<h2>Novel approach using elastic metal alloy and AI implementation</h2>The spin-off StraightUp is tackling this problem with an innovative idea. Erik Vautrin, Marcus Hamann-Schroer and Jan Bartenbach, three KIT graduates, in collaboration with physiotherapist Tobias Baierle, developed the vision of a wearable textile that can measure the shoulder position and inclination of the back using elastic wires incorporated into the fabric. Using the data obtained from this and a woven-in chip controlled by artificial intelligence (AI), the system generates haptic feedback through vibrations, which is intended to encourage users to correct their posture. The use of the sensors in the wearable was made possible by a conductive super-elastic metal alloy that adapts to the movements of the person wearing it. "Through the haptic feedback, the body learns to maintain a healthier posture on its own, which leads to long-term improvement. The feedback system promotes active shoulder blade stabilization and posture correction of the spine," explains Baierle. The wearable can be worn in everyday life as well as during leisure and sports activities.<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNzI2MTAxNjg5MjI5LTIwMjRfMDY5X0lubm92YXRpdmVzIFdlYXJhYmxlX0tvZXJwZXJoYWx0dW5nIG5hY2hoYWx0aWcgdmVyYmVzc2VybkJpbGQyXzcyZHBpLmpwZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6OTUwLCJmaXQiOiJjb3ZlciJ9fX0=" style="width: 100%px;" class="fr-fic fr-dib">Sustainable support for the back: StraightUp's concept relies on sensors, AI and haptic feedback. (Photo: StraightUp)<h2 id="isPasted">Further steps on the way to spin-off and market readiness</h2>The team is currently working with the German Institute for Textile and Fiber Research to enable the best possible integration of the sensors into the wearable. "This partnership brings us a big step closer to market readiness," explains Vautrin. In collaboration with doctors, physiotherapists and other specialists, optimization tests are to take place this year. The aim is to test the further developed product with potential customers at the end of the year.<h2>Support for founders at KIT</h2>The three founders of StraightUp met in the course “Microsystem product design for young entrepreneurs” at KIT. “In the course we learned the basics of developing and implementing a product idea. We also learned practical things like writing a business plan,” explains Bartenbach. The young team then met the physiotherapist Baierle through a lecturer.On their journey so far, the founders have used the support options at KIT. These include the KIT start-up forge and other offers from the KIT's Innovation and Relations Management (IRM) service unit. With the support of IRM, the StraightUp team successfully acquired an EXIST start-up grant for preparation and early-stage financing of the upcoming spin-off. "From the very beginning, we had a great impression of the competence of the individual people and how they interact with each other in the StraightUp team," says Dr. Rolf Blattner, Business Development Manager at IRM.&nbsp;

In the future, StraightUp could improve posture in everyday office life and thus reduce back pain, as demonstrated here in the prototype. (Photo: StraightUp)

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New knit haptic sleeve simulates realistic touch

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