Flexible, skin-mounted haptic interface can seamlessly bridge virtual and real-world experiences

Immersing oneself in the virtual and augmented reality world is not only awesome for entertainment, it helps industries like manufacturing and medicine operate more efficiently. Nevertheless, as fast as the technology brings you into the world, the weight and stiffness of its hardware can just as easily remind you that you aren’t really golfing on the PGA tour or preparing for a surgery.

Inspired by Softbotics, researchers in the Soft Machines Lab at Carnegie Mellon University are developing wearable electronics to augment our senses with natural-feeling hardware. A paper published this week in Nature Electronics illustrates how a flexible, skin-mounted haptic interface can seamlessly bridge virtual and real-world experiences without unnecessary distractions.

“We are building imperceptible technology,” said Carmel Majidi, professor of mechanical engineering at Carnegie Mellon University and head of the Soft Machines Lab. “This is technology to assist us that won’t cause distractions, doesn’t require a big cognitive load, and won’t take away from other areas of our lives that require our full attention.”

Roughly the size of a thimble, the wireless, flexible, lightweight, and skin-mountable haptic interface is able to communicate with the wearer through eleven distinct, multi-directional movements. The device is powered by a soft, serpentine-structured shape memory alloy (SMA) actuator. An epoxy probe serves as a barrier between the actuator and user to protect the skin from any heat generated by the SMA.

“Typically if you want to replicate different motions, you need to have multiple actuators. We have achieved very rich tactile feedback using one single actuator which makes the device more robust and versatile,” said Majidi.

To demonstrate the device’s versatility, the team deployed it in three different scenarios:

1. Virtual reality
   Equipped with a VR headset, a user wearing the device was able to feel physical sensations while interacting with a virtual object.
    
2. Daily activity
   When the device was synchronized with a camera, a user was able to hang a painting on a wall in a desired location with guidance from the wearable. Differentiated tapping patterns replaced the infamous language cues, “Higher! Lower! To the left!” that typically accompany hanging home decor.
    
3. Object detection
   Blindfolded, a user was able to find specific objects on a table via directional cues from the wearable. This demonstration highlights the potential for haptic interface devices to augment sensing capabilities for patients with visual impairments.

“The scalability, versatility, quick response time, discreetness, and ability to transcend language and cultural barriers makes our haptic feedback device a universally accessible solution,” said Majidi.

The team is hopeful that this technology can provide substantial benefits to everyday life. They plan to continue developing it for other applications like wearable human-machine interfaces. One day, it may enable humans to teach a robot to play a musical instrument or complete a precise surgery – or vice versa.

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Additional contributors to this research from Carnegie Mellon University include Beomchan Kang, Nathan Zavanelli, Guo Ning Sue, Dinesh Patel, Subin Oh, and Michael Vinciguerra. In partnership with Saewoong Oh from Korea Advanced Institute of Science and Technology and Wei Dawid Wang from Hanyang University.

About Carnegie Mellon University
Carnegie Mellon, cmu.edu, is a private, internationally ranked research university with acclaimed programs spanning the sciences, engineering, technology, business, public policy, humanities, and the arts. Our diverse community of scholars, researchers, creators, and innovators is driven to make real-world impacts that benefit people across the globe. With a bold, interdisciplinary, and entrepreneurial approach, we do the work that matters.

About the College of Engineering
The College of Engineering at Carnegie Mellon University is a top-ranked engineering college that is known for our Advanced Collaboration culture in research and education. The College is well-known for working on problems of both scientific and practical importance. Our “maker” culture is ingrained in all that we do, leading to novel approaches and transformative results. Our acclaimed faculty have a focus on innovation management and engineering to yield transformative results that will drive the intellectual and economic vitality of our community, nation, and world.