Skin-Mounted Haptics Enhance the Senses

At Carnegie Mellon University’s Soft Machines Lab, robots aren’t hard boxy computers completing mundane tasks. Instead, they’re flexible, pliable, and attachable to our own skin and capable of expanding the user’s senses. 

“For years, we’ve been working on soft robotics, building robots out of soft materials, with the hope that we could make machines and robots a little bit more lifelike,” said Carmel Majidi, professor of mechanical engineering at Carnegie Mellon University and head of the Soft Machines Lab. “Instead of using bulky motors and gears, we would have soft and flexible, compliant, stretchable materials.”  

Inspired by robots performing tasks in the environment, Majidi’s team wondered if they could create a tool to interact with humans instead. The result is a wearable device that expands the user’s senses, demonstrating how flexible, skin-mounted haptics can bridge reality with the digital world.  

The researchers’ findings were recently published in Nature Electronics. 
 

Shape memory materials 

Imagine that you are hanging a picture. Instead of your annoyed partner saying, “Left, left, up a little, left,” this finger-mounted haptic would give you increased senses to know exactly where to go through tiny physical sensations on your skin. 

Or, if someone with a visual impairment wanted to use virtual reality to identify an object on the counter, the wireless, skin-mounted, thimble-sized device would provide guidance to the right place.  

“You’re getting visual cues when you interact with objects, but now, because of this cutaneous feedback, you can also feel the objects that you’re touching,” Majidi said. 
   
The device’s haptic interface communicates with the wearer through 11 distinct, multi-directional movements. It’s powered by a soft, serpentine-structured shape memory alloy (SMA) actuator, while an epoxy probe provides a barrier between the actuator and user to protect the skin from any heat generated by the SMA. 

“We found SMAs to be particularly useful for creating the limbs of soft robots, to get them to kind of crawl and jump and swim and get all sorts of motions,” he said. “The big insight here was this ability to use these shape memory materials to provide a range of different types of sensations to the human body on a finger-mounted device that itself was soft and rubbery.” 

You May Want to Read: Fluorine-Free Polymer Redefines Wearable Tech

Right now, applying the device to the finger works best. But progress likely won’t stop there.

“In principle, you could put cutaneous devices anywhere on the body. It’s just that your finger just has so many mechanical transducers. There’s a high density of mechanical transducers that tends to be where it’s kind of most effective,” Majidi said. “It’s a tingling motion, rubbing motion, a vibration, and not so much a scratching but a rubbing feeling. They can convey a lot of information back to the human.” 
 

The future of reality 

Virtual reality offers the chance to see a whole world of new places and experiences, but with this type of wearable, you can actually feel it too.  

“It’s the biggest opportunity or application for a technology like this,” he said. Years into the future, students might head on a virtual field trip to a museum or archaeological site where they aren’t just looking around but feeling what it would be like “in real life.” 

One area he sees potential for application is performing surgery with a robot, similar to the da Vinci robot’s joystick with integrated haptics. 

“This would further augment that and make it a richer experience for the surgeon so they can be more effective,” he said.  

It also has the potential to help with physician training for those procedures. 

Discover the Benefits of ASME Membership

Another application is in space. 

“If you’re trying to do design work like actively having a robot operate in some dangerous or remote environment, or you want to see what it’s like to be in that environment so you can make better design decisions,” he said. 

Since the materials themselves are pretty “mature” and abundant, and have already been used in commercial products, “the technology itself is pretty far along,” Majidi said. “The biggest [next step] is commercial demand and the push from consumers.” 

Majidi and his team are continuing their research on behalf of HAND-ERC, which is a collaboration between multiple universities on training and teaching robots—another place where these new wearables could be applied. 

Alexandra Frost is a freelance writer and content strategist in Cincinnati.