Bionic Limbs Research News April 11, 2021

Indestructible Bionic Hand Feature Image

As part of our mission to help those with limb differences learn about bionic limb technology, we periodically report on the latest research news. Below are the most interesting stories that we uncovered this past week.

The Coming Leap in Bionic Hand Dexterity & Durability

Because we interact with so many bionic hand users, we are keenly aware of their frustrations. Fragility is a major complaint, while a lack of dexterity inhibits user control.

Here is a look at a bionic hand prototype that addresses both these issues:

And here is a bonus video to get you even more excited:

Unfortunately, this hand isn’t available as a prosthetic. It’s just a robotic prototype from the IRIM lab at the Korea University of Technology and Education. Still, this kind of research demonstrates what is possible. It proves that there are solutions to both the dexterity and durability challenges.

Wearable Biosensor Array

As you can tell from our articles on Understanding Bionic Touch, Sensory Feedback for Bionic Hands, Sensory Feedback for Bionic Feet, Advanced Neural Interfaces for Bionic Hands, and Agonist-Antagonist Myoneural Interface (AMI), we’re really interested in the subject of connecting bionic limbs to the human brain, and for good reason. Achieving this goal is the key to creating near-natural capabilities.

The Department of Electrical Engineering and Computer Sciences at UC Berkley has just added another potential component to this undertaking: wearable biosensors. Here is a short overview:

What interests us about this solution is:

  • The concept of wearing the sensors as compared to building them into a socket. It might be easier to maintain sensor contact this way.
  • The use of 64 sensors. For AI, the more data, the better!
  • All AI processing occurs on the local chip for fast adaptation.

But, as always, one must also consider the potential drawbacks:

  • Will it be comfortable to wear inside a socket?
  • How many levels of amputation will it support?
  • How accurate will it be under adverse conditions?

We will monitor this solution and report back to you when we have more information.

Non-Invasive Sensory Feedback from Bionic Feet

When we write about sensory feedback from lower-limb bionics, it is mainly about surgically implanted electrodes with all the inherent drawbacks of surgery (i.e. cost, infection, scarring, etc.).

However, with the emergence of the Agonist-Antagonist Myoneural Interface (AMI) as a means of restoring the brain’s proprioceptive sense of a lost limb at the time of amputation (as a precursor to extending this sense to a bionic replacement), we now question the need for complete lower-limb sensory feedback. With their proprioceptive sense restored, what if users just need a bit of contact feedback? And what if that feedback could be delivered via electrical stimulation of the skin, otherwise known as Transcutaneous Electrical Nerve Stimulation (TENS)?

A June 2020 paper published in the Journal of Neural Engineering examined the potential for evoking foot sensations using high-density TENS. We can’t capture the nuance of such a detailed, professional study using a few paragraphs. So, instead, we’ll try to convey the essence of it and you can click the link at the start of this paragraph for the full story.

Basically, researchers attached an electrode array to the skin above the knee at the back of the leg of each test subject.

TENS Sensory Feedback Experiment Setup

Source: Lizhi Pan et al 2020 J. Neural Eng. 17 036020

The researchers then stimulated pairs of electrodes and asked the subject to report whatever sensations they experienced. They did this for five below-the-knee test amputees and one able-bodied person, then tallied up the results across the group:

TENS Sensory Feedback Experiment Results

Source: Lizhi Pan et al 2020 J. Neural Eng. 17 036020

There was no magic bullet here, i.e. no universal response to specific points of stimulation across all subjects. But all participants did experience foot sensory feedback in response to the stimulation. This demonstrated the general feasibility of this approach.

There is a lot of follow-up work to be done on this type of solution before it can be commercialized, if ever, so why are we telling you about it? To help you plot your long-term technology roadmap. Because if AMI becomes widely available, and this type of TENS solution becomes feasible, you might want to rethink more invasive procedures.

Related Information

Are you interested in bionic limb research? If so, see our complete selection of research articles.

For a comprehensive description of all current upper-limb technologies, devices, and research, see A Complete Guide to Bionic Arms & Hands.

For a comprehensive description of all current lower-limb technologies, devices, and research, see A Complete Guide to Bionic Legs & Feet.