This prosthetic hand brings back sensation from lost limbs

April 30, 2018

A team of researchers has developed an algorithm which can be utilized to implement uninterrupted sensation into prosthetics.

When an individual loses a limb through accidents or medical problems, it is not just the loss of functionality which can be psychologically damaging and cause adaptation issues—it is the loss of the sense of touch.

Sensations help us use our hands, feet, and limbs effectively, such as when grasping fragile objects, ascertaining how much pressure we need to apply to grip, and they also help us respond to our environments, including helping us judge how to walk on surfaces with different conditions and textures and alerting us to potentially hazardous objects.

Today’s prosthetics rarely include any feedback for users to regain their sense of touch. However, scientists from the University of Illinois have been working to change that.

On April 26, the team revealed the creation of a control algorithm which regulates electrical currents and feedbacks in prosthetics.

These currents stimulate nerves with mild electrical feedback, and together with a control algorithm, can grant prosthetics users steady feelings of sensation when in use.

The research has been published in the academic journal Science Robotics.

Some of the more advanced prosthetics on offer today do have embedded sensors which are able to stimulate nerves when the synthetic comes into contact with an object. However, the reliability of feedback based on pressure and touch is still problematic, and over time, sensors can wear away or sweat and bodily fluids can disrupt signals.

The erosion of electrodes over time can also result in electrical buildups, leading to painful shocks.

However, through the controlling algorithm embedded in a module fastened to the prosthetic, even if electrodes peel away and sweat builds up, the algorithm will make sure sensations are not disrupted—and sudden pain is no longer an issue.

The system has been tested in two patient volunteers involved in everyday tasks. The researchers found that up to 75% of electrodes can peel off before the algorithm no longer adjusts current levels effectively.

At the moment, the algorithm can only be used by attaching the control module to the outside of a prosthetic. However, the team is working on slim-lining the module so it can fit inside the object.

Cost is also an issue to tackle. Prosthetic limbs—even in the most basic forms—are often very expensive, and so implementing this technology could be problematic in anything but the most expensive models available today.

ZDNet has the full story