Sensors integrate human and machine

Neurally-controlled prosthetic leg

Sensors integrate human and machine

This is the assessment of Max Ortiz Catalan, associate professor of medical engineering at Chalmers University of Technology in Gothenburg.

The development work, in which Swelife is funding the mechanical tests of the attachment of a new bone prosthesis, is based on the Swedish invention of osseointegrated prostheses, developed by First North-listed and Gothenburg-based medtech company Integrum AB. These prostheses are attached to the skeleton with titanium screws. This avoids the traditional cap prostheses’ painful pressure against the skin, while increasing mobility.

“This type of connection is a big step forward, but the problem of lack of control of the prosthesis remains”, says Ortiz Catalan.

He and his team are working with advanced sensors, which are to be implanted in the nerves and muscles of the leg stump and connected with the control system in the prosthesis.

Sensors interpret signals

“Even though part of a limb, for example a leg, is missing, the nerves with their connections to the brain are still there. Both our biological nerve signals and the prosthesis signals are electric. Through machine learning, the prosthesis can learn what the body’s signals mean, and vice versa. Accordingly, the signals will also return from the prosthesis to the brain and provide information – precisely in the same way as when you close your eyes; you still know exactly what angles your joints are in, whether you are touching anything, whether it is soft or hard, and so on”, he explains.

The mechanics are a challenge

The neurally-controlled prosthetic leg is the final goal for the development work that is currently underway.

“We know how to get there and, together with Integrum, we were the first in the world to succeed with prosthetic arms. At the moment, however, we are working primarily with mechanical tests. The mechanical stresses are much greater in the legs than in the arms and we are working on developing a prototype.”

Unique position on a global market

The market is global. Integrum currently has a unique position worldwide within the field of neurally-controlled prostheses in combination with osseointegration. Globally, amputation is a significant medical problem. In the USA alone, two million people are currently living with amputation and 185 000 amputations are performed every year. Even in a small country like Sweden, there are around 2600 amputations per year.

“We expect to be working with patients within two years. Then commercialisation will take another couple of years. The support we have received from Swelife is a condition to move forward with our testing. We have had a very positive and important collaboration with patients – they are very involved and interested; they are uniquely placed to see the opportunities in what we are developing.”

Updated: 14 February 2018

Text: Jörgen Olsson