Researchers at the University of Oxford have developed a "revolutionary" hand prosthesis powered and controlled by the user's breathing.

The lightweight device claims to offer an alternative to the Bowden cable-driven body-powered prosthetics initially developed in the early 19th century. According to Evaluation of transradial body-powered prostheses using a robotic simulator, body-powered prostheses generally employ a Bowden cable to transmit the body motion and forces generated by the flexion and abduction movements at the shoulder joint to operate a mechanical terminal device.

The device was meant particularly for those too young or anatomically unsuited to an uncomfortable harness and cable system.

The new approach, which is centered around cost, maintenance, comfort, and ease of use, was published in the journal Prosthesis.

Various prosthetic options do exist, depending on the level of upper limb difference, among other factors. But little progress has been made in developing different approaches to power and control of body-powered devices compared to sophisticated externally powered prosthetics.

The most commonly-used functional upper-limb prosthesis continues to remain the cable-driven body-powered system. This, however, can be expensive to own and maintain in low-resource settings because of the costs associated with the necessary professional fitting and maintenance.

"Our breathing-powered device provides a novel prosthetic option that can be used without limiting any of the user’s body movements. It is one of the first truly new design approaches for power and control of a body-powered prosthetic since the emergence of the cable-driven system over two centuries ago," senior author Professor Jeroen Bergmann, Department of Engineering Science, University of Oxford, said in a statement.

Users power a small purpose-built Tesla turbine that can precisely control the prosthetic finger movements by regulating their breathing. This volume of air required can be achieved by young children, and the gearing in the unit determines the speed of the grasping action.

The device is cable and harness free, making it easily suitable for children and growing adolescents. Compared to other prosthetic options, only minimal maintenance and training are required.

The researchers collaborated with LimbBo, a leading UK-based charity for children with limb differences, to develop and refine the device.

Jane Hewitt, Trustee of LimbBo, said, "No two limb differences are the same, and what will help one child will not be suitable for another. Currently, there is some choice available regarding prosthetics, but there are still children who need a completely different approach. For many, their lack of an elbow joint severely limits their access to prosthetic devices, and so we welcomed the chance to be involved with Professor Jeroen Bergmann to look at different approaches. This is an exciting development for many of our children."

She added, "We welcome this research as a completely different approach to enabling our children to have the help that a prosthetic such as this would give them."

First author Dr. Vikranth H. Nagaraja, Department of Engineering Science, University of Oxford, said, "Over 40 million individuals worldwide are estimated to have limb differences – most with no access to any form of prosthetic care. Besides, upper-limb prosthetics currently available to patients are often neither affordable nor appropriate, especially in low-resource settings."

The research could be a significant step in accessible prosthetics.

Globally, the most popular upper-limb prostheses are powered by the human body. For body-powered (BP) upper-limb prostheses, control is provided by changing the tension of (Bowden) cables to open or close the terminal device. This technology has been around for centuries, and very few BP alternatives have been presented since. This paper introduces a new BP paradigm that can overcome certain limitations of the current cabled systems, such as a restricted operation space and user discomfort caused by the harness to which the cables are attached. A new breathing-powered system is introduced to give the user full control of the hand motion anywhere in space. Users can regulate their breathing, and this controllable airflow is then used to power a small Tesla turbine that can accurately control the prosthetic finger movements. The breathing-powered device provides a novel prosthetic option that can be used without limiting any of the user’s body movements. Here we prove that it is feasible to produce a functional breathing-powered prosthetic hand and show the models behind it along with a preliminary demonstration. This work creates a step-change in the potential BP options available to patients in the future.