Transcutaneous electrical muscle stimulation is used in a variety of clinical applications, including as a rehabilitation tool to help people with limited mobility. It is effective for maladies such as certain types of urinary incontinence, for example, but getting the muscles of the arm to move in unison and with appropriate strength via electrical stimulation through the skin is very difficult.
Researchers at The Feinstein Institutes for Medical Research, a part of Northwell Health, a New York State healthcare network, have now developed a system that can, without relying on implants, stimulate individual fingers of quadriplegic individuals to properly grasp objects with their hands.
The technology relies on an arm wrap with an array of electrodes built-in, as well as novel closed-loop neurostimulation techniques. The system can accurately trigger multiple muscle movements, at a consistent strength, without leading to excessive fatigue in the volunteer subjects.
The arm wrap used in the research came from Myant Inc., a company based in Toronto, Canada that develops high-tech textiles.
The Feinstein researchers developed the algorithms necessary to stimulate hand muscles so that the force applied by the fingers stays even throughout the time of the grasp. This was achieved thanks to feedforward-feedback control mechanisms that can normalize the grasp in real-time and without causing unnecessary discomfort.
The two quadriplegic volunteers involved in the study demonstrated impressive finger extension, flexing, and the ability to grab onto fairly large things. This included grasping and lifting a 750 mL (fifth) water bottle, something that these individuals must have been quite excited about.
Although the technology didn’t require any implants, the researchers believe that it should be possible to combine their neurostimulation approach with brain-computer interfaces to generate considerably more nuanced and better controlled movements.
Study in Bioelectronic Medicine: Closed-loop neuromuscular electrical stimulation using feedforward-feedback control and textile electrodes to regulate grasp force in quadriplegia
Via: Feinstein Institutes