People with tetraplegia are often lacking grip strength, causing impairment in activities of daily living. For them, improving hand function is a priority because it is important for autonomy and participation in daily life. A tendon transfer surgery may be an option to improve the tenodesis grip, but it is an invasive procedure. Alternatively a similar effect can be produced, using a non-invasive method which can be efficient for enhancing grip strength, using a one channel research prototype with wired connections to surface electrodes. 

https://www.frontiersin.org/articles/10.3389/fnins.2020.00412/full

Important notice: This circuit has high voltages reaching 320V. It can provoke serious electric shock if not handled carefully. It is currently not ready for people without 

Disclaimer: The technology described involves the use of high-voltage stimulation, which can potentially cause physiological harm if not used with extreme caution and under the supervision of competent individuals. None of the individual contributors, system operators, developers, or sponsors can be held responsible for the outcomes or consequences of any use or attempted use of any published information.