Transcutaneous Electrical Nerve Stimulation (TENS) of the Median and Radial nerve using COTS hardware (draft #1)

 JM Elek et al. described the attenuation of human wrist tremors by electrical stimulation in a paper in 1989. Recently the FDA approved a home use electrical stimulation device for the treatment of Essential Tremors (CALA Trio).  The technology behind this type of stimulation is well described and easily accessible from a large number of papers published by various authors during the past 30 years.  Having been introduced to the current generation of microcontrollers by an old acquaintance, I decided to investigate the feasibility of building an electrical stimulus device using Commercial Off The Shelf (COTS) hardware. It wasn’t a straight line path from early 2021 to this juncture.  It was an adventure in learning: both from reading and experimentation but that is a story for another time. 

Here are two photographs of my proof of concept stimulus device that I got working today, February 19, 2022.

This proof of concept test rig consists of a TENS unit I purchased from Amazon for about $100.  It has the advantage of being battery powered so it is portable and there are no dangerous voltages or currents involved.  My hand/arm tremors inspired me to deep dive into the research papers on Essential Tremors. All the online, freely accessible information, led me through a convoluted path that was littered with many interesting ideas and more than a few disappointments; "The best of the best (treatment) only works for about half of us ET sufferers!".  

Aside from the learning curve and the technical challenges, I wanted to see if it was possible to build an affordable device that was free from the substantial recurring costs of the commercial offering mentioned above.  Recurring costs are: a small amount of electricity necessary to charge the TENS unit and three round TENS self adhesive electrodes: cost about $0.50 each and they last a week or so. This "proof of concept" device is only the first step.  I have already started sourcing parts for the next version.  The control unit will be battery powered, portable, and will have a much simplified design.

The output of the TENS unit is switched between the Median nerve and the Radial nerve by a pair of Solid State Relays (SSR) seen next to my thumb.  The switching is controlled by an Arduino Mega 2690 microcontroller just above and to the left of my forefinger.  The Mega 2690 also measured the frequency of my tremors via a 3-axis gyroscope/accelerometer combo IMU mounted on a Velcro strip on the back of my hand.  Total cost was about $175 excluding taxes and shipping.

From my research, something like 40% of the ET population could benefit from this type of stimulation.  So I don’t yet know if this will attenuate my tremors in my forearm.  Whether or not I’m in that group will be discovered over the next couple of weeks of testing and adjustment.

AMA!

(Please note: This information should not be used as a substitute for medical treatment and advice. Always consult a medical professional about any health-related questions or concerns.)