Non-invasive Stimulator for Remote Nerve Activation

Deep brain stimulation is an invasive medical procedure where electrodes are implanted in the brain to treat disorders like Parkinson's disease, epilepsy and obsessive-compulsive disorder. However, the invasiveness of this procedure creates numerous risks that can occur both during and after surgery. Temporal Interference is a non-invasive method that offers an alternative to DBS by manipulating electric fields in an area of the brain. This approach uses electrode-pairs that are placed on the outside of the head. Each electrode pair produces an electric field, and the area where two such fields meet will be electrically stimulated. Using this method, we will ideally achieve the same results as when using deep brain stimulation but for a larger area and without the risks of implanting  electrode in the brain. This research was dedicated to developing a non-invasive user-friendly stimulator that generates and outputs multiple waveforms for further and more specific research within this field and additional topics of neuroscience as well.

Background and Theory

Neurostimulation is a highly important field and has been researched many times before. Even further research into this topic has the potential to improve different areas of healthcare completely. Using electrode-pairs on the outside of the head instead of one on inside the brain, makes it possible to adjust the targeted area of stimulation by using what is called a phased array. This concept uses fixed point electrodes to steer an electric field. An array of electrodes can be lined up (like in the picture to the right) and the phase of the driving signals can be adjusted to change the location of the focal point.

Each electric field/signal is set at a frequency that is too high to cause neural firing (in the kHz range), and due to the constructive and destructive interference between the frequencies of the fields in the focal point, what is called a field envelope is created with a frequency Δf. The low pass filtering characteristic of the neural membrane filters out the higher frequencies so the envelope frequency Δf can electrically stimulate the region, and without affecting the overlying areas at that.