Methods and Systems for Neural Stimulation, General

STABLE Project

15. February 2021

Tremor is an involuntary, rhythmic muscle contraction leading to shaking movements and thus affecting daily life activities. Often people relate tremor with Parkinson’s disease. However, the cause of shaking body parts may be the result of other diseases or disorders like essential tremor, cerebellar, physiological, or psychogenic tremor. Over 22 million people worldwide are affected.

Suppressing Tremor to A Bearable LEvel

The goal of the STABLE project is to develop a wrist/forearm brace to help people in their daily life. On the one hand the wearable should provide a stabilizing effect while on the other hand voluntary movement should not be affected by de device.

Brace model with suppression module. Source: STIL

Therefore, one key element is the separation of the movement signal into a tremulous and a voluntary part. This can be done by analyzing the signal in the frequency domain. The tremor frequency can slowly change in time but will remain in a range between 3 and 8 Hz. Voluntary motion on the other hand lies mostly below 2Hz.

Frequency analysis over time of a typical tremulous motion signal. The red line indicates the tremor frequency (peak values). Low-frequency content correspond to voluntary motion. At the back the red graph shows the motion over time. On the left the yellow graph shows an FFT analysis over the entire motion signal.

We at the IM2 institute are developing an algorithm that first separates the voluntary from the tremulous part and in a second stage fits these signals into mathematical models. With the obtained signal characteristics, the brace can be tuned accordingly and achieve a maximal tremor suppression.

The project was initiated by the company STIL (NL) whose goal is to provide accessible noninvasive wearable devices to instantly suppress tremor. Other partners involved in the project are the Fraunhofer IBMT (DE) and Senetics healthcare group (DE) forming a trinational cooperation.

Funds were obtained from eurostars, an international funding program for SMEs together with their swiss partner Innosuisse.

Frédéric Bourgeois

Research Associate


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