REHYB@TUM: Bringing back lost hand movement capabilities after stroke

06.03.2021. Functional electrical stimulation (FES) is a treatment that artificially activates muscles during exercise and activity for patients with motor disabilities. This is achieved by placing electrodes on the skin’s surface and transmitting low-energy electrical pulses through the body to induce muscle contraction in the stimulated limbs.

In the Rehyb project the researchers plan to utilize FES for the support of the hand and wrist, thus, in conjunction with the robotic exoskeleton, the final assembled result constitutes a hybrid exoskeleton system. Typically, the FES electrodes have to be placed manually to specific location, which is time-consuming for both patients and clinicians, requires expert knowledge and is error prone. However, in this project researchers from Tecnalia are developing FES array electrodes (see figure 1, left) to alleviate these issues. Here a large array of small electrode elements stimulate the muscles, thereby, enabling dynamic control of activation regions for improved selectivity and functionality.

Figure 1: [left] FES array electrodes from Tecnalia; [right] Motion capture markers for hand and finger positions

Researchers at TUM are working on developing data-driven modelling techniques to gain a precise understanding of the influence each FES element has on induced movements, hence, unlocking further potential of this technology. To this end, automated calibration routine are being investigated. The insights gained during these developments help advance approaches for human muscle system models. In addition, these research findings are crucial in empowering patients by facilitating opportunities for rehabilitation in their own homes and support during activities of daily living. The first step for these developments is enabling concurrent measurements of hand kinematics data in conjunction with stimulation by the FES system. This is accomplished by utilizing a marker-based motion capture system for the hand and wrist, which is shown in figure 1 (right). Initial experiments are conducted at the research facility of the Chair for Information-Oriented Control (ITR) at TUM (see figure 2).

Figure 2: [left] Student research intern wearing Tecnalia FES device while motion data is being captured; [right] Motion captured kinematics data (