Multi-Channel Functional Electrical Stimulation to Improve Specificity of Hand Extension

Area of Science:

• Biomedical Engineering
• Neurorehabilitation
• Rehabilitation Robotics

Background:

• Spinal cord injuries cause significant upper extremity paralysis, with limited adoption of functional electrical stimulation (FES) for upper limb rehabilitation compared to lower limbs.
• Current FES systems face challenges in targeting small, densely packed forearm muscles for precise hand gesture control.
• Existing 2-electrode FES setups lack the specificity and redundancy needed for complex hand movements and fatigue reduction.

Purpose of the Study:

• To develop and evaluate a novel multichannel FES system for improved specificity in upper extremity paralysis.
• To enable selective recruitment of small extrinsic hand muscles for isolated or combined activation.
• To demonstrate the system's capability in rapidly configuring FES for diverse hand gestures.

Main Methods:

• Introduction of a new multichannel FES system featuring complex current steering and high compliance voltage.
• Utilizing real-time motion capture data of the hand for FES control.
• Stimulating unique electrode configurations per second to identify hand gesture repertoires.
• Comparing a 3-active-electrode setup against traditional 2-electrode configurations.

Main Results:

• The new system successfully enabled selective recruitment of individual and combined small extrinsic hand muscles.
• Rapid identification of a rich repertoire of hand gestures was achieved through real-time configuration.
• The 3-electrode FES setup demonstrated superior specificity and redundancy compared to the 2-electrode setup.
• Potential for supporting more therapeutic motions and interleaved stimulation to reduce muscle fatigue was shown.

Conclusions:

• This research presents a significant advancement in upper-limb FES, offering greater efficiency, dexterity, and robustness.
• The developed multichannel FES system can rapidly configure stimulation to evoke various single- and multi-digit hand gestures.
• This technology holds promise for improving neurorehabilitation outcomes for individuals with spinal cord injuries and upper extremity paralysis.