Research

The Neuromechanics Lab focuses on the control and neuromechanical properties of the upper extremity after a central or a peripheral injury, such as a stroke or an amputation.  Specifically, we focus on the following three research topics regarding the upper extremity neuromuscular system: the neural aspect, the mechanical aspect, and the applied aspect with a focus on rehabilitation.

Neural aspect (Muscle activation patterns)

We use high-density grid electrodes to estimate the muscle activation patterns (including gross muscle activation and individual motor unit activation), across muscles groups and across compartments of a muscle.

HD EMG grid on the extensor digitorum muscle, and individual motor unit action potentials with energy distribution

 

We develop different electrical stimulation techniques to understand muscle activation through reflex or direct motor nerve activation.  We also develop multi-modal sensing and feedback mechanisms that can influence the control of muscle activation or the control of robotic devices.

Selective haptic sensations elicited through electrical stimulation of the median and ulnar nerves

Mechanical aspect (mechanics of joint and muscle)

We use mechanical perturbations to probe the overall stiffness properties of the joint and the muscle-tendon unit.  In addition, we use different tissue imaging techniques (e.g., Ultrasound and Magnetic Resonance elastography) to quantify detailed tissue structural properties of the muscle and the tendon.

Reconstructed 3D ultrasound elastography of the biceps brachii muscle

Rehabilitation

Based on the grid electrode techniques, we use robotic assistance combined with electrical stimulation to improve upper extremity function, including reaching, grasping, and object manipulations, in stroke survivors.

We also develop different closed-loop control schemes of prosthetic arms, in order to realize intuitive and robust control under various task and environmental constraints.

Electrically elicited hand grasp patterns: power grasp, single finger flexion, handle grasp, and 3-finger pinch, etc.