Development and Usability Testing of a Finger Grip Enhancer for the Elderly

As people age, their finger function deteriorates due to muscle, nerve, and brain degeneration. While exercises might delay this deterioration, an invention that enhances elderly people’s pinching abilities is essential. This study aims to design and develop a finger grip enhancer that facilitates the day-to-day pinching activities of elderly people. This research is an extension of a previous study that conceptualised a finger grip enhancer. The device facilitates finger flexion on the thumb and index finger, and weighs 520 g, allowing for improved portability and sufficient force exertion (13.9 N) for day-to-day pinching. To test for usability, eleven subjects aged 65 years and above performed a pinch-lift-hold test on various household objects. The pinch force before and after utilising the device was measured. Using Minitab 18, the statistical significance of using this device was analysed with a paired-samples t-test. With this device, the elderly people’s pinching abilities significantly improved in both pinch force and pinch force steadiness (p < 0.05). The proposed device has the potential to enhance elderly people’s quality of life by supporting a firm pinch in the handling of everyday objects. This research has applicational value in developing exoskeleton devices for patients who require rehabilitation.

I Want to Control Your Move: Human-Human Interface (HHI) Neuromuscular Electrical Stimulator (NMES)

Neuromuscular electrical stimulation (NMES) has been widely used in rehabilitation hubs to restore or replace the motor function of individuals who have upper neuron damage such as stroke and spinal cord injury. However, the utilization of sensors in NMES is limited and results in the lack of data for upper limb movement analysis. The proposed system implemented NMES integrated with human-to-human interface (HHI) in the rehabilitation process for stroke patients. The therapist (controller) can coach the motion of patients (subject) by injecting his own signal for patients to follow. Ten (10) subjects were tested with five (5) repeating trials. The EMG value was extracted from the finger flexion and extension at the controller side, then injected into the control unit for further stimulation of the subject. In order to evaluate the repeating motion by the subject, an accelerometer was attached to the finger. Performance evaluation of the subject was executed by comparing the flexion angle with the controller side. The result showed that the error of the system was less than 10.29 % for the first trial and gradually reduced to 1 % after 5 trials.

Changes in Cortical Activity in Stroke Survivors Undergoing Botulinum Neurotoxin Therapy for Treatment of Focal Spasticity

Background: Botulinum NeuroToxin-A (BoNT-A) relieves muscle spasticity and increases range of motion necessary for stroke rehabilitation. Determining the effects of BoNT-A therapy on brain neuroplasticity could help physicians customize its use and predict its outcome.Objective: The purpose of this study was to investigate the effects of Botulinum Toxin-A therapy for treatment of focal spasticity on brain activation and functional connectivity.Design: We used functional Magnetic Resonance Imaging (fMRI) to track changes in blood oxygen-level dependent (BOLD) activation and functional connectivity associated with BoNT-A therapy in nine chronic stroke participants, and eight age-matched controls. Scans were acquired before BoNT-A injections (W0) and 6 weeks after the injections (W6). The task fMRI scan consisted of a block design of alternating mass finger flexion and extension. The voxel-level changes in BOLD activation, and pairwise changes in functional connectivity were analyzed for BoNT-A treatment (stroke W0 vs. W6).Results: BoNT-A injection therapy resulted in significant increases in brain activation in the contralesional premotor cortex, cingulate gyrus, thalamus, superior cerebellum, and in the ipsilesional sensory integration area. Lastly, cerebellar connectivity correlated with the Fugl-Meyer assessment of motor impairment before injection, while premotor connectivity correlated with the Fugl-Meyer score after injection.Conclusion: BoNT-A therapy for treatment of focal spasticity resulted in increased brain activation in areas associated with motor control, and cerebellar connectivity correlated with motor impairment before injection. These results suggest that neuroplastic effects might take place in response to improvements in focal spasticity.

Modeling and Evaluation of a Novel Hybrid-Driven Compliant Hand Exoskeleton Based on Human-Machine Coupling Model

This paper presents the modeling design method for a novel hybrid-driven compliant hand exoskeleton based on the human-machine coupling model for the patients who have requirements on training and assisting. Firstly, the human-machine coupling model is established based on the kinematics characteristics of human fingers and the Bernoulli beam formula. On this basis, the variable stiffness flexible hinge (VSFH) is used to drive the finger extension and the cable-driven mechanism is used to implement the movement of the finger flexion. Here, a hand orthosis is designed in the proposed hand exoskeleton to act as the base and maintain the function position of the hand for patients with hand dysfunction. Then, a final design prototype is fabricated to evaluate the proposed modeling method. In the end, a series of experiments based on the prototype is proceeded to evaluate its capabilities on stretching force for extension, bio-imitability, finger flexion capability, and fingertip force. The results show that the prototype has a significant improvement in all aspects of the ability mentioned above, and has good bionics. The proposed design method can be utilized to implement the rapid design of the hybrid-driven compliant hand exoskeleton with the changed requirements. The novel modeling method can be easily applied in personalized design in rehabilitation engineering.

Multi-Link Magnet Device with Electromagnetic Manipulation System for Assisting Finger Movements with Wireless Operation

We introduce a new mechanism and control system for wireless assistive finger training. The proposed mechanism and control system can provide natural finger flexion and extension via magnetic force and torque between a driving coil and a multi-link magnetic assist device placed on the fingers. The proposed mechanism is designed to allow normal movement while maintaining a natural finger shape, even when multiple magnets are applied to the fingers. Anatomical features were considered in the design to accommodate the angular changes between the fingers during hand extension and flexion. The magnetic force between the control system and the device on the hand allows extension and flexion of the fingers without the use of wires and electrical motors. The performance of the driving system and the magnetic device were verified through various simulations and experiments. A control program with motion tracking is also developed using LabView software. Hence, a wireless assistive finger training system is successfully realized.

Interpersonal synchronization of movement intermittency

Humans manifest remarkable sensorimotor coordination abilities as showcased in the skilful performance expressed by orchestras and dance ensembles. In multi-agent interactions, sensorimotor loops that are normally involved in the control of one's own movement must accommodate also for sensory data (e.g., visual feedback) informing about others' movement to adjust performance and ultimately co-adapt to each other. Yet, a mechanistic understanding of how sensorimotor control comes into place to enable interpersonal coordination is still lacking. By examining movement intermittency, we here open a window into the dynamics of visuomotor loop control during interpersonal coordination. Specifically, we analysed submovements, i.e., recurrent (2-3 Hz) force pulses that are naturally engraved in our kinematics and deemed to reflect intrinsic intermittency in (visual-based) motor control. Participants were asked to synchronize rhythmic (0.25 Hz) finger flexion-extension movements. Besides synchronization at the common movement pace, finger velocity shows 2-3 Hz discontinuities that are consistently phase-locked between the two interacting partners. Notably, submovements alternate in a seemingly counterphase pattern, showing highest probability ~200ms before as well as after submovements generated by one's partner. Further, when the real partner is replaced by an unresponsive partner - a dot moving according to a pre-recorded human kinematics - submovements systematically follow the dot submovements, indicating that movement intermittency is causally linked between partners. These results show that submovements are actively adjusted (inter-locked) during interpersonal coordination. Visuo-motor loop dynamics of interacting individuals can thus couple to optimize synchronization of the sense-and-correct process that is required for behavioural coordination.