MyHandSCI

Initial Motivations and Goals

When designing this device, we talked to physicians about what is particularly challenging for individuals who have limited hand movement due to SCI. The top three mentioned were:

Maintaining a hand position to perform a task
Maintaining a stronger grip
Writing with a pen/pencil

The overall idea is that patients wants to be assisted with grasping different types of everyday items. Not only for being able to grab the item, but also for maintaining a strong grip and position as needed to use the item. This is what we focused on.

Iteration 1

We started simple, testing some basic routing to be able to pull two main fingers closed.

Iteration 2

We added discrete tubing to act as bowden cables for the rope routing. This would not only help protect and guide the rope, but would also help mitigate friction. Here, the tubing spans from the wrist to the base of the finger. Finger caps are also added to attach the routing to the fingertips in order to pull the fingers shut.

Iteration 3

This iteration is very similar to the one above with the only difference being that the tubing no longer extends all the way to the base of the finger anymore. This now allows the finger to fully close without interference.

Iteration 4

This iteration takes the placements of the nodes and aims to find a better way to attach these to the finger. Instead of string tying the routing to the finger, rings are now used as guides and for placement.

Iteration 5

Several combinations of rings were tried to find the optimal one for pulling. This involved changing where on the rings the rope was routed through and observing how that changed actuation. Here are some examples:

Iteration 6

The motor was was integrated on a splint attached to the forearm. Sturdier tubes were used to be able to decrease how tubes many were needed per finger. We decided to make use of the glove itself instead of a finger cap per finger and simply attached everything to that.

Iteration 7

The tubes were swapped out for springs that ended up being more discrete on the palm and interferred less with grasping. Tubes were used past the wrist to connect to the quick disconnect fittings that lead to the motor.

Final Iteration

More closely followed normal tendon routing and added another ring back in. All the nodes now sit on natural tendon pulleys in the hand (A1, A2, A3), optimizing pulling. Pads were added to the fingertips as well to help increase grip. A sturdy thumb splint served to hold the thumb in a proper location for a pinch grasp and grasping in general.

Final Patient Results

Once we had a prototype we were happy with, we had a patient session to test out its true capabilities and get direct feedback.

Our device prototype was tested on one individual with C6 tetraplegia (affected wrist extension and paralysis in hand) using the Grasp and Release Test (GRT). The GRT assesses the ability of an individual with C5 or C6 tetraplegia to manipulate a set of objects varying in size and weight including: a peg, a weight, a fork, a block, a can, and a videotape. The participant tries to grasp and place the objects as many times as possible within a 30-second period, both with and without an assistive device, to measure how effective the device is. The objects of the GRT present two types of grasps commonly, a pinch grasp and a power grasp, so it is an appropriate proxy for common tasks an individual may need to perform in the world.

The orthosis was able to improve the participants’s GRT score from a 1 (⅙ objects successfully manipulated) to 11 (⅚ objects manipulated multiple times). This shows great promise in the device’s ability to help those affected by SCI regain some hand function.