Passive therapy hand orthotic
Saebo, inc.
This page takes a look at my involvement in the design and engineering of an orthotic device used to treat hand/finger contracture.
Caused by stroke or other trauma, the hand/fingers can assume a permanent fist position. This is quite painful for the patient and immobilizes their hand completely.
Our device rehabilitates the hand through a method of passive therapy, gradually prying open the fingers little by little over the course of months. If worn correctly every night, the patient can expect near-full recovery in their hand.
First proposal
After initial discussions with Saebo, our first proposal set the stage for the general functionality and components of the device.
The system
The concept centers around a system of interchangeable hand plates, which the patient progresses through as they improve.These are affixed to an adjustable wrist hinge, which is supported by a forearm support cuff.
On to the details
A continuous process of refinement took us through many iterations of each and every component involved.
Physical testing
Several rounds of mockups, using a mixture of low- and high-tech prototyping, allowed us to observe firsthand some of the nuanced challenges inherent in this project.
Human factors
Not only did scores of ergonomic statistics go into our design, but so did simple humanizing details.After seeing the SLA output of our concept, I noticed the hinge dial would necessarily have tiny numeric readouts. So I devised a small magnifying dome to help out.
Wrist travel problem
Thanks to our physical mock-ups, we were able to spot this counter-intuitive problem, which significantly changed the course of our development.As the left image demonstrates, not only must the wrist be allowed to rotate, but also it must travel linearly along the axis of the forearm.
Our solution was to enable the entire hinge assembly to travel.
Refinement
Testing and cost considerations refined the design of the device, as we considered the mechanics, ergonomics, and manufacturability of each component.
Parts
This image shows an exploded view of the final proposed system, with the progressive hand plates visible red, tan, and blue.Mechanism design
This animation demonstrates my concept for a spring-loaded mechanism for affixing the hand plates.
One SKU
This image represents all the parts for one SKU of the product. The proposed system called for eight total SKUs: left- and right-handed versions in small, medium, large, and extra-large.
Final proposal
The device is currently patent-pending and should be released in 2012.All images © 2010 Saebo