Developing Multi-biofunctional Polymeric Materials 

The loss of a limb can be detrimental to one’s life.  Life without a limb becomes frustrating as people try to complete simple tasks as lifting an object or walking.  As of 2008, there were 10 million people struggling with the loss of a limb, amounting to roughly 3 persons out of 2000.  Of these 10 million people, 3 million are arm amputees and of these 3 million arm amputees around 2.4 million of which 30% are below-the-elbow amputees, live in developing countries.  Many of these amputees simply can’t afford existing and highly expensive prosthetic arms. With health insurance, arm prosthetics can cost around $5,000 for a cosmetic prosthesis and over $20,000 for a prosthesis that has an operational hand.  Creating a low cost prosthetic arm that can perform simple hand functions would improve the quality of life for hundreds of thousands of people who cannot afford existing prosthetics.

 

The goal of this study is to design a low cost, below the elbow prosthetic arm for above the elbow amputees.  This arm is being designed in stages; hand design, forearm design, cup design, and joints articulation designs.  The hand will ideally be able to grasp objects without manipulation by the user and will also be able to flex the fingers so as to be able to carry objects with a handle, such as a briefcase.  The forearm and cup will be designed to interact with each other through an elbow joint that will allow 135 degrees of rotation of the forearm with respect to the cup with minimal user manipulation.  The hand will be connected to the forearm by a wrist joint will allow for 180 degrees of rotation of the hand with respect to the wrist to simulate pronation and supination.  The objective for the final prosthetic is to be able to support a 100 pound load, perform basic mechanical movements with minimal user interaction while all costing no more than $200.

 

The prosthetic is being designed using SolidWorks.  The models are made looking at several sections of the arm: beginning with the forearm and cup.  From these two designs, an elbow joint will be incorporated into the two models so that there is 135 degrees of rotation that can lock in various positions.  Next will be the modeling of the hand which will be designed in two parts so that the two parts can close around parts to grasp objects.   The wrist joint will then be designed to connect the hand and wrist while allowing 180 degrees of rotation.  The final part to examine will be the straps that hold the prosthetic to the patient.  The strap should be comfortable and able to distribute the weight of the arm evenly so as to prevent stress of the weight of the whole prosthetic on one spot of the patient and causing discomfort.  With the design completed, the next step will be to select a material to use in the manufacturing of the prosthetic and a fabrication method.  Initial plans are to create the forearm and socket from a mold and create the hand using a 3D printer.  The material selected will need to be able to withstand a 100-pound load from lifting objects as well as pose no health risks. Initial designs are shown here.