Background

Over 2 million people in the United States use prosthetic limbs. However, they are worn under layers of socks, which means that they get uncomfortably hot over time. Therefore, our project aimed to engineer a product that can actively cool prosthetic liners in a compact and lightweight form factor that is durable enough for daily use.

Requirements

When beginning this project, we had some major (level 1) requirements we collectively agreed on as a group that we had to achieve. Those are, in no particular order, that our device can cool the prosthetic leg to an ambient temperature (less than 70 degrees F), that the device does not cause significant added discomfort to the user, that the device does not need to be carried in the client's hands, that the device does not break/come loose from its compartment, and that the device does not have any toxic components or parts. An image with all our requirements in a table can be seen below.

Designs/Prototypes

We had three main design ideas for this project. These were:

1. Refrigerant-Based Cooling
The refrigerant-based cooling design involves the use of a condenser and refrigerant-based cooling. Refrigerant is used to cool the foot, being pumped through tubing around the residual limb. Refrigerants, however, are mostly toxic and expensive. Furthermore, this is the largest and heaviest of our three designs. However, there are non-toxic counterparts to refrigerant that we could use in tandem with the Peltier-Based Cooling method that will be explained in further detail later. The bottom left figure shows a preliminary drawing of the refrigerant-based cooling method.

2. Radiator-Based Cooling
The radiator-based cooling design utilizes a radiator to passively cool a stream of water that flows through tubing around the prosthetic. The radiator connects to the water block, allowing it to efficiently dissipate heat. This design allows us to make a cooling attachment with a relatively small and quiet footprint, since it does not have many large parts and does not incorporate a fan. The bottom middle figure shows a preliminary drawing of the radiator-based cooling method.

3. Peltier-Based Cooling
The Peltier-Based Cooling design uses a Peltier module to cool water that flows through tubing in the prosthetic. When the Peltier module is provided with electricity, the Peltier module gets cold on one side but hot on the other, so we are cooling the hot side using a fan. The Peltier module is connected to a metallic water block to efficiently cool the water, and a small pump is used to push the now cooled water through the tubing effectively cooling the residual limb. The bottom right figure shows a preliminary drawing of the peltier-based cooling method.

Image of Current Prototype

AT Fair Poster!