This week we settled on our final prototype, shown below:

Our goal is to provide a device that allows a user with a lack of muscle control and a tracheal tube to float independently, yet safely in the water. Our design features a U-shaped float tube (originally meant to be used for fly fishing in deep water, oddly enough) to provide enough flotation to support at least 245 lbs, a safety factor of 2. There is a mesh seat to provide comfortable support from beneath, which clips into a pool-noodle covered PVC pipe in the front in order to prevent the user from sliding forward and out. A chest and over the shoulder safety belt prevents the sternum and neck area from falling forward into the water. The whole thing is connected through a series of belts and straps wrapped around the float tube to anchor the seat and belt.

So, with our final prototype in hand, we began testing our design constraints (size, safety, and support) and design objectives (ease of use, comfort, durability, and cost). To test safety, we had a fellow intern place a 4 inch paper towel in the tracheal tube area and had them lean forward as far as they could in the device (and then repeated the test 20 billion times). If the paper towel remained dry, we knew that the water level remained a safe 4 inches away from the tracheal tube. We also measured the angle between the sternum and plane of the water and test the durability of our two weakest components, the buckles and the mesh.

To fully test ease of use, we are planning on teaching and then timing interns who are not members of the design team how to clip Mortimer (our testing dummy) into the device. To do this we needed to create an instructional manual and video and a PVC “lift” to simulate the lift that will be used to lower the user into the water from his wheelchair.

We’re looking forward to further testing next week, with our fellow interns and the intended user!