Team 11 - Flexible Heat Sinks for Clothing Integration (ASSIST)

Our team, Flexible Heat Sinks for Clothing Integration, was tasked with designing and prototyping a flexible heat sink (HS) for use with a flexible thermoelectric generator (TEG) designed by our sponsor, ASSIST, an NSF-funded engineering research center focusing on the development of self-powered, wearable, for health and environmental monitoring. Additionally, we were tasked with determining appropriate methods of integrating the TEG and HS into a wearable garment.

A TEG is a device that uses the Seebeck effect to convert heat flux into electrical energy. Flexible TEGs are being developed to harvest thermal energy from the human body to be able to power medical or other low power wearable devices. Heat sinks are important for maintaining the temperature difference between the two sides of the TEG which keeps the TEG performing appropriately.

Our primary goals are to design a flexible heatsink that could achieve 15% of the flexibility of our sponsor’s TEG device, and improve the performance of the TEG by at least 30%. Through research our team identified several potential materials that could be used to fabricate such a product and eventually decided on using a 3D printable thermoplastic polyurethane called Ice9, produced by TCPoly of Atlanta, GA. We were attracted to the 3D printable nature of the material and its potential for rapid prototyping. Unfortunately, we eventually had to resort to having TCPoly print our designs due to difficulties printing the material ourselves.

To evaluate our heat sinks we put together and experimented with our own test methods and setups. The first thing we tested was the effect on the open circuit voltage of the TEG when our heat sinks were attached. We did this using several different setups from hotplates to heat pipes. The bench-top setup results have been promising, showing a clear ability of our heat sinks to make the system more responsive to temperature fluctuations and generate a higher TEG open circuit voltage. Eventually we plan to test the TEG and HS system on a human subject.

In alignment with our two main project goals we developed and performed a simple bend test to evaluate the flexibility of our designs. Using Image J software we captured and analyzed photos of the HS bending with varying weights applied. We then analyzed and concluded that several of our designs were able to achieve the 15% flexibility goal at an acceptable amount of applied weight.

When working with newer technology, and a research heavy project, one needs to realize that there will always be changes. Developing a new product requires a dynamic mindset and ability to ‘be flexible’ around goals, testing set ups, resource allocation, and overall information available on the subject. Team 11 learned how to roll with the punches with this project, something the whole gang is thankful for.

Register to see the students present their project here!