Within her Master thesis project, Grace designed in collaboration with Mithras Technology an energy-autonomous watch. Read here about her journey.
My name is Grace Kayin Cheung, I am an industrial designer from Hong Kong. I have been working with designers and studios from different backgrounds on a variety of projects, ranging from furniture to electronics. After a few years of working in said field, I have enrolled in my Master’s studies at Ecole cantonale d’art de Lausanne in Switzerland.
Since I am very interested in technologies and electronics, and since there are many different technology start-ups in Switzerland, I have decided to search for possible collaborative partners. In March 2021, I got in touch with Mithras Technology and I was so happy to join forces with them. Mithras is an ETH Zurich Spin-off that develops an alternative energy source for consumer and medtech wearables. With Mithras, wearable devices can be powered by your very own body heat. This approach fascinated me from the very beginning.
In this collaboration, I have designed the heat-sink component of Mithras’ subsystem, which is an electronic paper watch using thermoelectric technology to convert body heat into usable electricity. I would like to take this opportunity to share my design journey of this project, and give you deeper insight into the process and the concept behind it.
In the earliest stage of the collaboration, Franco, the CEO and founder of Mithras Technology, together with the head engineer Reinhard, has introduced me to their company’s work. Together, they have explained the working principle of thermoelectrics and its great potential to me. With a team of experienced and knowledgeable engineers, Mithras has already been developing the technology and was exploring possible applications. The first question to be answered in this collaboration, was how to define my role in this project.
In order to answer that, it is important to understand the essence of Mithras’ technology. They are fundamentally focused on converting body heat into electricity, which might be abstract for people to understand and to see the benefits of that. From my point of view, it is very important for a company to be able to communicate with people through their product. It was very interesting to design an everyday-use and familiar device that can showcase and demonstrate the Mithras application while promoting the company on a brand communication level.
A watch is a great device for introducing -Mithras since it is always in contact to our skin. Once I have decided on designing a watch, the second question followed, how to implement the thermoelectric generator (TEG) into the device.
The principle of a TEG is to generate electricity from the temperature difference between the two sides of the device. The bottom part collects heat, while the upper side remains cooler due to the flow of the surrounding air. Larger differences result in more energy being generated. Hence, the heat sink is essential for the cooling process. This inspired me to amplify and visualize the heat sink so it becomes the case of the watch. The visualization amplified the efficiency of the whole watch.
To maximize the heat harvesting and cooling effect, each component is playing an important role. The bottom of the case and the band are made from copper and graphene to collect as much heat as possible from the wrist. The rest of the case is made out of stainless steel, which works great as a heat sink for cooling. There are 60 fins on the heat sink which represent the minutes which overlay the e-paper display. The e-paper used, brings a nice texture to the watch while consuming a significantly low amount of energy. The organic shape of the case creates a large surface to volume ratio for greater contact with the surrounding air for improved heat dissipation.
Every element of the watch serves the same goal, to visualize and reinforce the principals of the thermoelectric technology. This watch is named “Heat-sync” due to its looks and its embodiment of body heat harvesting.
It has been a great pleasure to work with Mithras Technology and I am very thankful for their trust and support. I am also very grateful for Reinhard’s advice during this journey, which inspired me a lot and made the project more well resolved. Last but not least, I would like to express my most sincere thank you to everyone at Mithras and I eager to see various applications of this technology in the market very soon!
