What makes the printed sensors so unique?
Neugschwender: The option of printing different printing pastes based on different materials on top of each other produces layering systems that create new mechanical properties. Apart from weight reduction and low production costs, perhaps the most important new property is the flexibility of the sensor technology. We take advantage of this feature to reinvent medical electrodes for electrocardiography (to record the heart's electrical activity) and electromyography (to record the electrical activity in muscles). At this point, the electrodes are attached manually to the skin, connected with cables, and cannot be used over a long period. We have enhanced these electrodes to where they can easily be integrated into second-skin fit sportswear. For the first time ever, our sensors facilitate the integration of these measurement methods into everyday life, thereby tracking muscle activity just by wearing clothes and making the process more transparent. The textile electrodes generate identical measurement results and differ only in the nature of the electronic system. Users feel like wearing a regular T-shirt. The technology does not impede movement.
Things started while you were at the Munich University of Applied Sciences. How did you come up with the idea and what were your first steps in developing the technology?
Neugschwender: I had issues with my back for years. I was frustrated with the discomfort, which motivated me to learn more about the causes of back pain. My studies in “Print and Media Technology” taught me about printing technology, which prompted the idea of developing printed biosensor technology for the comprehensive analysis of muscular back pain.
In a first step, we asked Professor Moosheimer for help. He is a Professor for Printing Technology and Organic Electronics who provided a feasibility assessment and effective implementation tips at the start of our journey. We subsequently conferred with other experts and various institutes and research facilities in the field of electromyography and printed electronics to ensure our development represents the current state-of-the-art.
We closely collaborated with Professor Moosheimer, printed the first sensors and characterized the key influencing factors at the beginning of January 2021. The measurement results were promising, but the sensors still required further optimization as it pertained to their flexibility, robustness, and production stability.
We ran a series of tests with different layer-based systems of newly developed pastes. Simultaneously, we worked on a substrate-independent printing process, enabling us to not only print the sensors on textiles, but also on other surfaces such as prosthetics or apply the technology as a tattoo on skin.
Our current challenge pertains to contact – that being the interface between the flexible and printed electronics and conventional electronics. Various solutions have been developed for this, which we will test extensively in the coming months.