Direct Ink Writing van PEDOT:PSS Aerogel voor Flexibele en Performante Thermo-elektrica

In our everyday lives, technology is becoming smaller, smarter, and more connected. From watches that track our heartbeats to sensors that monitor air quality, the so-called Internet of Things (IoT) is all around us. These devices promise to make our lives healthier, safer, and more efficient. But there's a catch: they all need power. Batteries run out, charging cables get in the way, and replacing tiny batteries hidden inside hundreds of devices is impractical, especially when the devices are in hard-to-reach places. What if our electronics could power themselves? This idea is at the heart of my research. I focus on a technology called thermoelectric energy harvesting, which converts tiny temperature differences into electricity. Imagine your smartwatch one day charging itself just from the warmth of your skin, or a sensor in a remote field running for years without a single battery change. To move toward this vision, we need materials that not only generate electricity efficiently from heat but are also flexible, lightweight, and easy to shape. Traditional thermoelectric materials are stiff and brittle, rendering them unsuitable for wearable applications. That's why I work with an organic material called PEDOT:PSS, which can be thought of as a special, conductive "plastic" that can be printed in three dimensions. In the current state of the art, three main research paths exist: (i) high-performing stretchable PEDOT:PSS dense films that achieve mechanical compliance but are not 3D-printable; (ii) 3D-printed dense PEDOT:PSS materials that offer decent performance, can be stretchable, but suffer from severe shrinkage after pritning and lack of omnidirectional printability; and (iii) PEDOT:PSS bulk aerogels, including 3D-printed (not ominidirectionally) ones, which are stretchable, lightweight and porous, but typically show low thermoelectric performance and require printing on separate substrates before integration into a device. In my PhD, I incorporated complementary advantages from these approaches by using different material formulations and production strategies, rather than uniting all benefits within a single system. I developed new material formulations and 3D printing setups that enable direct 3D printing of thermoelectric PEDOT:PSS aerogels onto stretchable final substrates. These printed aerogels retain their shape fidelity without shrinkage, are omnidirectionally printable, remain soft and stretchable, and achieve thermoelectric performance superior to non-printed PEDOT:PSS aerogels. Through optimization of ink formulations, printing parameters, and post-treatments, I explored how to balance stretchability, printability, and thermoelectric efficiency while enabling direct integration into a stretchable substrate. While the performance is not yet high enough to power devices independently, this work demonstrates a clear pathway toward that goal. The materials and techniques developed here provide a foundation for integrated, self-powered, and stretchable electronic systems, bringing us closer to a future where wearables and sensors that generate their own energy.