Plastic can help increase the sustainability of electronic sensors

By blending polystyrene, a type of plastic, with other electronic materials, researchers at Stockholm University and KTH hope to make organic electronic devices both cheaper and more sustainable. The research is published in the scientific journal Advanced Materials.

Digital technologies have revolutionized many aspects of our everyday life – from communication to healthcare and wellbeing. Examples are our phones, but also medical devices placed on our body to measure minute changes, such as blood sugar levels. Together with these breakthroughs, increased digitalization has also led to a surge of e-waste caused by integrated materials that are durable and difficult to separate: mostly silicon and a wide range of critical raw materials including cobalt, germanium, indium, platinum, etc. 

One ongoing trend to reduce the material footprint of electronics is to decrease the amount of material invested (or wasted) in the production while, at the same time, achieve higher functionality. The researchers have shown that a blend of polymers, like polystyrene, and conjugated polymers can be used to decrease the amount of organic semiconductor in new kinds of electrochemical transistors for wearable electronics, biosensors, and medical implants.

“Organic semiconductors have the potential to decrease our dependency on critical raw materials, particularly in applications that are not meant to last for a lifetime, like disposable and consumers electronics.” says Erica Zeglio, Assistant professor and WISE fellow at the Department of Materials and Environmental Chemistry. "However, high performance organic semiconductors are currently manufactured at a small scale and using complex chemistries. Commodity polymers like polystyrene are synthesized at large scale and at a fraction of the cost."

“Blends that decrease the amount of semiconductor and increase performance are a win-win situation. We can use less amounts of the costly material component while at the same time provide better performance and stability – a critical parameter for applications, such as sensors, where reliable monitoring is of outmost importance.” says Anna Herland, Professor at KTH and co-corresponding author of this study.

“The donor-acceptor conjugated polymer p(N-T) blended with polystyrene was the most stable material and therefor my favorite, said Sebastian Buchmann during his PhD defense. He was, along with Erica Zeglio and others, one of the first user of these materials in another recent publication (Cleanroom-Free Direct Laser Micropatterning of Polymers for Organic Electrochemical Transistors in Logic Circuits and Glucose Biosensors). 

“This project was initiated by our own need to use as little amount of precious organic semiconductors as possible. We hope that these results will contribute towards cheaper and large scale development of organic semiconductors” says Erica Zeglio at Stockholm University.