A 1.3-micrometre-thick elastic conductor for seamless on-skin and implantable sensors

Polydimethylsiloxane-gold conductors that are 1.3 mu m thick and have controlled morphology of microcracks in the gold film can be used to create breathable and water-resistant electrodes for recording electrocardiogram signals, as well as on-skin pressure sensors and implantable nerve electrodes. On-skin and implantable electronics require elastic conductors that are only a few micrometres thick and soft enough to form a seamless contact with three-dimensional structures. However, fabricating thin conductors that are mechanically durable and have consistent electrical properties with stretching is challenging. Here we report polydimethylsiloxane (PDMS)-gold conductors that are around 1.3 mu m thick and have a controlled morphology of microcracks in the gold film. The microcracks are formed by evaporating a 50-nm-thick gold film onto a 1.2-mu m-thick PDMS film that is supported during fabrication by a 100-mu m-thick PDMS film on glass; thermal expansion of the thick PDMS film causes the evaporated gold to form a microcracked structure on the thin PDMS. The resulting conductors can be stretched by up to 300% and remain highly conductive after strain release. We use them to create on-skin electrodes that are breathable and water resistant, and can continuously record electrocardiogram signals. We also use the conductors to create on-skin sensors with less than 3 mu m thickness that can detect small mechanical forces and create implantable nerve electrodes that can provide signal recording and stimulation.

Automated summary

Polydimethylsiloxane-gold conductors with controlled microcrack morphology in the gold film, approximately 1.3 μm thick, have been developed. These conductors can stretch up to 300% and maintain high conductivity. They can be used to create breathable and water-resistant on-skin electrodes, pressure sensors, and implantable nerve electrodes.