Inkjet-printed, intrinsically stretchable conductors and interconnects

Abstract

In the future, a large variety of electronic devices will be wearable and operate in close contact with the skin. To accommodate deformations such as twisting and elongation, these devices should ideally be stretchable. One viable approach toward stretchable electronics is the development of intrinsically stretchable electronic materials, devices and circuits. Recently, the first intrinsically stretchable transistors have been demonstrated [1-7]. However, for the realization of stretchable circuits, stretchable interconnects are equally important. For the deployment of highly stretchable materials as interconnects and electrodes, patterning is crucial. Therefore, we developed a process for inkjet printing of intrinsically stretchable PEDOT:PSS-based interconnects and conductors. Ionic additives act as dopants and plasticisers in this approach [8]. A customized ink was printed on stretchable polymeric substrates (SEBS, styrene-ethylene-butadiene-styrene) and optimized to achieve a smooth morphology of the printed features by adjusting the surface tension and suppressing the coffee stain effect. The printed interconnects have a conductivity of 700 S/cm, sustain strains above 100% and show good stability in 1000-cycle stretching experiments. In addition to morphology, electrical properties and stretchability, we also investigated bias-stress stability, long-term stability in ambient air and cycling stability.