Ultra-conformable Organic Field-Effect Transistors and circuits for epidermal electronic applications

In this work we report the development of electronic circuits based on low voltage Organic Field-Effect Transistors (OFETs), entirely fabricated on polymer nanosheets acting as sub-micrometric substrates. The overall thickness of the proposed circuits (including the substrate, a 400 nm-thick Parylene C nanosheet) is only 600 nm, thus making them highly flexible, ultra-conformable and light-weighted. A complete characterization of the fabricated devices is reported. Mechanical performances of the nanosheets are thoroughly discussed. Full swing complementary inverters fabricated on same substrate show low noise margins and gains up to 10. Thanks to a carefully designed self-aligned structure, these devices are characterized by a very good frequency response, with a cut-off frequency usually ranging around 100 kHz. The ultra-conformability of such nanosheets allows their transfer and adhesion on complex target surfaces, such as the human skin without a significant change in their electrical performances, representing a step forward to the realization of conformable electronics particularly suited for personal monitoring systems for healthcare and sport.