Robust, self-adhesive, reinforced polymeric nanofilms enabling gas-permeable dry electrodes for long-term application.

Robust polymeric nanofilms can be used to construct gas-permeable soft electronics that can directly adhere to soft biological tissue for continuous, long-term biosignal monitoring. However, it is challenging to fabricate gas-permeable dry electrodes that can self-adhere to the human skin and retain their functionality for long-term (>1 d) health monitoring. We have succeeded in developing an extraordinarily robust, self-adhesive, gas-permeable nanofilm with a thickness of only 95 nm. It exhibits an extremely high skin adhesion energy per unit area of 159 μJ/cm2. The nanofilm can self-adhere to the human skin by van der Waals forces alone, for 1 wk, without any adhesive materials or tapes. The nanofilm is ultradurable, and it can support liquids that are 79,000 times heavier than its own weight with a tensile stress of 7.82 MPa. The advantageous features of its thinness, self-adhesiveness, and robustness enable a gas-permeable dry electrode comprising of a nanofilm and an Au layer, resulting in a continuous monitoring of electrocardiogram signals with a high signal-to-noise ratio (34 dB) for 1 wk.