Figure 1: Materials, process and methodology to realize ultra flexible electronics.
From: Wafer-scale design of lightweight and transparent electronics that wraps around hairs
(a) The proposed engineered substrate consists of two soluble films (PVA and PVAc) and of a non-soluble layer (parylene) deposited on rigid or flexible support. The selective dissolution of the layers enables the release, the transfer, the adhesion and the removal after use of the electronics. The desired requirements for the layers are listed in bold. Low-temperature processable materials can be employed to fabricate ultra flexible devices in electronics and photonics. (b–e) The proposed process scheme can be implemented at wafer scale. Here, we demonstrate the feasibility of such approach in the case of a 2-inch wafer. The water starts dissolving the PVA layer from the borders of the wafer and slowly proceeds towards the centre. The whole releasing procedure takes ~30 min after which the wafer sinks while the membrane floats on water (Scale bar in b, 1 cm). (f–h) After the release of the hosting support, the membrane is fished and transferred onto flexible and elastic foils, textiles, biological tissues and implantable devices. In case of transfer to polyimide foils, nitride rubber, plant leaves and human skin, we dissolved an additional PVAc film in acetic acid to remove the electronics after use.
