Highly Stretchable van der Waals Thin Films for Adaptable and Breathable Electronics

The integration of electronic systems with irregular, soft objects is of increasing interest for many emerging electronic applications including ubiquitous electronics for internet of things and bioelectronics intimately interacting with living organisms. The conventional electronics are typically made from hard inorganic materials cannot be easily integrated with soft biological structures due to the intrinsic mismatch in mechanical properties, permeability and environmental adaptability. Although the hard inorganic materials can be made flexible in the ultrathin membrane format, they are hardly stretchable and fundamentally incapable of forming conformal interface with irregular geometries with non-zero Gaussian curvatures due to the topological limitations. Here we I will discuss a unique design of highly stretchable van der Waals thin films (VDWTFs) for microscopically adaptable membrane electronics. Assembled from solution-processable two-dimensional (2D) nanosheets, the VDWTFs feature bond-free vdW interactions among the staggered nanosheets, with a sliding and rotation degree of freedom between neighbouring nanosheets to ensure extraordinary mechanical flexibility, stretchability, malleability and adaptability to irregular surface topographies. Additionally, the staggered nanosheet architecture features a highly interconnected percolation network of nanometre-scale channels with an excellent permeability. The freestanding VDWTFs show an excellent mechanical match with soft biological tissues, naturally adapting to microscopic topographies and directly merging with dynamically changing organisms with highly conformal interfaces, endowing living organisms with electronic functions, including leaf-gate and skin-gate VDWTF transistors. With excellent conformability and adaptability to skin textures, the skin transistors allow for high fidelity monitoring skin potentials and electrophysiological signals with excellent signal-to-noise ratio and superior immunity to motion artifacts.The VDWTFs thus define a new platform of electronic membranes readily adaptable to different form factors, and can open up exciting opportunities for many emerging electronic applications.