ABSTRACT
Moisture barriers are essential for ionic sensors because moisture has a direct impact on the stability and reliability of electrochemical properties. So far, stretchable moisture barriers that can maximize the advantage of using deformable ion gel as the active material have been rarely investigated and remain as a technological challenge. This study proposes a four-layer (4L) stretchable moisture barrier alternatively composed of a poly(styrene-isobutylene-styrene) copolymer (SiBS) film (2 µm in thickness) and a eutectic gallium-indium liquid metal (LM) film (1 µm in thickness). This multilayer barrier has a low water permeability of 9.09 × 10-20 m2/Pa s at 50% uniaxial strain (ε) and retains the barrier properties at repeated stretchable cycles at ε = 50%. This study demonstrates a skin-attached precise ion gel-based temperature sensor that is independent of moisture change (even dipping in water) and body motions.
ABSTRACT
Deformable printed electronic array devices are expected to revolutionize next-generation electronics. However, although remarkable technological advances in printable inks and deformable electronic array devices have recently been achieved, technical challenges remain to commercialize these technologies. In this review article a brief introduction to printing methods highlighting significant research studies on ink formation for conductors, semiconductors, and insulators is provided, and the structural design and successful printing strategies of deformable electronic array devices are described. Successful device demonstrations are presented in the applications of passive- and active-matrix array devices. Finally, perspectives and technological challenges to be achieved are pointed out to print practically available deformable devices.
ABSTRACT
Conductive and stretchable electrodes that can be printed directly on a stretchable substrate have drawn extensive attention for wearable electronics and electronic skins. Printable inks that contain liquid metal are strong candidates for these applications, but the insulating oxide skin that forms around the liquid metal particles limits their conductivity. This study reveals that hydrogen doping introduced by ultrasonication in the presence of aliphatic polymers makes the oxide skin highly conductive and deformable. X-ray photoelectron spectroscopy and atom probe tomography confirmed the hydrogen doping, and first-principles calculations were used to rationalize the obtained conductivity. The printed circuit lines show a metallic conductivity (25,000 S cm-1), excellent electromechanical decoupling at a 500% uniaxial stretching, mechanical resistance to scratches and long-term stability in wide ranges of temperature and humidity. The self-passivation of the printed lines allows the direct printing of three-dimensional circuit lines and double-layer planar coils that are used as stretchable inductive strain sensors.
