Ultrathin single-nm channels of transparent metal oxides offer unparalleled opportunities for boosting the performance of low power, multifunctional thin-film electronics. Here we report a scalable and low-temperature liquid metal printing (LMP) process for unlocking the ultrahigh mobility of 2-dimensional (2D) InOx. These continuous nanosheets are rapidly (60 cm s−1) printed over large areas (30 cm2) directly from the native oxide skin spontaneously formed on molten indium. These nanocrystalline LMP InOx films exhibit unique 2D grain morphologies leading to exceptional conductivity as deposited. Quantum confinement and low-temperature oxidative postannealing control the band structure and electronic density of states of the 2D InOx channels, yielding thin-film transistors with ultrahigh mobility (μ0 = 67 cm2 V−1s−1), excellent current saturation, and low hysteresis at temperatures down to 165 °C. This work establishes LMP 2D InOx as an ideal low-temperature transistor technology for high-performance, large area electronics such as flexible displays, active interposers, and thin-film sensors.

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2D conducting metal oxides offer unprecedented control of thin film electrostatics at the nanoscale. A scalable, rapid, and low‐cost approach is presented to printing transparent conductive oxides (TCOs) via spontaneous low‐temperature Cabrera‐Mott oxidation of compliant liquid metals. Repeating heterostructures of these 2D oxide layers are exploited to produce an exceptional, 100× increase in conductivity while simultaneously raising the visible range optical transmittance. This innovative approach employs defect modulation doping at the type I heterojunction between InOx/GaOx, exceeding the achievable performance with ITO, which is otherwise limited by poor dopant activation at low temperatures. The exceptional performance of these multilayer 2D TCO superlattices exceeds that of competing TCOs printed from sol‐gels and nanoparticles, establishing a 100× faster process to fabricate flexible inorganic electronics.

Stretchable electronics have the fundamental advantage of matching the complex geometries of the human body, providing opportunities for real-time biomechanical sensing. We report a method for high-frequency AC-enhanced resistive sensing that leverages deformable liquid metals to improve low-power detection of mechanical stimuli in wearable electronics. The fundamental mechanism of this enhancement is geometrical modulation of the skin effect, which induces current crowding at the surface of a liquid metal trace. In combination with DC sensing, this method quantitatively pinpoints mechanical modes of deformation such as stretching in-plane and compression out-of-plane that are traditionally impossible to distinguish. Here we explore this method by finite element simulations then employ it in a glove to detect hand gestures and tactile forces as well as a respiratory sensor to measure breathing. Moreover, this AC sensor uses lower power (100X) than DC sensors, enabling a new generation of energy-efficient wearables for haptics and biomedical sensing.

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