In both artificial electronic and ionic skins, the distinction of multi-stimuli response in a single sensing unit is challenging, due to unavoidable mutual signal interference. Here, a zwitterionic skin sensor system that can continuously monitor and differentiate three-stimuli-responsive information in real-time is designed. This sandwich-structured sensor system is based on a zwitterionic thermo-glucose-sensitive skin-like hydrogel at its upper and lower layers with a middle isolation elastomer layer, enabling monitoring and distinction of temperature, mechanical and glucose information without signal interference: 1) the capacitance of the upper/lower layers as glucosetemperature-insensitive is variable to measure strain; 2) the resistance of the upper hydrogel as glucose-insensitive is variable to measure strain and temperature; and 3) the resistance of the lower hydrogel can detect three indicators. Based on the skin sensor system, a smart wound dressing is developed to pro-heal chronic diabetic wounds and enable continuous realtime monitoring of three indicators-infection, swelling, and blood glucose. This work provides a new method of real-time monitoring and the distinction of multi-stimuli response in a wearable device.

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This paper aims to elucidate the effects of exogenous brassinolide (BL) on maize germination and seedling growth under chilling stress. The cold-resistant maize hybrid Tiannong 9 and the cold-sensitive hybrid Tianhe 1 were soaked at the germination stage (6 °C) and leaves were sprayed at seedling stage (4 °C), with BL at concentrations of 0, 0.01, 0.1, and 1 mg/L. The germination rate of the maize seeds and the changes in seedling biomass, antioxidant, photosynthetic, and plant endogenous hormone systems and chloroplast ultrastructures were determined. The results showed that the optimum concentration of BL to alleviate chilling stress in maize seedlings was 0.1 mg/L. This rate effectively increased the germination rate and plant biomass of maize and significantly increased the superoxide dismutase (SOD) peroxidase (POD) and catalase (CAT) activities, the net photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (Tr), and seedling auxin (IAA), gibberellin (GA3) and trans zeatin nucleoside (t-ZR) contents under chilling stress. In addition, BL significantly reduced the malondialdehyde (MDA) content, abscisic acid (ABA) content, and intercellular carbon dioxide concentration (Ci). In the comparison of mesophyll cells, the chloroplast membrane of the treatment group was tightly attached to the stroma, and some of the plasma membranes were dissolved, but the overall structure of the chloroplast was relatively complete, and the osmiophilic granules were relatively few. The exogenous application of BL can effectively alleviate the damage caused by a low temperature in maize, maintain the normal characteristics of seedlings in chilling environments, and ensure the development and growth of plant tissue in the later stage.

Understanding the process of charge generation, transfer, and diffusion between two-dimensional (2D) materials and their supporting substrates is very important for potential applications of 2D materials. Compared with the systematic studies of triboelectric charging in a bulk sample, a fundamental understanding of the triboelectrification of the 2D material/insulator system is rather limited. Here, the charge transfer and diffusion of both the SiO surface and MoS/SiO interface through contact electrification and frictional electrification are investigated systematically in situ by scanning Kelvin probe microscopy and dual-harmonic electrostatic force microscopy. Different from the simple static charge transfer between SiO and the PtSi alloy atomic force microscope (AFM) tip, the charge transfer between the tip and the MoS/SiO system is complicated. Triboelectric charges, generated by contact or frictional electrification with the AFM tip, are trapped at the MoS/SiO interface and act as floating gates. The local charge discharge processes can be obtained by monitoring the surface potential. The charge decay time (τ) of the MoS/SiO interface is one (or two) orders of magnitude larger than the decay time τ of the SiO surface. This work facilitates an understanding of the triboelectric and de-electrification of the interface between 2D materials and substrates. In addition to the charge transfer and diffusion, we demonstrate the nanopatterns of surface and interfacial charges, which have great potential for the application of self-assembly of charged nanostructures.

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Hexagonal two-dimensional (2D) atomic crystals commonly reveal intrinsically isotropic elastic properties, but stretching or bending deformation can lead to their mechanical symmetry breaking. So far, little work has been done on strain-induced in-plane anisotropic shear behaviors of such 2D atomic crystals. Here, in theory, we predict the appearance of in-plane shear stiffness anisotropy under uniaxial normal tension strain in monolayer molybdenum disulfide. We verify experimentally such a shear characteristic based on friction-driven stretch deformation during a contact scan by employing transverse shear microscopy, and we demonstrate the visualization of anisotropic shear deformation as a function of crystallographic orientation. The present work provides deep insights into flexibility governed interactions among friction, deformation, and in-plane elastic characteristics in 2D atomic crystals.

Traditional wearable devices are commonly nonrecyclable and nondegradable, resulting in energy waste and environmental pollution. Here, a household degradable and renewable ionic skin based on edible glutinous rice gel is developed for a strain, temperature and salivary enzyme activity sensor. This gel depends on intermolecular and intramolecular Hbonds among amylopectin and amylose, and this presents excellent skin-like properties, including stretchability, self-healing property, and adhesion to various substrates. The glutinous rice gel-based skin sensor can be used to monitor vital signs and physiological parameters such as body temperature and heart rate. The sensor also achieves specific speech recognition and detects temperature and body micromovements, which provides the potential to reconstruct language or sensory/motor functions. More importantly, because of the excellent biocompatibility and degradability, the sensor can directly detect the activity of human salivary amylase, which is useful for diagnosing pancreas-, kidney-, and spleen-related diseases in the elderly. Finally, the raw material of ionic skin that originates from traditional grains is degradable and renewable as well as it can be used to prepare household wearable devices. Hence, this work not only extends the application of wearable electronics in daily life but also facilitates health monitoring in the elderly and improves their quality of life.