Biocompatible Nanotransfer Printing Based on Water Bridge Formation in Hyaluronic Acid and Its Application to Smart Contact Lenses

Many conventional micropatterning and nano-patterning techniques employ toxic chemicals, rendering them nonbiocompatible and unsuited for biodevice production. Herein the formation of water bridges on the surface of hyaluronic acid (HA) films is exploited to develop a transfer-based nanopatterning method applicable to diverse structures and materials. The HA film surface, made deformable via water bridge generation, is brought into contact with a functional material and subjected to thermal treatment, which results in film shrinkage, allowing a robust pattern transfer. The proposed biocompatible method, which avoids the use of extra chemicals, enables the transfer of nanoscale, microscale, and thin-film structures as well as functional materials such as metals and metal oxides. A nanopatterned HA film is transferred onto a moisture-containing contact lens to fabricate smart contact lenses with unique optical characteristics of rationally designed optical nanopatterns. These lenses demonstrated binocular parallax-induced stereoscopy via nanoline array polarization and acted as cutoff filters, with nanodot arrays, capable of treating Irlen syndrome.11Nsciescopu

Rational surface modification of ZnO with siloxane polymers for room-temperature-operated thin-film transistor-based gas sensors

High demands for and rapid development of technologies related to the Internet of Things (IoT) call for a pertinent technological breakthrough in sensing devices to effectively detect various external stimuli or target analytes. Advanced sensing platforms utilizing thin-film transistors (TFTs) are essential for realizing cost-effective and high-performance chemical sensors. Here, it is reported that the utilization of a gas-selective layer based on polymeric chromatographic stationary phases is an unprecedented and facile method to establish simultaneously the desired gas selectivity and responsivity of ZnO thin films at room temperature. With the aid of computational studies, in-depth analysis and comparison of gas-sensing and the charge transfer mechanism between the gas and the resulting sensor devices are performed. ZnO with cyanopropylmethyl-phenylmethyl polysiloxane films provide excellent selective sensing with gas mixtures, and the achieved response to vaporized ethanol is nearly three times higher than the response of pristine ZnO at ~22 ??C and atmospheric pressure. This effective enhancement of sensing performance under ambient conditions is attained through the transition from chemisorption to physisorption based on intermolecular interactions between gas molecules and gas-selective polymers. This work demonstrates a potent yet cost-effective method to fabricate low power consumption gas sensor systems based on metal oxide TFT

MXene-enhanced beta-phase crystallization in ferroelectric porous composites for highly-sensitive dynamic force sensors

Piezoelectric polyvinylidene fluoride (PVDF) has been widely utilized in flexible and self-powered tactile sensors, which require high ferroelectricity of polar phase PVDF. Herein, we demonstrate self-powered piezoelectric e-skins with high sensitivity and broad sensing range based on 3D porous structures of MXene (Ti3C2Tx)/PVDF. MXene was used as a nucleation agent to increase the ferroelectric properties of PVDF. This was carried out considering its 2D geometry and abundant surface functional groups that facilitate intermolecular hydrogen bonding between the surface functional groups of MXene and the CH2 group of PVDF. In addition, porous structures can increase the variation in contact area and localized stress concentration in response to applied pressure. This further enhances the piezoelectric sensitivity. Owing to structural deformation and localized stress concentration, the piezoelectric sensitivity of porous MXene/PVDF e-skin is 11.9 and 1.4 nA kPa(-1) for low (< 2.5 kPa) and high (2.5-100 kPa) pressure ranges, respectively. These are 31 and 3.7 times higher, respectively, than that of planar MXene/PVDF e-skin (0.4 nA kPa(-1) for <100 kPa). In addition, porous MXene/PVDF e-skin exhibits a broad sensing range of up to 100 kPa, and stable sensing performance (5000 repetitions). Our piezoelectric porous MXene/PVDF e-skins enable the monitoring of high-frequency dynamic signals such as acoustic sound waves as well as low-frequency radial artery pulses. In particular, the detection of high-frequency vibrations from sliding friction enables our sensor array to perceive various surface textures with different roughness and moduli, as well as the spatial distribution of words embossed on surfaces. This demonstrates its substantial potential for application in wearable devices, prosthetic limbs, robotics, and healthcare monitoring devices

Dynamic multimodal holograms of conjugated organogels via dithering mask lithography

Polymeric materials have been used to realize optical systems that, through periodic variations of their structural or optical properties, interact with light-generating holographic signals. Complex holographic systems can also be dynamically controlled through exposure to external stimuli, yet they usually contain only a single type of holographic mode. Here, we report a conjugated organogel that reversibly displays three modes of holograms in a single architecture. Using dithering mask lithography, we realized two-dimensional patterns with varying cross-linking densities on a conjugated polydiacetylene. In protic solvents, the organogel contracts anisotropically to develop optical and structural heterogeneities along the third dimension, displaying holograms in the form of three-dimensional full parallax signals, both in fluorescence and bright-field microscopy imaging. In aprotic solvents, these heterogeneities diminish as organogels expand, recovering the two-dimensional periodicity to display a third hologram mode based on iridescent structural colours. Our study presents a next-generation hologram manufacturing method for multilevel encryption technologies. Periodic patterns with varying cross-linking densities are realized in conjugated polydiacetylene films, creating multiple holographic images-all dynamically responsive to exposure to various solvents-simultaneously in the same polymeric structures

Fluorinated benzothiadiazole (BT) groups as a powerful unit for high-performance electron-transporting polymers

Over the past few years, one of the most remarkable advances in the field of polymer solar cells (PSCs) has been the development of fluorinated 2,1,3-benzothiadiazole (BT)-based polymers that lack the solid working principles of previous designs, but boost the power conversion efficiency. To assess a rich data set for the influence of the fluorinated BT units on the charge-transport characteristics in organic field-effect transistors (OFETs), we synthesized two new polymers (PDPP-FBT and PDPP-2FBT ) incorporating diketopyrrolopyrrole (DPP) and either single- or double-fluorinated BT and thoroughly investigated them via a range of techniques. Unlike the small differences in the absorption properties of PDPP-FBT and its nonfluorinated analogue (PDPPBT), the introduction of doubly fluorinated BT into the polymer backbone induces a noticeable change in its optical profiles and energy levels, which results in a slightly wider bandgap and deeper HOMO for PDPP-2FBT, relative to the others. Grazing incidence X-ray diffraction (GIXD) analysis reveals that both fluorinated polymer films have long-range orders along the out-of-plane direction, and ??-?? stacking in the in-plane direction, implying semicrystalline lamellar structures with edge-on orientations in the solid state. Thanks to the strong intermolecular interactions and highly electron-deficient ??-systems driven by the inclusion of F atoms, the polymers exhibit electron mobilities of up to 0.42 and 0.30 cm2 V-1 s-1 for PDPP-FBT and PDPP-2FBT, respectively, while maintaining hole mobilities higher than 0.1 cm2 V-1 s-1. Our results highlight that the use of fluorinated BT blocks in the polymers is a promising molecular design strategy for improving electron transporting performance without sacrificing their original hole mobility values. (Figure Presented).close0