Currently, there is no available needle-free approach for diabetics to monitor glucose levels in the interstitial fluid. Here, we report a path-selective, non-invasive, transdermal glucose monitoring system based on a miniaturized pixel array platform (realized either by graphene-based thin-film technology, or screen-printing). The system samples glucose from the interstitial fluid via electroosmotic extraction through individual, privileged, follicular pathways in the skin, accessible via the pixels of the array. A proof of principle using mammalian skin ex vivo is demonstrated for specific and 'quantized' glucose extraction/detection via follicular pathways, and across the hypo- to hyper-glycaemic range in humans. Furthermore, the quantification of follicular and non-follicular glucose extraction fluxes is clearly shown. In vivo continuous monitoring of interstitial fluid-borne glucose with the pixel array was able to track blood sugar in healthy human subjects. This approach paves the way to clinically relevant glucose detection in diabetics without the need for invasive, finger-stick blood sampling.

The electrochemical oxidation and re‐reduction of N′,N′,N,N‐tetrahexylphenylene diamine (THPD) deposited in form of microdroplets on a basal plane pyrolytic graphite or gold electrode is shown to be a chemically reversible process in the presence of aqueous electrolyte media containing NO3−, SCN−, ClO4−, or PF6−. Sharp voltammetric responses with a mid point potential, Emid, characteristic of the type of anion and its concentration are observed. The oxidation product, an ionic liquid, undergoes rapid ion exchange when the anion of the aqueous electrolyte is exchanged with anions of lower Emid replacing anions of higher Emid. Although the effect of the supporting electrolyte cation in the case of the alkali metals K+, Na+, and Li+ is not significant, a considerable change in the voltammetric peak shape and Emid occurs in the presence of protons. This effect, attributed to the protonation of THPD, is also sensitive to the type of anion present with anions of lower Emid causing more facile protonation. After protonation of THPD, oxidation and re‐reduction can be shown to be associated with H+ expulsion and uptake. Deposited onto the rough surface of a gold coated planoconvex quartz crystal oscillator the [THPD+ClO4−]oil deposit can be observed in form of micron‐sized droplets in SEM images. A strong frequency response of the crystal oscillator in an electrochemical quartz crystal microbalance experiment associated with the oxidation and re‐reduction of THPD can be detected but is not related to changes in mass. Rather, this frequency response may be attributed to changes in the viscosity and/or coverage of the oily deposit.

The development of smart polymer materials is reviewed and illustrated. Important examples of these polymers include conducting polymers, ionic gels, stimulus-response be used polymers, liquid crystalline polymers and piezoelectric materials, which have desirable properties for use in wearable sensors. This review outlines the mode of action in these types of smart polymers systems for utilisation as wearable sensors. Categories of wearable sensors are considered as tattoo-like designs, patch-like, textile-based, and contact lens-based sensors. The advantages and disadvantages of each sensor types are considered together with information on the typical performance. The research gap linking smart polymer materials to wearable sensors with integrated power systems is highlighted. Smart polymer systems may be used as part of a holistic approach to improve wearable devices and accelerate the integration of wearable sensors and power systems, particularly in health care.

We report the use of the alkaline-earth (Ae) metalcatalyzed dehydrocoupling of silanes and amines for the synthesis of ferrocene-containing polycarbosilazanes. The barium complex [Ba(N(SiMe 3 ) 2 ) 2 •(THF) 2 ] catalyzed the dehydrocoupling of the hydrosilane FeCp(CpSiPhH 2 ) (1) with 1,4-(H 2 NCH 2 ) 2 C 6 H 4 under mild conditions to give a polycarbosilazane with pendant ferrocene groups. The polymer could be readily cross-linked by the addition of phenylsilane to the unquenched reaction mixture. Welldefined polycarbosilazanes with ferrocene in the main chain were also obtained from the dehydrocoupling of hydrosilanes Fe(Cp-(SiPhH 2 )) 2 (3) and Fe(Cp(SiMe 2 H)) 2 (IX) with 1,4-(H(Me)-NCH 2 ) 2 C 6 H 4 and 1,4-(H 2 NCH 2 ) 2 C 6 H 4 , respectively. Crystalline monomeric analogues, FeCp(Cp(SiPh(NHBn) 2 )) (2, Bn = CH 2 (C 6 H 5 )), and Fe(Cp(SiPh(NHBn) 2 )) 2 (4), were also obtained via the dehydrocoupling benzylamine with 1 and 3, respectively. The barium-catalyzed dehydrocoupling of diaminoferrocene with Ph 2 SiH 2 or Ph(Rc)SiH 2 (6, Rc = (C 5 H 4 )Ru(C 5 H 5 )) did not result in polymer, but instead in the formation of the silazanebridged ansa-[3]ferrocenophanes (Fe(η-C 5 H 4 NH) 2 SiPh 2 ) (5) and (Fe(η-C 5 H 4 NH) 2 SiPh(Rc)) (7), respectively. Both polymeric and molecular products were electrochemically investigated, and the polymers proved to be promising precursors to magnetic iron-containing ceramics in yields of up to 64%.

Microhole fluidic ionic diodes based on asymmetric deposits of charged ionomer membranes (e. g. Nafion or polymers of intrinsic microporosity) on microhole supports yield high rectification ratios for ionic transport. They are fabricated without the need for complex micro‐ or nanostructuring, and show potential for future applications in desalination and biosensing. Here, we propose an explanation for the functional principle for this type of materials‐based ionic diode. A predictive computational model for ionic diode switching is based on finite element analysis. It is employed to determine the influence of diode geometry as well as type and concentration of aqueous electrolyte on the rectification behavior.

Nicked-based metal−organic framework-derived carbon (Ni/MOFDC) and its acid-treated counterpart (AT-Ni/ MOFDC) have been prepared as supports for palladium nanoparticle electrocatalysts (Pd/Ni/MOFDC and Pd/AT-Ni/MOFDC). These materials have been prepared using facile microwave-assisted techniques. Several spectroscopic and microscopic techniques (such as FTIR, Raman, PXRD, XPS, XANES, FT-EXAFS, and TEM) have been used to thoroughly characterize physicochemical properties of the materials. It is revealed that acid treatment successfully cleaned the metallic Ni surface of the passivating hydroxides (Ni(OH) 2 and NiOOH) to generate a very low concentration of Ni nanoparticles on the carbon support. The Ni-deficient Pd/AT-Ni/MOFDC shows excellent electrocatalytic performance toward ethanol oxidation reaction (EOR) in the alkaline medium compared to the Ni-hydroxide-rich Pd/Ni/MOFDC counterpart.As a proof-of-concept, these electrocatalysts have been employed as anodes and demonstrated for membraneless direct ethanol microfuel cells (μ-DEFCs) with a micro-3D-printed cell, with FeCo/C as electrocatalyst for the oxygen reduction reaction at the cathode. The Pd/AT-Ni/MOFDC displays increased peak power density (P m = 26.49 mW cm −2 ) with 68% voltage retention after a 24 h galvanostatic discharge test at 40 mA cm −2 and reduced impedance. The improved electrocatalytic properties of the Pd/AT-Ni/MOFDC underscore the need to clean the nickel surface of its passivating hydroxides to harness its full promotional activities toward alcohol oxidation reaction on precious metal electrocatalysts.

A highly rigid amine‐based polymer of intrinsic microporosity (PIM), prepared by a polymerization reaction involving the formation of Tröger’s base, is demonstrated to act as an ionic diode with electrolyte‐dependent bistable switchable states.

In order to prevent the microwave leakage and mutual interference, more and more microwave absorbing devices are added into the design of electronic products to ensure its routine operation. In this work, we have successfully prepared MoS2/TiO2/Ti3C2Tx hierarchical composites by one-pot hydrothermal method and focused on the relationship between structures and electromagnetic absorbing properties. Supported by comprehensive characterizations, MoS2 nanosheets were proved to be anchored on the surface and interlayer of Ti3C2Tx through a hydrothermal process. Additionally, TiO2 nanoparticles were obtained in situ. Due to these hierarchical structures, the MoS2/TiO2/Ti3C2Tx composites showed greatly enhanced microwave absorbing performance. The MoS2/TiO2/Ti3C2Tx composites exhibit a maximum reflection loss value of −33.5 dB at 10.24 GHz and the effective absorption bandwidth covers 3.1 GHz (13.9–17 GHz) at the thickness of 1.0 mm, implying the features of wide frequency and light weight. This work in the hierarchical structure of MoS2/TiO2/Ti3C2Tx composites opens a promising door to the exploration of constructing extraordinary electromagnetic wave absorbents.