Smart switchable wetting surfaces have emerged as a prominent research hotspot in interfacial science. This paper systematically reviews the research progress of such surfaces from biomimetic design to responsive regulation. Based on wetting theoretical models, this review elaborates on the synergistic regulation mechanisms of surface roughness and chemical composition governing wetting states. This review summarizes the fabrication strategies, applicable scenarios, advantages, and limitations of templating, coating, and etching methods. For wettability switching behavior, external stimuli are classified into three main types: physical stimuli, chemical stimuli and multi-modal synergistic stimuli. Physical stimuli mainly include temperature, light, magnetic field, electric field and mechanical force, while chemical stimuli cover pH change, ion concentration and solvent environment. Furthermore, the reversible transformation mechanisms of surface chemical properties and microstructures are analyzed. In practical applications, this review concludes the typical applications of switchable wetting surfaces in oil-water separation, cell capture, microdroplet reaction and droplet manipulation. Finally, the existing challenges including slow response speed, poor mechanical stability and difficulty in large-scale fabrication are pointed out, and future research directions focusing on environmental friendliness and practical industrialization are prospected.

With the growing demand for non-enzymatic and non-invasive glucose detection methods, the development of reliable devices and detection techniques has become an urgent priority. This study proposes an innovative strategy for preparing MXene/Ni-Co bimetallic oxide composite electrodes via hydrothermal synthesis combined with high-temperature annealing, which are applied to non-enzymatic glucose detection. By combining MXene with bimetallic oxides, this strategy effectively suppresses the oxidation tendency of MXene while preserving its layered structure. Moreover, the synergistic effect of nickel-cobalt bimetals further enhances the electrochemical performance. The sensor exhibits prominent advantages, including high sensitivity (7.17 mA center dot mM- 1 center dot cm- 2), low detection limit (3 mu M), rapid response, long service life, and high specificity. Concurrently, this study achieves the goal by designing a microfluidic device capable of non-invasively extracting sweat and equipping it with a microcontroller that provides reaction conditions. Subsequently, a wearable non-enzymatic and non-invasive glucose sensor was developed, whose data can be real-time monitored via smart devices. This innovation not only offers new insights for biosensors in wearable electronic products but also significantly enhances the application potential of medical biosensors.

The increasing utilization of hyodeoxycholic acid (HDCA) additives in animal feed has created a pressing need for reliable detection methods. This study presents a novel non-enzymatic electrochemical platform for specific detection of HDCA using liquid nanocomposites from potassium-coordinated cyclodextrin metal-organic frameworks (K-CD-MOFs) immobilized on reduced graphene oxide (rGO) substrates. Employing neutral red (NR) as the probe, rGO-K-CD-MOFs@NR exhibits outstanding sensing performance with a wide linear detection range (5.0-100.0 mu M), a high sensitivity (0.10 mu A & sdot;mu M- 1), and low detection limit (1.97 mu M, S/N = 3). The sensor also demonstrates exceptional selectivity for HDCA and maintains stable performance for six months under lowtemperature storage conditions. The excellent performance originates from the synergistic effect between rGO's excellent electron transfer capability and K-CD-MOFs' unique host-guest recognition properties. This work not only provides an effective solution for HDCA monitoring in feed products but also offers a promising strategy for developing advanced electrochemical sensors for food safety and quality control applications in the animal husbandry industry.

Over the past few years, the continuous advancement of microelectronic devices has driven the demand for micro-energy storage devices. Planar micro-supercapacitors (MSCs), due to their unique structure, have attracted enormous research interest. However, the relatively low energy density of MSCs restricts their practical applications. In this context, fluorine and manganese co-doped laser-induced graphene (FMnLIG) electrodes are prepared via laser direct writing (LDW) technique. During the LDW process, the high temperature not only decomposes -CF3 groups to generate fluorine-containing gases, endowing the prepared FMnLIG with a rich pore structure, but also converts MnCl2 & sdot;4 H2O into MnOx (MnO2, Mn3O4) which is loaded on the FMnLIG. The presence of both the rich pore structure and MnOx increases the areal capacitance of FMnLIG. The areal capacitance of FMnLIG is 281.1 mF cm- 2 (@0.09 mA cm- 2), approximately twice that of the FLIG (129.1 mF cm- 2) and about 8 times that of the CLIG (36.5 mF cm- 2). Meanwhile, combined with the electrodeposition technique, the Zn@FMn5LIG//FMn5LIG microelectrode is prepared and assembled into a planar miniature zincion hybrid supercapacitor (ZHMSC). The energy density of the prepared FMn5LIG-ZHMSC is 22.45 mu Wh cm- 2 (@0.09 mA cm- 2), which is about twice that of FLIG-ZHMSC and about 102 times that of CLIG-ZHMSC. In addition, FMn5LIG-ZHMSC exhibits excellent flexibility, and there is no remarkable degradation in the electrochemical properties after repeated bending tests. This work provides new insights into preparing high performance LIG for flexible wearable electronic applications.

Layered double hydroxides (LDHs) have gained significant attention for their unique physicochemical properties, but their application in conductive hydrogels for strain-sensing still remains rarely explored due to their low electrical conductivity and poor compatibility with the hydrogel network. This study proposes an innovative strategy of preparing highly conductive and mechanically robust Li/Al-LDH reinforced polyacrylamide (PAM)/xanthan gum (XG) semi-interpenetrating network nano-conductive hydrogels (PXL) by in situ polymerization of acrylamide (AM) monomers in Li/Al-LDH colloidal solution. Li/Al-LDH exhibits high electrical conductivity and meanwhile interacts with the polymer matrix to form coordination/hydrogen bonds. The unique multi-collaborative network endows the PXL hydrogel with excellent mechanical properties (the strain at break is 2350%) and high sensing properties (the gauge factor is 4.65). As a proof of concept, an 8 × 8 sensor array and an intelligent insole are designed based on the PXL hydrogel, demonstrating the great broad prospects of PXL in medical, human-computer interaction, and flexible wearable applications. This study provides new insights for introducing highly conductive and uniformly dispersed LDHs into hydrogels for flexible wearable electronics.

Herein, an ionic hydrogel using sodium alginate (SA) toughened polyacrylamide (PAM)/gelatin semi-interpenetrating network with both high strength and high ductility for stress sensing is constructed. In the designed PGS-Ca2+/LiCl (short for PAM/Gelatin/SA-Ca2+/LiCl) hydrogel network, PAM acts as a flexible hydrophilic skeleton, and gelatin acts as a flexible secondary network. The addition of SA inhibits the phase separation of gelatin and improves the transparency of hydrogel. Meanwhile, the macromolecule SA complexes with metal ions of Ca2+, leading to the formation of a distinct complex structure which remarkably enhances the mechanical robustness of the hydrogel. Moreover, the incorporation of inorganic salt LiCl confers high electrical conductivity, concomitantly reducing the freezing point, mitigating water loss, and enhancing the environmental stability of the hydrogel, thereby endowing the hydrogel with improved adaptability to diverse operating conditions. PGS-Ca2+/LiCl has excellent mechanical properties and ultra-high ductility (with a tensile strength up to 110 kPa at break, a strain up to 1500

Micro-supercapacitors (MSCs) have wide application prospects in microelectronic fields such as wearable electronics due to merits of stable performance, high safety and easy integration. However, the relatively low energy density of MSCs limits their practical application. In this context, phosphorus and fluorine co-doped laserinduced graphene (FP-LIG) microelectrodes were fabricated from fluorinated polyimide containing phosphoric acid by laser direct writing (LDW) method. The introduced phosphoric acid slows down the decomposition of -CF3 during the LDW process, resulting in much more ordered and stable pores; meanwhile, phosphorus entered the graphene lattice to replace some carbon atoms, forming a C3PO structure, which not only stabilizes the interface between the electrode and the electrolyte and therefore achieves an enlarged working potential of 1.4 V, but also increases the wettability of the electrode. Using FP-3-LIG microelectrodes and PVA/H2SO4 as the gel electrolyte, the assembled FP-3-MSC demonstrates significantly enhanced energy density, delivering an energy density of 10.40 mu Wh cm(-2) (@0.09 mA cm(-2)), 2.7 times that of F-MSC and 346.7 times that of MSC. FP-3-MSC has excellent cyclic stability, displaying an areal capacitance retention rate of above 90 % after 10,000 long cycles. In addition, FP-3-MSC demonstrates excellent flexibility, indicating promising potential in the field of flexible wearable electronics.

In the MPNCs, the metal provides electrocatalytic centers for non-enzymatic glucose sensing while the conductive polymer matrix improves the dispersion and electrical conductivity of the metal nanoparticles.

Laser-induced graphene (LIG) has attracted extensive research as an electrode material for micro-supercapacitors (MSC). However, the low capacitive performance of LIG arising from both limited specific surface area and few active sites remains challenging. Herein, in situ doping of fluorine and boron atoms into laser-induced graphene was innovatively achieved via laser direct writing approach using boron-doped fluorinated polyimide (FB-PI) as the precursor. The porous fluorine and boron co-doped laser-induced graphene (FB-LIG) exhibits more active sites and improved wettability and significantly enhanced capacitive performance due to the synergistic effect of fluorine and boron co-doping. By tuning the weight ratio of boron to fluorine, the MSC utilizing FB-LIG as the electrode and poly(vinyl alcohol) (PVA)/H2SO4 as the gel electrolyte delivers a high areal capacitance of 49.81 mF/cm2 at a current density of 0.09 mA/cm2, 23 times higher that of MSC from commercial polyimide (PI)-based LIG, and 3 times that of MSC from fluorinated PI-based LIG. In addition, MSCs from FB-LIG possess excellent mechanical stability and flexibility, rendering them promising for flexible wearable microelectronics.

Strong and ductile sodium alginate (SA) reinforced polyacrylamide (PAM)/xanthan gum (XG) double network ionic hydrogels were constructed for stress sensing and self-powered wearable device applications. In the designed network of PXS-Mn+/LiCl (short for PAM/XG/SA-Mn+/LiCl, where Mn+ stands for Fe3+, Cu2+ or Zn2+), PAM acts as a flexible hydrophilic skeleton, and XG functions as a ductile second network. The macromolecule SA interacts with metal ion Mn+ to form a unique complex structure, significantly improving the mechanical strength of the hydrogel. The addition of inorganic salt LiCl endows the hydrogel with high electrical conduc-tivity, and meanwhile reduces the freezing point and prevents water loss of the hydrogel. PXS-Mn+/LiCl exhibits excellent mechanical properties and ultra-high ductility (a fracture tensile strength up to 0.65 MPa and a fracture strain up to 1800%), and high stress-sensing performance (a high GF up to 4.56 and pressure sensitivity of 0.122). Moreover, a self-powered device with a dual-power-supply mode, i.e., PXS-Mn+/LiCl-based primary battery and TENG, and a capacitor as the energy storage component was constructed, which shows promising prospects for self-powered wearable electronics.

A simple strategy is proposed to fabricate MXene@nitrogen-doped carbon (MC) composite film by vacuum filtration followed by annealing. PDA nanospheres serve as spacers, carbon precursor, and nitrogen sources, and meanwhile endow MC with porous networks. Nitrogen doping improves the electrochemical performance of MC, while the porous network increases the ion transport rate and the sensitivity to strain. When assembled into a symmetrical supercapacitor, the device delivers a high energy density of 23.2 mu Wh.cm(-2) at a power density of 317.7 mu W.cm(-2). The assembled all-solid-state zinc-ion hybrid supercapacitor delivers a much higher energy density of 61.24 mu Wh.cm(-2) at a power density of 352.76 mu W.cm(-2). The MC-based wearable sensor exhibits a sensitivity of 0.21 kPa-1 at a pressure range of 0-2 kPa for piezoresistive sensing with a superior durability over 2000 cycles. This multifunctional MC composite film has promising potentials for the fabrication of energy storage devices and wearable electronics.

Polylactic acid (PLA) has promising potentials for transient electronic applications due to its biodegradability and biocompatibility, which is expected to help alleviate electronic waste disposal problems. Recently, PLA has been used as the polymer substrate to fabricate green and flexible supercapacitors (SCs). However, the intrinsic fracture textile and limited electroactive materials deposited on the PLA substrate resulting in poor energy storage performance still remain challenging. Herein, a facile approach has been proposed to prepare flexible, yet robust electrodes of polyaniline coated on foamed PLA (PANI-fo-PLA). Aniline monomers were directly polymerized on the porous foamed PLA (fo-PLA) which was prepared via a simple nonsolvent-induced-phase-separation (NIPS) method. The fo-PLA endows the PANI-fo-PLA electrode with superior flexibility (a fracture strain of 34.70%) and high mechanical strength (a fracture strength of 77.80 MPa) which are significantly higher than those values of solvent-cast PLA films; meanwhile, the porous structure provides rich sites for the growth of PANI, which thus significantly increases the loadings of electroactive materials, and facilitates the ion transportation during the energy storage process. Employing PVA/H2SO4 as the gel electrolyte, the symmetric PANI-fo-PLA//PANI-fo-PLA SC delivers a high areal capacitance of 27.73 mF cm−2 (@0.05 mA cm−2), which is more than one hundred times higher than that of the SC based on electrodes of PANI grown on non-porous PLA film. The SC retains 66.29% of its original capacitance even bent at 90°, demonstrating its great potentials for flexible wearable electronics. Moreover, the PANI-PLA can be readily degraded in alkaline solutions within 2 h under sonication. This work paves the way to fabricate flexible, transient, and high performance energy storage devices from PLA. A flexible, robust, and degradable PANI-fo-PLA electrode with high electrochemical energy storage performance has been prepared via a both time- and energy- saving approach.

Double network (DN) conductive hydrogels have become a hotspot for wearable sensors. However, building DN hydrogel-based strain sensors with excellent mechanical strength, high sensitivity, and wide operation window still remains a challenge. This paper fabricates a high-performance strain sensor from MXene-composited polyvinyl alcohol/sodium carboxymethylcellulose (PVA/CMC) DN hydrogel which is further reinforced by tannic acid (TA). In this PCTM (short for PVA/CMC/TA/MXene hydrogel), PVA serves as the flexible backbone, CMC mainly functions as the rigid subnetwork skeleton in the hydrogel, and naturally occurring TA further enhances the mechanical properties of the hydrogel via tight hydrogen bonds between TA and the polymer chains of PVA and CMC. MXene is utilized to build the conductive path, and its abundant hydrophilic functional groups help to achieve a uniform distribution in the hydrogel, which is beneficial for achieving high sensitivity and wide operation window. The unique multiple synergetic networks of PCTM impart promising mechanical strength (a fracture tensile strength of 1.8 MPa at a fracture strain of 740%) and high sensitivity with a wide detection window (a gauge factor of 2.9 at a strain range of 0–700%) as well as long-term durability over 3000 continuous cycles. Moreover, the sensor also exhibits accurate response to different types of human motions. As a proof of concept, a PCTM sensor is fabricated for visual detection of the pressure, suggesting its promising potentials for stretchable electronic sensors.

To fabricate high performance energy storage devices with low cost, this study proposed a facile method to prepare biomass-based hierarchical activated carbon-polyaniline composites (HAC-PANI) via an in-situ chemical polymerization method, and their applications in supercapacitors (SCs) and zinc-ion hybrid supercapacitors (ZHSCs) were investigated. The results show that hierarchical porous structure and high specific area of HAC provide growth sites for PANI and effectively reduce the agglomeration of PANI; and meanwhile promote the transport of electrolyte ions, and degrease the charge transfer resistance. When the mass ratio of biomass-based hierarchical activated carbon (HAC) to aniline monomer (An) is 1∶2, uniform PANI nanoparticles were observed growing on HAC, and the resulting composite (HAC-2PANI) electrode exhibits the optimum performance. Under the three-electrode system, the mass specific capacitance of HAC-2PANI reaches as high as 415.6 F·g−1 (@1 A·g−1). The HAC-2PANI based all-solid supercapacitor (s-HAC-PANI-SC) displays a specific capacitance of 217.4 F·g−1 (@1 A·g−1), an energy density of 26.5 W·h·kg−1 and a power density of 1875.0 W·kg−1. The zinc-ion hybrid supercapacitor (HAC-PANI-ZHSC) constructed with HAC-2PANI as the cathode and zn foil as the anode exhibits a high specific capacity of 91.8 mA·h·g−1 (@0.2 A·g−1), a remarkable energy density of 64.3 W·h·kg−1, and a power density of 140.0 W·kg−1, indicating promising potentials of biomass-based carbon composites for high performance and low cost electrochemical energy storage devices.

A success has been achieved in the synthesis of dendritic core-shell copper-nickel alloy@metal oxide on nickel foam (Cu-Ni/NF) electrode for non-enzymatic glucose detection by going through a facile electrodeposition process followed by oxidation in NaOH solution. The direct electrodeposition approach facilitates the transfer of electrons in the binder-free electrode, and the dendritic structure promotes glucose diffusion while providing sufficient active sites required for the process of glucose electrocatlysis. Moreover, the unique core-shell structure promotes the catalytic activity towards glucose oxidation due to the synergistic effect caused by the bimetallic oxide shell and the metallic core that is conductive to electron transport. Accordingly, the Cu-Ni/NF electrode exhibits a high sensitivity of 11.34 mA mM-1 cm-2, a low detection limit of 2 ?M (S/N = 3), and a wide linear range of 1?600 ?M for glucose detection. In addition, the electrode demonstrates such advantages as high selectivity, fast response time, and long duration stability. The designed Cu-Ni/NF electrode shows its massive potential of application for non-enzymatic glucose detection.

Cross-linked porous starch has become a subject of research interest recently.The degree of cross-linking and the freezethaw stability are critical for cross-linked porous starch with respect to its practical applications.Herein, cross-linked porous corn starch (c-PCS) was prepared by the pre-alkalization of porous corn starch (PCS) using NaCl/NaOH which was then crosslinked using epichlorohydrin (ECH).The effects of key experimental parameters involved in both the pre-alkalization process (i.e., the mass ratio of NaOH to PCS (m NaOH /m pcs ), the mass ratio of NaCl to PCS (m NaCl /m pcs ), the temperature (T a ), and the reaction time (t a )) and the cross-linking reaction (the ratio of ECH volume to the mass of PCS (V ECH /m pcs ), the ratio of solution volume to the mass of PCS (V s /m pcs ), pH value, the temperature (T c ), and the reaction time (t c )) on the cross-linking degree and freeze-thaw stability of c-PCS were investigated in details.Results show that optimum conditions for the pre-alkalization and cross-linking reaction to obtain c-PCS are as follows: m NaCl /m pcs is 0.06, m NaOH /m pcs is 0.02, T a is 40 °C and t a is 1.0 h, V ECH /m pcs is 0.003 (mL/g), V s /m pcs is 7 (mL/g), pH is 10, T c is 20 °C, and t c is 3.0 h.The morphology, crystalline structure and thermal stability of the as-obtained c-PCS were also investigated, suggesting that the surface became rougher, the crystallinity was decreased, and the thermal stability was enhanced resulting from the cross-linking reaction.

The paper reported a facile method to prepare activated carbons (ACs) with high methylene blue (MB) adsorption capabilities via reflux-microwave-assisted activation approach. The low-cost agricultural waste corncob precursor was first refluxed in the aqueous solution of activating agents (i.e., ZnCl2 or KOH) for pretreatment, followed by microwave-assisted activation. The reflux process significantly shortens the pretreatment time to 4 h, compared to usually 24 h soaking in the traditional practice; and meanwhile greatly facilitates the diffusion of the activating agents into the precursor; whereas the microwave-assisted activation endows the ACs with hierarchical pore structures and a high specific area (e.g, 1405 m2/g for KOH pretreated AC). The ACs are also featured with rich oxygen-containing functional groups such as hydroxyl groups on the surface, and exhibit high adsorption capacity using MB as a model adsorbate because of the electrostatic interactions. Under the optimum condition (the impregnation ratio of KOH to the corncob of 2:1 (wt. %), microwave power of 600 W, and microwave time of 7 min), the prepared KAC demonstrates an adsorption capacity of as high as 636.94 mg/g. Moreover, the ACs can be readily regenerated by alkaline solution and still show satisfying adsorption performance after three times of regeneration. These findings indicate the feasibility of preparing high adsorption performance ACs by reflux-microwave-assisted activation approach.

Wearable piezoresitive sensors have exhibited promising potentials for applications in motion detection and human-computer interactions. Herein, we reported a facile sol-gel followed by hydrothermal reduction approach to prepare polypyrrole/reduced graphite oxide aerogel (PPy@rGA) film, which is more oriented to flexible wearable piezoresistive sensors as compared with traditional cylindrical reduced graphene oxide (rGO) aerogel. The strong π-π interactions between rGO and PPy enhance the interfacial strength and help to maintain the integrity of the composite aerogel film. Meanwhile, the PPy nanoparticles anchoring on the edges and defects of rGO sheets create more electrically conductive paths when an external pressure is applied, and therefore give rise to significant changes in the resistance value and thus excellent piezoresistive sensing performance. The PPy2@rGA film (pyrrole monomer: graphene oxide is 2:1 wt%)–based piezoresistive sensor exhibits a high sensitivity of 0.9 kPa −1 in a linear range that is of 0 to 1 kPa, a short response time of 165 ms, and a short relaxation time of 132 ms, and is able to withstand 10,000 cycles. Moreover, the wearable sensor is capable of detecting large as well as small human motion. This study shows the feasibility of fabricating wearable piezoresitive sensors from rGO aerogel films reinforced by intrinsically conductive polymers. Graphical abstract In this polypyrrole/reduced graphite oxide aerogel film which is more oriented to flexible wearable piezoresistive sensors, PPy nanoparticles anchor adjacent rGO sheets via strong π-π interfacial forces and meanwhile serve as nano-spacers that contribute to an enhanced piezoresistive sensing performance.