Micro/Nano-Fabrication of Flexible Poly(3,4-Ethylenedioxythiophene)-Based Conductive Films for High-Performance Microdevices

Thin Polymeric Nanoparticle Membrane Coupled With Photothermal Membrane for Unprecedented Solar-Driven VOCs Removal

The removal of trace volatile organic compounds (VOCs) from water through solar-driven evaporation is crucial for ensuring access to safe drinking water. However, the faster evaporation rate of VOCs compared to water presents a significant challenge in effectively removing these hazardous compounds. To address this issue, a thin polymeric nanoparticle separation membrane is integrated with a photothermal membrane, forming a dual-layer solar evaporator. The bottom layer, a hydrogen-bonding complexed  polymer nanoparticle (HCPN) membrane, is fabricated by complexing poly(acrylic acid) and poly(vinylpyrrolidone) into well-dispersed nanoparticles through hydrogen bonding. This HCPN membrane selectively impedes VOC transport while allowing water to pass. The top layer is an in situ-grown photothermal membrane that absorbs solar energy, converting it into heat to drive the water evaporation process. Together, the two layers enable efficient separation and evaporation. This dual-layer solar evaporator demonstrates unprecedented performance, achieving a water evaporation rate of 2.18 kg m-2 h-1 under 1 sun irradiation and over 98% rejection to VOCs. The system maintains stability during 30-h continuous operation and performs effectively under real sunlight conditions. With its high efficiency, stability, and adaptability to real-world conditions, this solar evaporator offers a promising solution for providing safe, clean water in remote and underserved areas.

Fabrication of Poly(s-triazine-co-o-aminophenol) Conducting Polymer via Electropolymerization and Its Application in Aqueous Charge Storage

Designing conducting polymers with novel structures is essential for electrochemical energy storage devices. Here, copolymers of s-triazine and o-aminophenol are electropolymerized from an aqueous solution onto a carbon cloth substrate using the galvanostatic method. The poly(s-triazine-co-o-aminophenol) (PT-co-oAP) is characterized, and its charge storage properties are investigated in 1 M H2SO4 and in 1 M ZnSO4. At 1 A g-1, the specific capacities of PT-co-oAP reach 101.3 mAh g-1 and 84.4 mAh g-1 in 1 M H2SO4 and in 1 M ZnSO4, respectively. The specific capacity of PT-co-oAP maintains 90.3% of its initial value after cycling at 10 A g-1 for 2000 cycles in 1 M H2SO4. The high specific capacity achieved originates from abundant surface active sites, facile ion diffusion, with optimized active site structure achieved by forming copolymer. The charge storage mechanism involves the redox processes of amino/imino groups and hydroxyl/carbonyl groups in the copolymer, together with the insertion of cations. Two electrode devices using two PT-co-oAP and aqueous 1 M H2SO4 are assembled, and the maximum energy density reaches 63 Wh kg-1 at 0.5 A g-1 with a power density of 540 W kg-1. The capacity retention of the device after 3000 cycles at 10 A g-1 reaches 81.2%.

Impact of Electrical Stimulation on Mental Stress, Depression, and Anxiety: A Systematic Review

Individuals experiencing high levels of stress face significant impacts on their overall well-being and quality of life. Electrical stimulation techniques have emerged as promising interventions to address mental stress, depression, and anxiety. This systematic review investigates the impact of different electrical stimulation approaches on these types of disorders. The review synthesizes data from 30 studies, revealing promising findings and identifying several research gaps and challenges. The results indicate that electrical stimulation has the potential to alleviate symptoms of anxiety, depression, and tension, although the degree of efficacy varies among different patient populations and modalities. Nevertheless, the findings also underscore the necessity of standardized protocols and additional research to ascertain the most effective treatment parameters. There is also a need for integrated methodologies that combine hybrid EEG-fNIRS techniques with stress induction paradigms, the exploration of alternative stimulation modalities beyond tDCS, and the investigation of the combined effects of stimulation on stress. Despite these challenges, the growing body of evidence underscores the potential of electrical stimulation as a valuable tool to manage mental stress, depression, and anxiety, paving the way for future advancements in this field.

Decellularized Biohybrid Nerve Promotes Motor Axon Projections

Developing nerve grafts with intact mesostructures, superior conductivity, minimal immunogenicity, and improved tissue integration is essential for the treatment and restoration of neurological dysfunctions. A key factor is promoting directed axon growth into the grafts. To achieve this, biohybrid nerves are developed using decellularized rat sciatic nerve modified by in situ polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). Nine biohybrid nerves are compared with varying polymerization conditions and cycles, selecting the best candidate through material characterization. These results show that a 1:1 ratio of FeCl3 oxidant to ethylenedioxythiophene (EDOT) monomer, cycled twice, provides superior conductivity (>0.2 mS cm-1), mechanical alignment, intact mesostructures, and high compatibility with cells and blood. To test the biohybrid nerve's effectiveness in promoting motor axon growth, human Spinal Cord Spheroids (hSCSs) derived from HUES 3 Hb9:GFP cells are used, with motor axons labeled with green fluorescent protein (GFP). Seeding hSCS onto one end of the conduit allows motor axon outgrowth into the biohybrid nerve. The construct effectively promotes directed motor axon growth, which improves significantly after seeding the grafts with Schwann cells. This study presents a promising approach for reconstructing axonal tracts in humans.

PEDOT:PSS Nanoparticle Membranes for Organic Solvent Nanofiltration

Recycling of valuable solutes and recovery of organic solvents via organic solvent nanofiltration (OSN) are important for sustainable development. However, the trade-off between solvent permeability and solute rejection hampers the application of OSN membranes. To address this issue, the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) nanoparticle membrane with hierarchical pores is constructed for OSN via vacuum filtration. The small pores (the free volume of the polymer chain) charge for the solute rejection (high rejection efficiency for low molecule weight solute) and allow solvent passing while the large pores (the void between two PEDOT:PSS nanoparticles) promote the solvent transport. Owing to the lack of connectivity among the large pores, the fabricated PEDOT:PSS nanoparticle membrane enhanced solvent permeance while maintaining a high solute rejection efficiency. The optimized PEDOT:PSS membrane affords a MeOH permeance of 7.2 L m-2 h-1 bar-1 with over 90% rejection of organic dyes, food additives, and photocatalysts. Moreover, the rigidity of PEDOT endows the membrane with distinctive stability under high-pressure conditions. The membrane is used to recycle the valuable catalysts in a methanol solution for 150 h, maintaining good separation performance. Considering its high separation performance and stability, the proposed PEDOT:PSS membrane has great potential for industrial applications.

Electropolymerization of s-Triazines and Their Charge Storage Performance in Aqueous Acidic Electrolytes

Designing novel π-conjugated conductive polymers with abundant redox-active groups is a viable route to achieve high charge storage performance for aqueous energy storage devices. Electropolymerization is a powerful tool to construct conductive polymers. Here, s-triazine is, for the first time, electropolymerized in an aqueous acidic solution on carbon cloth. The polytriazine-coated carbon cloth electrode (PT/CC) exhibits a granular structure, with abundant pores. The charge storage performance is investigated, and a specific capacity of 101.4 mAh g-1 at 1 A g-1 in 1 M H2SO4 is achieved. Additionally, in 1 M ZnSO4, a specific capacity of 50.3 mAh g-1 at 1 A g-1 can be achieved by the PT/CC. The PT/CC behaves as a battery-type charge storage electrode, and the amino/imino and carbonyl/hydroxyl groups contribute to the charge storage, with cation insertion and extraction. A symmetric aqueous charge storage device assembled with two PT/CC electrodes exhibits an energy density of 12.92 Wh kg-1 and a power density of 250 W kg-1 at 1 A g-1. After 2500 cycles at 10 A g-1, the device retains a specific capacity of 83.3%. This study indicates that the PT is a potential candidate material for an aqueous energy storage device.

Tailored Polypyrrole Nanofibers as Ion-to-Electron Transduction Membranes for Wearable K+ Sensors

Conductive polymers are recognized as ideal candidates for the development of noninvasive and wearable sensors for real-time monitoring of potassium ions (K+) in sweat to ensure the health of life. However, the low ion-to-electron transduction efficiency and limited active surface area hamper the development of high-performance sensors for low-concentration K+ detection in the sweat. Herein, a wearable K+ sensor is developed by tailoring the nanostructure of polypyrrole (PPy), serving as an ion-to-electron transduction layer, for accurately and stably tracing the K+ fluctuation in human sweat. The PPy nanostructures can be tailored from nanospheres to nanofibers by controlling the supramolecular assembly process during PPy polymerization. Resultantly, the ion-to-electron transduction efficiency (17-fold increase in conductivity) and active surface area (1.3-fold enhancement) are significantly enhanced, accompanied by minimized water layer formation. The optimal PPy nanofibers-based K+ sensor achieved a high sensitivity of 62 mV decade-1, good selectivity, and solid stability. After being integrated with a temperature sensor, the manufactured wearable sensor realized accurate monitoring of K+ fluctuation in the human sweat.

A Concise Guide to Silicone-Based Spring-Roll Actuator Assembly

A spring-roll actuator is a multilayer configuration of dielectric elastomer actuators that deforms in response to an electric field. To date, all spring-roll actuators are based on acrylate dielectric elastomers (DEs), and a few can reach deformations on a par with strains observed in natural muscles. Sensitivity to temperature and humidity, as well as the slow response times of acrylates, limit the commercialisation of these actuators. In this work, we developed a spring-roll actuator using commercial silicone DEs because they allow for a broader range of processing temperature and rapid response. Electrodes were deposited on a pre-strained DE film, coated with functional organosilicone polymer composite, and rolled around a metal spring. The coating enhanced the interfacial adhesion between DE and compliant electrodes, preserving the integrity and electro-mechanical properties of the fabricated spring-roll actuator. As to performance, the silicone-based spring-roll actuator could bear 200 times its own weight and displace it by 6% at the applied electric field of 90 V/μm.