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Intrinsically conducting polymers (ICPs), such as polyacetylene, polyaniline, polypyrrole, polythiophene, and poly(3,4‐ethylenedioxythiophene) (PEDOT), can have important application in flexible electronics owing to their unique merits including high conductivity, high mechanical flexibility, low cost, and good biocompatibility. The requirements for their application in flexible electronics include high conductivity and appropriate mechanical properties. The conductivity of some ICPs can be enhanced through a postpolymerization treatment, the so‐called “secondary doping.” A conducting polymer film with high conductivity can be used as flexible electrode and even as flexible transparent electrode of optoelectronic devices. The application of ICPs as stretchable electrode requires high mechanical stretchability. The mechanical stretchability of ICPs can be improved through blending with a soft polymer or plasticization. Because of their good biocompatibility, ICPs can be modified as dry electrode for biopotential monitoring and neural interface. In addition, ICPs can be used as the active material of strain sensors for healthcare monitoring, and they can be adopted to monitor food processing, such as the fermentation, steaming, storage, and refreshing of starch‐based food because of the resistance variation caused by the food volume change. All these applications of ICPs are covered in this review article. Because they combine the merits of metals and plastics, intrinsically conducting polymers can have important application in flexible electronic devices and systems, such as flexible electrode particularly the transparent electrode of optoelectronic devices, stretchable electrode, dry biopotential electrode, neural interface, and strain sensors for healthcare monitoring and food processing monitoring.

Wearable dry electrodes are needed for long-term biopotential recordings but are limited by their imperfect compliance with the skin, especially during body movements and sweat secretions, resulting in high interfacial impedance and motion artifacts. Herein, we report an intrinsically conductive polymer dry electrode with excellent self-adhesiveness, stretchability, and conductivity. It shows much lower skin-contact impedance and noise in static and dynamic measurement than the current dry electrodes and standard gel electrodes, enabling to acquire high-quality electrocardiogram (ECG), electromyogram (EMG) and electroencephalogram (EEG) signals in various conditions such as dry and wet skin and during body movement. Hence, this dry electrode can be used for long-term healthcare monitoring in complex daily conditions. We further investigated the capabilities of this electrode in a clinical setting and realized its ability to detect the arrhythmia features of atrial fibrillation accurately, and quantify muscle activity during deep tendon reflex testing and contraction against resistance. Reported wearable dry electrodes have limited long-term use due to their imperfect skin compliance and high motion artifacts. Here, the authors report an intrinsically conductive, stretchable polymer dry electrode with excellent self-adhesiveness for long-term high-quality biopotential detection.

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is the most successful conducting polymer in terms of practical application. It possesses many unique properties, such as good film forming ability by versatile fabrication techniques, superior optical transparency in visible light range, high electrical conductivity, intrinsically high work function and good physical and chemical stability in air. PEDOT:PSS has wide applications in energy conversion and storage devices. This review summarizes its applications in organic solar cells, dye-sensitized solar cells, supercapacitors, fuel cells, thermoelectric devices and stretchable devices. Approaches to enhance the material/device performances are highlighted.

Solution-processed organic photovoltaic cells (OPVs) hold great promise to enable roll-to-roll printing of environmentally friendly, mechanically flexible and cost-effective photovoltaic devices. Nevertheless, many high-performing systems show best power conversion efficiencies (PCEs) with a thin active layer (thickness is ~100 nm) that is difficult to translate to roll-to-roll processing with high reproducibility. Here we report a new molecular donor, benzodithiophene terthiophene rhodanine (BTR), which exhibits good processability, nematic liquid crystalline behaviour and excellent optoelectronic properties. A maximum PCE of 9.3% is achieved under AM 1.5G solar irradiation, with fill factor reaching 77%, rarely achieved in solution-processed OPVs. Particularly promising is the fact that BTR-based devices with active layer thicknesses up to 400 nm can still afford high fill factor of ~70% and high PCE of ~8%. Together, the results suggest, with better device architectures for longer device lifetime, BTR is an ideal candidate for mass production of OPVs. There is a trade-off between increasing thickness of active layers in organic photovoltaic cells to be compatible with modern printing techniques and decreasing it to improve the device performance. Sun et al. report a nematic liquid crystalline molecular electron donor material used in thick layers.

Monitoring surgical wounds post-operatively is necessary to prevent infection, dehiscence and other complications. However, the monitoring of deep surgical sites is typically limited to indirect observations or to costly radiological investigations that often fail to detect complications before they become severe. Bioelectronic sensors could provide accurate and continuous monitoring from within the body, but the form factors of existing devices are not amenable to integration with sensitive wound tissues and to wireless data transmission. Here we show that multifilament surgical sutures functionalized with a conductive polymer and incorporating pledgets with capacitive sensors operated via radiofrequency identification can be used to monitor physicochemical states of deep surgical sites. We show in live pigs that the sutures can monitor wound integrity, gastric leakage and tissue micromotions, and in rodents that the healing outcomes are equivalent to those of medical-grade sutures. Battery-free wirelessly operated bioelectronic sutures may facilitate post-surgical monitoring in a wide range of interventions. Multifilament surgical sutures functionalized with a conductive polymer and incorporating pledgets with capacitive sensors operated via radiofrequency identification can be used to monitor physicochemical states of deep surgical sites.

Windows are one of the least energy-efficient components of a building. It allows energy to escape, leading to high cooling demand in summer and energy loss in winter. Sunlight and temperature in the building also affect people’s health, comfort, and even productivity. As a result, controlling the heat and light entering the building dynamically is critical for improving the comfort of building occupants and reducing energy consumption. In this work, we develop a tunable smart window based on transparent dielectric elastomer actuators (DEAs) as an alternative solution to sunlight and temperature control. The transparency-tuning is achieved by creating wrinkles in a soft elastomer film made of waterborne polyurethane (WPU). The actuation mechanism is based on highly transparent dielectric elastomer actuators that use all solid-state stretchable transparent conductive polymer poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)/(PEDOT:PSS/WPU) as compliant electrodes. The modulation range of the smart tunable window with direct viewing is achieved to be 35% to 90%, which is one of the largest among existing tunable windows. At the low-transparency state, the window can also effectively block the heat and decrease the temperature rise to 2°C over 200 s, while the ambient temperature rises by 6°C with direct sunlight. We anticipate that this transparency-tuning mechanism is potentially useful for privacy protection, smart glass, projector screens, displays, and camouflage. The heat isolation feature also has the potential to reduce carbon emissions and improve the sustainability of buildings and greenhouses.

Thermoelectric (TE) materials directly convert temperature gradients into electrical potential. However, conventional rigid TE materials are limited by poor mechanical compliance, potential toxicity, and non-recyclability. Here, we present an ionic TE hydrogel that addresses these challenges through high stretchability, full recyclability, and non-toxic composition. The hydrogel can be recycled through an environmentally friendly process that generates no hazardous byproducts. Our material exhibits exceptional mechanical stretchability with 1400% strain capacity, 98% optical transparency, high electrical conductivity (1.9 mS cm -1 ), and a Seebeck coefficient (−1.05 mV/K). When encapsulated in recyclable polyurethane, the resulting devices enable stable dual-mode sensing through both TE and triboelectric mechanisms, allowing simultaneous temperature and pressure detection without complex signal processing. The devices maintain 96% of their electrical performance even after recycling and self-healing cycles. This innovative hydrogel design strategy aligns with circular economy principles for environment-friendly human-machine interface applications. Thermoelectric materials can convert temperature gradients into electrical potential; however, traditional materials have unfavorable mechanical, optical, and electrical properties for devices. Here, the authors design an ionic hydrogel system optimizing these properties for human-machine interface devices.

Highlights Turning trash into treasure: The outstanding tunable aerogels were fabricated via heterodimensional by-products of silver nanowires. The first tunable form, aerogel film, shields electromagnetic interference (EMI SE > 89 dB), while the second tunable form, aerogel foam, performs dual EM functions (EMI SE > 30 dB and RL < -35 dB, EAB > 6.7 GHz). Recycle again: The secondary recycled aerogels retain nearly all of their EM protection qualities, making this closed-loop cycle desirable. One of the significant technological challenges in safeguarding electronic devices pertains to the modulation of electromagnetic (EM) wave jamming and the recycling of defensive shields. The synergistic effect of heterodimensional materials can effectively enable the manipulation of EM waves by altering the nanostructure. Here we propose a novel approach for upcycling by-products of silver nanowires that can fabricate shape-tunable aerogels which enable the modulation of its interaction with microwaves by heterodimensional structure of by-products. By-product heterodimensionality was used to design EM-wave-jamming-dissipation structures and therefore two typical tunable aerogel forms were studied. The first tunable form was aerogel film, which shielded EM interference (EMI shielding effectiveness (EMI SE) > 89 dB) and the second tunable form was foam, which performed dual EM functions (SE > 30 dB& reflective loss (RL) < -35 dB, effective absorption bandwidth (EAB) > 6.7 GHz). We show that secondary recycled aerogels retain nearly all of their EM protection properties, making this type of closed-loop cycle an appealing option. Our findings pave the way for the development of adaptive EM functions with nanoscale regulation in a green and closed-loop cycle, and they shed light on the fundamental understanding of microwave interactions with heterodimensional structures.

Stretchable, skin-interfaced, and wearable strain sensors have risen in recent years due to their wide-ranging potential applications in health-monitoring devices, human motion detection, and soft robots. High aspect ratio (AR) silver nanowires (AgNWs) have shown great potential in the flexible and stretchable strain sensors due to the high conductivity and flexibility of AgNW conductive networks. Hence, this work aims to fabricate highly stretchable, sensitive, and linear kirigami strain sensors with high AR AgNWs. The AgNW synthesis parameters and process windows have been identified by Taguchi’s design of experiment and analysis. Long AgNWs with a high AR of 1556 have been grown at optimized synthesis parameters using the one-pot modified polyol method. Kirigami sensors were fabricated via full encapsulation of AgNWs with Ecoflex silicon rubber. Kirigami-patterned strain sensors with long AgNWs show high stretchability, moderate sensitivity, excellent linearity (R2 = 0.99) up to 70% strain and can promptly detect finger movement without obvious hysteresis.

Nanostructured viruses are attractive for use as templates for ordering quantum dots to make self-assembled building blocks for next-generation electronic devices. So far, only a few types of electronic devices have been fabricated from biomolecules due to the lack of charge transport through biomolecular junctions. Here, we show a novel electronic memory effect by incorporating platinum nanoparticles into tobacco mosaic virus. The memory effect is based on conductance switching, which leads to the occurrence of bistable states with an on/off ratio larger than three orders of magnitude. The mechanism of this process is attributed to charge trapping in the nanoparticles for data storage and a tunnelling process in the high conductance state. Such hybrid bio–inorganic nanostructures show promise for applications in future nanoelectronics.