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A device for measuring biological small volume liquid samples in real time is appealing. One way to achieve this is by using a microwave sensor based on reflection measurement. A prototype sensor was manufactured from low cost printed circuit board (PCB) combined with a microfluidic channel made of polymethylsiloxane (PDMS). Such a sensor was simulated, manufactured, and tested including a vacuum powered sample delivery system with robust fluidic ports. The sensor had a broad frequency band from 150 kHz to 6 GHz with three resonance frequencies applied in sensing. As a proof of concept, the sensor was able to detect a NaCl content of 125 to 155 mmol in water, which is the typical concentration in healthy human blood plasma.

Ultimately soft electronics seek affordable and high mechanical performance universal self‐healing materials that can autonomously heal in harsh environments within short times scales. As of now, such features are not found in a single material. Herein, interpenetrated elastomer network with bimodal chain length distribution showing rapid autonomous healing in universal conditions (<7200 s) with high efficiency (up to 97.6 ± 4.8%) is reported. The bimodal elastomer displays strain‐induced photoelastic effect and reinforcement which is responsible for its remarkable mechanical robustness (≈5.5 MPa stress at break and toughness ≈30 MJ m−3). The entropy‐driven elasticity allows an unprecedented shape recovery efficiency (100%) even after fracturing and 100% resiliency up to its stretching limit (≈2000% strain). The elastomers can be mechanically conditioned leading to a state where they recover their shape extremely quickly after removal of stress (nearly order of magnitude faster than pristine elastomers). As a proof of concept, universal self‐healing mechanochromic strain sensor is developed capable of operating in various environmental conditions and of changing its photonic band gap under mechanical stress. A versatile, extremely tough, and resilient universal self‐healing elastomer is achieved with bimodal interpenetrated network design. Elastomer shows a high toughness up to 30 MJ m−3 while being 100% resilient up to its stretching limit (≈2000% strain). The material shows high self‐healing efficiencies (up to 97.6 ± 4.8%) even in harsh environmental conditions including supercooled saline water (−19 °C).

Soft and stretchable electronics represents a high potential paradigm shift in field of electronics, for example, in applications related to solar cells, organic displays, electronic skin, and wearable sensors. In this work, a soft and stretchable humidity‐insensitive thermoresistive sensor is developed using interdigitated electrodes made of silver‐plated nylon fabric coated with silver‐ink and a layer of poly(3,4‐ethylenedioxythiophene)–poly(styrene sulfonate) (PEDOT: PSS) embedded into elastomer. The mechanical and thermoelectrical properties of the soft sensor are characterized and analyzed. The fabricated soft sensor provides a combination of linear temperature sensitivity of 0.46% °C −1 with an R 2 of 0.986 from 30 to 55 °C at 0% uniaxial tensile strain. It also exhibits excellent stability in environmental humidity ranging from ≈30% RH to ≈80% RH. The linear sensitivity is improved to 1.49% °C −1 by applying a 40% pre‐measurement stretch to the sensor. Due to its good temperature sensitivity (0.46 to 1.49% °C −1 ), excellent linearity (0.986), and high stretchability (≈125%), the soft and stretchable temperature sensor proves to be a very promising solution for wearable temperature sensing.

In the next generation wireless communication systems operating at near terahertz frequencies, dielectric substrates with the lowest possible permittivity and loss factor are becoming essential. In this work, highly porous (98.9% ± 0.1%) and lightweight silica foams (0.025 ± 0.005 g/cm 3 ), that have extremely low relative permittivity ( ε r = 1.018 ± 0.003 at 300 GHz) and corresponding loss factor (tan δ < 3 × 10 −4 at 300 GHz) are synthetized by a template-assisted sol-gel method. After dip-coating the slabs of foams with a thin film of cellulose nanofibers, sufficiently smooth surfaces are obtained, on which it is convenient to deposit electrically conductive planar thin films of metals important for applications in electronics and telecommunication devices. Here, micropatterns of Ag thin films are sputtered on the substrates through a shadow mask to demonstrate double split-ring resonator metamaterial structures as radio frequency filters operating in the sub-THz band.

Solution‐processable organic conductor–supramolecular elastomer blends are emerging materials for intrinsically stretchable and autonomously self‐healing organic electronics. Herein, the feasibility of a heterogenous multiphase polymer blend is demonstrated for soft, ultraflexible, self‐adhesive, and self‐healing multilayered film structures for electromagnetic interference (EMI) shielding and microwave absorber (MWA) purposes. The developed soft multilayered films achieve a 5–40 fold improvement in the thickness of the MWA compared to the current state‐of‐the‐art. The thickness normalized reflection loss (RL) is up to 65.26 dB mm−1 with 8.5 GHz bandwidth at 18–26.5 GHz. The maximum thickness normalized EMI shielding effectiveness peaks at up to 175 dB mm−1. The EMI shielding and MWA properties are maintainable up to 150% tensile strain with only a small decrease in the overall attenuation and RL. Furthermore, the developed films are capable of fully autonomously self‐healing and achieve a tough adhesion in temperatures of −30–145 °C, and underwater with maximum single‐lap shear adhesion strength of ≈481.5 kPa to soft thermoplastic polyurethane films. Thus, the developed multilayered films can be utilized for absorption‐dominant EMI shielding or MWA purposes as stretchable coatings. The developed materials also show considerable potential for emerging damage and puncture‐resistant organic soft electronics with autonomous material‐level self‐healing. Applicability of autonomously self‐healing supramolecular polymer blend is demonstrated for thin, soft, and ultraflexible microwave absorbing material structures. The developed multilayer films demonstrate excellent performance up to 150% uniaxial stretching with maximum thickness normalized  shielding effectiveness and reflection loss of ≈175 dB mm−1 and ≈65 dB mm−1, respectively, and further demonstrate autonomous self‐healability and self‐adhesiveness in wide temperature range (−30–145 °C), and under water.

Next‐generation, truly soft, and stretchable electronic circuits with material level self‐healing functionality require high‐performance solution‐processable organic conductors capable of autonomously self‐healing without external intervention. A persistent challenge is to achieve required performance level as electrical, mechanical, and self‐healing properties optimized in tandem are difficult to attain. Here heterogenous multiphase conductor with cocontinuous morphology and macroscale phase separation for ultrafast universally autonomous self‐healing with full recovery of pristine tensile and electrical properties in less than 120 and 900 s, respectively, is reported. The multiphase conductor is insensitive to flaws under stretching and achieves a synergistic combination of conductivity up to ≈1.5 S cm−1, stress at break ≈4 MPa, toughness up to >81 MJ m−3, and elastic recovery exceeding 2000% strain. Such properties are difficult to achieve simultaneously with any other type of material so far. The solution‐processable multiphase conductor offers a paradigm shift for damage tolerant and environmentally resistant soft electronic components and circuits with material level self‐healing. Ultraelastic and high‐conductivity organic conductor–elastomer blend with ultrafast and efficient self‐healing in universal conditions is demonstrated. The notch‐insensitive multiphase conductor, with a cocontinuous morphology and controllable heterogeneity, achieves synergistically optimized properties including toughness >80 MJ m−3, stress at break >4 MPa, elastic recovery >2000% strains, and conductivity up to ≈1.5 S cm−1.

Stretchable and self‐healing soft conductive materials are essential for soft electronics, robotics, wearables, and bioelectronics. However, achieving a single material that simultaneously offers high and stable conductivity, minimal resistance changes under extreme stretching, high‐resolution universal printability, autonomous self‐healing, and pressure‐sensitive adhesive properties for direct bonding of surface‐mountable components remains challenging. Here, a printable ink composed of liquid metal microparticles and carboxylic acid‐functionalized carbon nanotubes, blended into a bimodal supramolecular elastomer matrix is introduced. After photothermal activation, the material is capable of reorganizing conductive pathways and achieves a high conductivity (> 20000 S·cm−1 under strain), exceptional strain insensitivity (R/R0 < 3.95 up to 500%), and an elastic working range >700%. The reversible oxygen‐boron and hydrogen bonding enable both effective autonomous self‐healing and direct assembly of self‐healing hybrid electronic circuits and systems through self‐adhesiveness. To showcase the high performance and functionality, a highly stretchable, self‐healing, and waterproof 3 × 5 pixel display is fabricated. A printable, self‐healing, stretchable, and highly conductive ink with pressure‐activated adhesive properties is designed by incorporation of liquid metal microparticles and carboxyl‐functionalized carbon nanotubes into a bimodal supramolecular elastomer. After photothermal activation, it achieves conductivity of >20000 S·cm⁻¹, R/R₀ < 3.95 at < 500% strain, and >700% elastic working range. Demonstrated in a stretchable, self‐healing 3 × 5 pixel display with waterproofing.

Stretchable and wearable strain sensors have been intensively studied in recent years for applications in human motion monitoring. However, achieving a high-performance strain sensor with high stretchability, ultra-sensitivity, and functionality, such as tunable sensing ranges and sensitivity to various stimuli, has not yet been reported, even though such sensors have great importance for the future applications of wearable electronics. Herein, a novel and versatile strain sensor based on a cracking (silver ink patterned silicone elastomer)-(silver plated nylon structure) (Ag-DS/CF) has been designed and fabricated. The unique structure combined precisely shaped stretchable conductive fabrics and wrinkled Ag-ink pattern to achieve an excellent electrical performance. The Ag-DS/CF could be used to detect both large and subtle human motions and activities, pressure changes, and physical vibrations by achieving high stretchability up to 75%, ultrahigh sensitivity (gauge factor >10 4 –10 6 ), tunable sensing ranges (from 7 to 75%). Excellent durability was demonstrated for human motion monitoring with machine washability. The extremely versatile Ag-DS/CF showed outstanding potential for the future of wearable electronics in real-time monitoring of human health, sports performance, etc.

In this paper a piezoelectric energy harvester based on a Cymbal type structure is presented. A piezoelectric disc ∅35 mm was confined between two convex steel discs ∅35 mm acting as a force amplifier delivering stress to the PZT and protecting the harvester. Optimization was performed and generated voltage and power of the harvester were measured as functions of resistive load and applied force. At 1.19 Hz compression frequency with 24.8 N force a Cymbal type harvester with 250 μm thick steel discs delivered an average power of 0.66 mW. Maximum power densities of 1.37 mW/cm 3 and 0.31 mW/cm 3 were measured for the piezo element and the whole component, respectively. The measured power levels reported in this article are able to satisfy the demands of some monitoring electronics or extend the battery life of a portable device.

Self‐Healing Elastomers Soft electronics seek all‐around high mechanical performance universal self‐healing elastomers. In article number 2103235, Jarkko Tolvanen and co‐workers report design strategy to achieve tough and resilient universal self‐healing elastomer. The resilin‐inspired bimodal siloxane‐based elastomer benefits from combination of soft and hard phases. The cover displays existing phase‐separated morphology during shape recovery captured by optical microscopy.