Conductive hydrogels have been promising candidates for wearable and flexible electronics due to their high flexibility and biocompatibility. However, the previously reported hydrogels with conductivity over 1000 S m⁻¹ usually have poor mechanical properties including low tensile stress (<5 MPa) and toughness (<2 MJ m⁻³). Here, a liquid metal‐doped polyvinyl alcohol (PVA‐LM) hydrogel is presented, which simultaneously combines ultra‐high conductivity (maximum of 217 895 S m⁻¹) with excellent mechanical properties, including high tensile stress (15.44 MPa), large tensile strain (704%), high toughness (43.02 MJ m⁻³) and excellent fatigue resistance. Such extremely high conductivity is afforded by self‐sintering behavior of LM at the bottom surface that enables the formation of conductive networks. The formation of polymer crystalline regions and polymer‐tannic acid multiple hydrogen bonds are responsible for the impressive mechanical properties of conductive hydrogels. Particularly, the electric LM filler could be recycled in the robust hydrogel by dissociation of multiple dynamic interactions. Most importantly, wearable electrodes and capacitive sensors are developed utilizing PVA‐LM hydrogel. These devices enable accurate monitoring of bioelectrical signals and human motions, highlighting their immense potential in the realm of soft electronics and wearable technology.

Materials with programmable conductivity and stiffness offer new design opportunities for next-generation engineered systems in soft robotics and electronic devices. However, existing approaches fail to harness variable electrical and mechanical properties synergistically and lack the ability to self-respond to environmental changes. We report an electro-mechano responsive Field’s metal hybrid elastomer exhibiting variable and tunable conductivity, strain sensitivity, and stiffness. By synergistically harnessing these properties, we demonstrate two applications with over an order of magnitude performance improvement compared to state-of-the-art, including a self-triggered multiaxis compliance compensator for robotic manipulators, and a resettable, highly compact, and fast current-limiting fuse with an adjustable fusing current. We envisage that the extraordinary electromechanical properties of our hybrid elastomer will bring substantial advancements in resilient robotic systems, intelligent instruments, and flexible electronics.

In recent years, the demand for wearable strain sensors is growing due to their motion monitoring and clinical data collection capabilities. The sensors with positive piozeconductivity, i.e. their conductivity increases when stretched, are more favored in wearable electronics because they can maintain high conductivity under stretching. However, reported composites with positive piezoconductivity mostly show low sensitivity. Furthermore, few wearable electronic systems based on strain sensors are built completely with data processing capabilities. Herein, we present a wearable sensor based on a positive piezoconductive composite composed of liquid metal microdroplets, metal microparticles, and elastic matrix. The resistance of the composite is extremely high at the relaxed state but drops drastically under any deformation. It has high stretchability (fracture strain >200%) and sensitivity (gauge factor ∼100), which shows excellent performance in detecting human motions such as joint bending. Based on this composite, we demonstrate a wearable and portable sign language communication device with a fully programmable and configurable system to help people with language disabilities communicate effectively with others from the visual and auditory perspectives. By bending the fingers, the device can type words or sentences on screen and speak relevant letters through the audio.

Flexible pressure sensors based on polymer elastomers filled with conductive fillers show great advantages in their applications in flexible electronic devices. However, integratable high-sensitivity pressure sensors remain understudied. This work improves the conductivity and sensitivity of PDMS-Fe/Ni piezoresistive composites by introducing silver flakes and magnetic-assisted alignment techniques. As secondary fillers, silver flakes with high aspect ratios enhance the conductive percolation network in composites. Meanwhile, a magnetic field aligns ferromagnetic particles to further improve the conductivity and sensitivity of composites. The resistivity of the composite decreases sharply by 1000 times within a tiny compression strain of 1%, indicating excellent sensing performance. On the basis of this, we demonstrate an integratable miniature pressure sensor with a small size (2 × 2 × 1 mm), high sensitivity (0.966 kPa⁻¹), and wide sensing range (200 kPa). Finally, we develop a flexible E-skin system with 5 × 5 integratable sensor units to detect pressure distribution, which shows rapid real-time response, high resolution, and high sensitivity.

Acoustic metamaterials are capable of generating bandgaps at specific frequency ranges, which makes them have good applications in the field of vibration isolation. The bandgaps can be further broadened with active control, nonlinear components and graded structures, such as: controllable stiffness by magnetorheological elastomer (MRE) and graded stiffness. However, the current approaches to reducing the bandgaps have limitations. Both the reduction in structural stiffness and the increase in mass will reduce the overall stability of the acoustic metamaterial. In this research, a novel inerter-based acoustic metamaterial MRE isolator (IAM-MREI) was designed and prototyped to lower the bandgap. Inerters can generate a large equivalent mass with very light weight. Moreover, it is discovered that elements containing quadratic frequency terms are added to the dispersion matrix of the IAM-MREI due to the frequency-independent force applied to the resonators, which is generated by the inerters. By this way, the bandgap calculated by this dispersion matrix is greatly lowered and broadened, which cannot be achieved only with extra equivalent mass. The effects of the inerters on the overall performance of the IAM-MREI was thoroughly investigated and validated both theoretically and experimentally. The evaluation experiments confirmed that the IAM-MREI possesses a low-frequency bandgap and can provide great vibration isolation performance.