Recent advances in flexible and stretchable electronics have led to a surge of electronic skin (e-skin)-based health monitoring platforms. Conventional wireless e-skins rely on rigid integrated circuit chips that compromise the overall flexibility and consume considerable power. Chip-less wireless e-skins based on inductor-capacitor resonators are limited to mechanical sensors with low sensitivities. We report a chip-less wireless e-skin based on surface acoustic wave sensors made of freestanding ultrathin single-crystalline piezoelectric gallium nitride membranes. Surface acoustic wave-based e-skin offers highly sensitive, low-power, and long-term sensing of strain, ultraviolet light, and ion concentrations in sweat. We demonstrate weeklong monitoring of pulse. These results present routes to inexpensive and versatile low-power, high-sensitivity platforms for wireless health monitoring devices.

Recent advances in flexible and stretchable electronics have led to a surge of electronic skin (e-skin)-based health monitoring platforms. Conventional wireless e-skins rely on rigid integrated circuit chips that compromise the overall flexibility and consume considerable power. Chip-less wireless e-skins based on inductor-capacitor resonators are limited to mechanical sensors with low sensitivities. We report a chip-less wireless e-skin based on surface acoustic wave sensors made of freestanding ultrathin single-crystalline piezoelectric gallium nitride membranes. Surface acoustic wave-based e-skin offers highly sensitive, low-power, and long-term sensing of strain, ultraviolet light, and ion concentrations in sweat. We demonstrate weeklong monitoring of pulse. These results present routes to inexpensive and versatile low-power, high-sensitivity platforms for wireless health monitoring devices.

Electrocardiogram (ECG) sensor is emerging as an essential medical device for diagnosing various cardiovascular diseases in modern people. Conventional ECG sensors have investigated by several researchers, but they still have significant issues of discomfort in wearing, easy swelling, poor electrical conductivity, and signal inaccuracy. Here, we demonstrate a hydrogel nanocomposite‐based ECG sensor patches, monolithically integrated with a hydrogel‐based biocompatible electrode and an electromagnetic interference (EMI) shielding layer in a single unit. The developed device with low impedance (20 kΩ) exhibited excellent mechanical properties including adhesion force (35.8 N m −1 ), multiple detachability (5 times), stretching/twisting stability and self‐healing characteristic. The ECG sensor displayed superior long‐term humidity stability for 30 days, showing superior biocompatibility. Finally, the ECG patch with high EMI shielding property monitored human vital signal and pulse rate changes in real‐time.

A wearable health monitoring system is a promising device for opening the era of the fourth industrial revolution due to increasing interest in health among modern people. Wearable health monitoring systems were demonstrated by several researchers, but still have critical issues of low performance, inefficient and complex fabrication processes. Here, we present the world's first wearable multifunctional health monitoring system based on flash‐induced porous graphene (FPG). FPG was efficiently synthesized via flash lamp, resulting in a large area in four milliseconds. Moreover, to demonstrate the sensing performance of FPG, a wearable multifunctional health monitoring system was fabricated onto a single substrate. A carbon nanotube‐polydimethylsiloxane (CNT‐PDMS) nanocomposite electrode was successfully formed on the uneven FPG surface using screen printing. The performance of the FPG‐based wearable multifunctional health monitoring system was enhanced by the large surface area of the 3D‐porous structure FPG. Finally, the FPG‐based wearable multifunctional health monitoring system effectively detected motion, skin temperature, and sweat with a strain GF of 2564.38, a linear thermal response of 0.98 Ω °C −1 under the skin temperature range, and a low ion detection limit of 10 μ m .

Wearable and flexible sensors, capable of transducing mechanical stimuli into electrical signals, have attracted significant attention for applications, such as human motion tracking, physiological monitoring, soft robotics, electronic skin, and human-machine interfaces. In this work, we develop a polyacrylamide (PAAm)-based hybrid composite integrated with a conductive hydrogel to simultaneously enhance mechanical robustness and electrical performance for real-time motion sensing. The composite features a double-network hydrogel (DNH) composed of PAAm and sodium alginate, reinforced with MoS₂ nanosheets and ethylene glycol-doped PEDOT:PSS (DNH/MoS₂NS/EG-PEDOT:PSS), yielding a highly stretchable, adhesive, and conductive material. The adhesive layer exhibits excellent mechanical properties, including a maximum strain of over 500% and a peeling force of approximately 25 N/m, while the conductive layer maintains over 300% stretchability with significantly improved electrical conductivity. The strain sensor demonstrates a gauge factor (GF) of approximately 1.67 with excellent linearity (<i>R</i> ² ≈ 0.97), along with stable signal response over 10,000 loading/unloading cycles with minimal hysteresis. Real-time motion sensing experiments on human joints and neck movements show high fidelity, stable electrical signals, enabling the detection of subtle motions, such as speech. These results underscore the composite's strong potential for next-generation wearable sensors in healthcare monitoring, rehabilitation, and human-computer interaction systems.