Practical applications of next-generation stretchable electronics hinge on the development of sustained power supplies to drive highly sensitive on-skin sensors and wireless transmission modules. Although the manufacture of stretchable self-charging power units has been demonstrated by integrating stretchable energy harvesters and power management circuits with energy storage units, they often suffer from low and unstable output power especially under mechanical deformation and human movements, as well as complex and expensive fabrication processes. This work presents a low-cost, scalable, and facile manufacturing approach based on laser-induced graphene foams to yield a self-powered wireless sensing platform. 3D porous foams with high specific surface area and excellent charge transport provide an efficient flow of triboelectric electrons in triboelectric nanogenerators. The surface coating or doping with second laser irradiation on these foams can also form a 3D composite to provide high energy density in micro-supercapacitor arrays. The integration of a triboelectric nanogenerator and power management circuits with micro-supercapacitor arrays can efficiently harvest intermittent mechanical energy from body movements into stable power output. 3D foams and their composites patterned into various geometries conveniently create various deformable sensors on large scale at low cost. The generated stable, yet high, power with adjustable voltage and current outputs drives various stretchable sensors and wireless transmission modules to wirelessly measure pulse, strain, temperature, electrocardiogram, blood pressure, and blood oxygen. The self-powered, wireless, wearable sensing platform paves the way to wirelessly detect clinically relevant biophysical and biochemical signals for early disease diagnostics and healthy aging.

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Magnetic hysteresis loops were measured for ferrimagnetic iron chalcogenide ${\text{Fe}}_3{\text{Se}}_4$ nanoparticles in the whole temperature range below the Curie temperature $T_C$ (315 K). The coercivity of the material is huge, reaching about 40 kOe at 10 K. The magnetic anisotropy constant K was determined from the magnetic hysteresis loop using the law of approach to saturation. The deduced anisotropy constant at 10 K is $5.22\times {10}^6 {\text{erg}/\text{cm}}^3$ , which is over one order of magnitude larger than that of ${\text{Fe}}_3{\mathrm{O}}_4$ . We also demonstrated that the experimental magnetic hysteresis loop is in good agreement with the theoretical curve calculated by Stoner and Wohlfarth for a noninteracting randomly oriented uniaxial single-domain particle system. Moreover, we show that K is proportional to the cube of the saturation magnetization $M_s$ , which confirms earlier theoretical models for uniaxial magnets.