The body naturally and continuously secretes sweat for thermoregulation during sedentary and routine activities at rates that can reflect underlying health conditions, including nerve damage, autonomic and metabolic disorders, and chronic stress. However, low secretion rates and evaporation pose challenges for collecting resting thermoregulatory sweat for non-invasive analysis of body physiology. Here we present wearable patches for continuous sweat monitoring at rest, using microfluidics to combat evaporation and enable selective monitoring of secretion rate. We integrate hydrophilic fillers for rapid sweat uptake into the sensing channel, reducing required sweat accumulation time towards real-time measurement. Along with sweat rate sensors, we integrate electrochemical sensors for pH, Cl−, and levodopa monitoring. We demonstrate patch functionality for dynamic sweat analysis related to routine activities, stress events, hypoglycemia-induced sweating, and Parkinson’s disease. By enabling sweat analysis compatible with sedentary, routine, and daily activities, these patches enable continuous, autonomous monitoring of body physiology at rest.

Ultrafast magnetization switching at picosecond and sub-picosecond time scales has tremendous technological potential but still poses numerous questions regarding the underlying quantum mechanical phenomena, including the roles of and interactions between the electrons, spins, and phonons (lattice). At the nanometer-scale dimensions relevant for modern applications, these phenomena become increasingly more pronounced. Until now, helicity-independent all-optical switching (HI-AOS) has been largely limited to amorphous Gd-Fe-Co alloys, for which scaling was challenging due to their relatively low anisotropies. In this work, we demonstrate HI-AOS in amorphous GdCo and scale it to nanometer dimensions while still maintaining uniform out-of-plane magnetization. Single shot HI-AOS is demonstrated in these patterned samples down to a minimum optically detectable magnetic dot size of 200 nm. The ultrafast switching behavior was also confirmed using time-resolved magneto-optic Kerr effect measurements and found to settle to its opposite magnetization state at faster rates for smaller dot diameters, passing a threshold of 75% magnetization reversal within approximately 2 ps for a 200 nm dot compared to approximately 40 ps for a 15 μm pattern. The size dependence of the ultrafast switching is explained in terms of the electron-phonon and spin-lattice interactions.

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