No abstract

Contemporary cardiac and heart rate monitoring devices capture physiological signals using optical and electrode-based sensors. However, these devices generally lack the form factor and mechanical flexibility necessary for use in ambulatory and home environments. Here, we report an ultrathin (~1 mm average thickness) and highly flexible wearable cardiac sensor (WiSP) designed to be minimal in cost (disposable), light weight (1.2 g), water resistant, and capable of wireless energy harvesting. Theoretical analyses of system-level bending mechanics show the advantages of WiSP's flexible electronics, soft encapsulation layers and bioadhesives, enabling intimate skin coupling. A clinical feasibility study conducted in atrial fibrillation patients demonstrates that the WiSP device effectively measures cardiac signals matching the Holter monitor, and is more comfortable. WiSP's physical attributes and performance results demonstrate its utility for monitoring cardiac signals during daily activity, exertion and sleep, with implications for home-based care.

Reaction of guaiacol (o-methoxyphenol) in supercritical water at densities of 0 < pw < 0.7 g/cm3 and with added salts at pw = 0.50 g/cm3 showed its hydrolysis to catechol (o-hydroxyphenol) and methanol to be through a polar transition state. Correlation of the reaction kinetics following a modified Herbrandson analysis provided a quantitative summary of the greater polarity of the hydrolysis transition state relative to the hydrolysis reactants as Vzmhm ~^wm^wm " VGm<5Gm = 190 ± 20 (cm^cal/mol2)1/2. Salt addition at pw = 0.5 g/cm3 further shifted the transition-state equilibrium toward the transition-state species. A sodium chloride loading of 0.71 mmol/cm3 led to an "effective water density" of pWieff =1.1 g/cm3.Supercritical fluid (SCF) solvents have attracted considerable interest in separation processes because, near Tc