Fig. 3: Wearable powering.
From: Microbial biofilms for electricity generation from water evaporation and power to wearables
a Open-circuit voltage Vo (gray) and short-circuit current Isc (red) from biofilm devices placed on deionized water, 0.5 M NaCl, 0.5 M KCl, and artificial seawater (475.7 mM NaCl, 10.8 mM CaCl2, 25.6 mM MgCl2‧6H2O, 28.2 mM MgSO4) solutions. b A biofilm device was patched on the skin (top) and removed 18 h later (bottom). Scale bars, 0.5 cm. c Vo (gray) and Isc (red) from biofilm devices patched on sweating skin (top) and dry skin (bottom), before (left) and after (right) 18 h. d (Left) schematic of connecting biofilm devices to wearable sensors for wearable powering. (Right) Actual photos of powering a skin-wearable strain sensor with one biofilm device (top) and an electrochemical glucose sensor with three biofilm devices (bottom). Scale bars, 1 cm. e Measured pulse signal (left) from the wrist and respiration signal (right) from the chest using the biofilm-powered strain sensor. f Amperometric responses from a biofilm-powered glucose sensor placed in solutions having glucose concentrations (C) of 0, 100, 200, and 300 µM, respectively. The inset shows the calibrated response curve. g (Top) A continuous measurement of current from a biofilm-powered glucose sensor during exercise. (Bottom) Calibrated glucose levels from collected measurements before (blue) and after (orange) a meal. All the error bars are standard deviations.
