Skin‐interfaced electrochemical sensing devices are widely developed for biochemical sensing at molecular levels. However, the sensing electrodes fabricated with photolithography or printing technique are hard to achieve high stretchability without special designs like serpentine shape. Also, most of them require wired connections with external electrochemical workstations for data acquisition or on‐board batteries to power the circuits, which largely restrain the flexibility, simplification, and miniaturization of the devices. Here, a battery‐free, wireless, and epidermal electrochemical system is presented for in situ biochemical sensing. The sensing component of the system is a stretchable electrode array all‐printed with soft polymer and conductive silver nanowires. The electrodes show stable electrical properties within strain range of 0–50%, without serpentine designs. The electronic component of the system is a fully integrated flexible circuit board with near field communication module, which enables wireless energy harvesting and data transmission with smartphones. The system demonstrates good performance in real‐time on‐body sweat analysis for simultaneous quantitative detections of glucose, hydrogen, sodium, and potassium. This battery‐free and wireless epidermal electrochemical system provides a simplified, miniaturized, and flexible solution for a wide range of biochemical platforms, including wearable and implanted bioelectronics.
In this work, we successfully prepared the musselinspired polydopamine microspheres (PDA-Ms) with controllable sizes, through a facile self-oxidative polymerization method. The prepared PDA-M biomaterial with environmentally benign properties exhibits efficient lead(II) sequestration against high salts of competitive Ca(II), Mg(II), or Na(I) ions. It reveals 30 times greater than the commercial ion-exchanger 001x7 by selectivity evaluation. Kinetic results show that an exceedingly rapid lead(II) uptake can be achieved below 1 min. More attractively, the prepared PDA-Ms further exhibit the distinguished application ability with superior treated capacity of ∼42000 kg contaminated water/kg sorbent, and the effluents can be reduced from 1000 μg/L to below 10 μg/L, reaching the drinking water standard (WHO), which is equal to 200 times greater than commercial ion exchanger resin (∼210 kg) and granular activated carbon (∼120 kg). In addition, the exhaust PDA-M material can be well regenerated and repeated use using binary 1% HCl + 5% Ca(NO 3 ) 2 solution. X-ray photoelectron spectroscopy (XPS), zeta potential, and FT-IR analysis prove that such satisfactory performances can be ascribed to the following aspects (1) the well-dispersed nanoscale morphology and highly charged property will achieve the rapid adsorption and sufficient sorbent utilization. That is, the negatively-charged PDA sphere can exert the famous Donnan membrane effects for target lead(II) enrichment and diffusion enhancement; (2) the strong amine and carbonyl/hydroxyl group within the matrix can offer sorption selectivity for powerful lead(II) capture. Effective performances as well as environmentally friendly features suggest PDA-M material is a promising lead(II)-removing candidate for water remediation.
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