Electronic skin (e‐skin), an important part toward the realization of artificial intelligence, has been developing through comprehending, mimicking, and eventually outperforming skin in some aspects. Most of the e‐skin substrates are flexible polymers, such as polydimethylsiloxane (PDMS). Although PDMS was found to be biocompatible, it is not suitable for long‐time wearing due to its air impermeability. This study reports a simple and designable leather based e‐skin by merging the natural sophisticated structure and wearing comfort of leather with the multifunctional properties of nanomaterials. The leather based e‐skin could make leather, “the dead skin,” repurposed for its sensing capabilities. This e‐skin can be applied in flexible pressure sensors, displays, user‐interactive devices, etc. It provides a new class of materials for the development of multifunctional e‐skin to mimic or even outshine the functions of real skin.
Permanganate was activated by ultraviolet (UV) photolysis at 254 nm, resulting in the efficient degradation of micropollutants. The degradation of four probe molecules (i.e., nitrobenzene, benzoic acid, terephthalic acid, and p-chlorobenzoic acid) and two micropollutants (i.e., gemfibrozil and nalidixic acid) resistant to permanganate oxidation was enhanced by the UV/ permanganate system, with pseudo-first-order rate constants (k′) of 0.065−0.678 min −1 under the experimental conditions. Hydroxyl radicals (HO • ) and Mn(V) peroxide, which were produced during the activation of permanganate by UV irradiation, were responsible for the enhancement. The quantum yield of HO • was 0.025 ± 0.001 mol Einstein −1 (mol Es −1 ) in the system. HO • oxidation primarily accounted for the degradation of nitrobenzene and gemfibrozil, while both HO • and Mn(V) were responsible for the degradation of benzoic acid, terephthalic acid, p-chlorobenzoic acid, and nalidixic acid. This study is the first report on the activation of permanganate by UV irradiation for the abatement of micropollutants in water treatment, which may lead to a new advanced oxidation process relying on both HO • and reactive manganese species.
Flexible transparent conductive electrodes (FTCEs) are essential components for numerous optoelectronic devices. In this work, we have fabricated the hierarchical metal grids (HMG) FTCEs by a facile and low-cost, near-field photolithography strategy. Compared to normal metal grids (MG), the HMG structure can provide distinctly increased conductivity of the electrode yet without obvious reduction of the optical transmittance. This HMG sample possesses excellent optoelectronic performance and high mechanical flexibility, making it a promising component for practical applications.
This paper presents a study of the effect of a combined biostimulation-bioaugmentation treatment applied to a clay-loam soil contaminated with 16,300 mg/kg of total petroleum hydrocarbons (TPH), which comprised 51% saturated hydrocarbons and 31% aromatic hydrocarbons. The bioaugmentation was performed with yeast Candida tropicalis SK21 isolated from petroleum-contaminated soil. The strain was able to grow in a pH range of 3-9 in liquid culture, and the optimum pH was found to be 6 for both growth and biosurfactant production. At pH 6, 96% and 42% of TPH were degraded by the strain at the initial diesel oil concentrations of 0.5% and 5% (v/v), respectively. The remediation via inoculating the yeast removed 83% of TPH in 180 days while the experiment with the indigenous microorganisms alone removed 61%. Microbial enumeration showed that the yeast SK21 could grow good in the soil. It was also found that dehydrogenase and polyphenoloxidase activities in soil were remarkably enhanced by the inoculation of the yeast.
Flexible electronics are playing an increasingly important role in human health monitoring and healthcare diagnosis. Strong adhesion on human tissue would be ideal for reducing interface resistance and motion artifacts, but arising problems such as skin irritation, rubefaction, and pain upon device removal have hampered their utility. Here, inspired by the temperature reversibility of hydrogen bonding, a skin-friendly conductive hydrogel with multiple-hydrogen bonds was designed by using biocompatible poly(vinyl alcohol) (PVA), phytic acid (PA), and gelatin (Gel). The obtained PVA/PA/Gel (PPG) hydrogel with temperature-triggered tunable mechanic could reliably adhere to skin and detect electrophysiological signals under a hot compress while be readily removed under a cool compress. Furthermore, the additional advantages of transparency, breathability, and antimicrobial activity of the PPG hydrogel ensure its long-time wearable value on the skin. It is both environmentally friendly and cost saving for the waste PPG hydrogel during production can be recycled based on their reversible physical bonding. The PPG hydrogel sensor is expected to have good application prospects to record electrophysiological signals in human health monitoring.
This
article presents a leather-based respiration sensor based
on the ionic conductivity change of leather, caused by humidity variation
during breathing. Leather was applied as a flexible substrate due
to its biocompatibility, hydroscopicity, porosity, and ionic conductivity.
Printing method was employed to fabricate the sensor, which could
convert human respiration to electrical signals. By combining the
leather with silver nanowires (AgNWs), data about human respiration
rate, respiration depth, and respiration pattern can be acquired easily
through a noninvasive way. Such sensor could work tens of hours consecutively
due to the unique properties of leather.
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