Enzyme-based biocomputing systems were interfaced with signal-responsive membranes and electrodes resulting in bioelectronic devices switchable by logically processed biomolecular signals. "Smart" membranes, electrodes, biofuel cells, memristors and substance-releasing systems were activated by various combinations of biomolecular signals in the pre-programmed way implemented in biocatalytic cascades mimicking logic networks. Enzyme-based biocomputing systems were interfaced with signal-responsive membranes and electrodes resulting in bioelectronic devices switchable by logically processed biomolecular signals.
A sheet-type, stretchable biofuel cell was developed by laminating three components: a bioanode textile for fructose oxidation, a hydrogel sheet containing fructose as fuel, and a gas-diffusion biocathode textile for oxygen reduction. The anode and cathode textiles were prepared by modifying carbon nanotube (CNT)-decorated stretchable textiles with fructose dehydrogenase (FDH) and bilirubin oxidase (BOD), respectively. Enzymatic reaction currents of anode and cathode textiles were stable for 30 cycles of 50% stretching, with initial loss of 20–30% in the first few cycles due to the partial breaking of the CNT network at the junction of textile fibers. The assembled laminate biofuel cell showed power of ~0.2mW/cm2 with 1.2kΩ load, which was stable even at stretched, twisted, and wrapped forms. •A stretchable biofuel cell (BFC) with enzyme electrodes was constructed.•A nylon/polyurethane co-fiber textile was used as a stretchable underlying base material.•The two electrodes were stacked with a hydrogel sheet containing fuel.•The BFC showed power of ~0.2 mW/cm2 even at stretched, twisted, and wrapped forms.
Highlights • A novel, small wireless device for perspiration monitoring was developed. • The developed device consists of a stand-alone humidity sensor and desiccant. • Water vapor from the skin can be detected as perspiration by a humidity sensor. • The amount of perspiration can be calculated by the Fick's laws of diffusion. • Experiments involving human subject proved the validity of developed device.
A wearable electrochemical sensor for non-invasive monitoring of trace metals in human perspiration is described. The temporary tattoo-based printable stripping-voltammetric sensor has been applied for real-time monitoring of zinc in sweat using a bismuth/Nafion film electrode during physical activity. The Zn temporary tattoo sensor withstands repeated mechanical stress and displays a well-defined Zn response during on-body testing. Such a non-invasive stripping-voltammetric detection could be readily expanded to epidermal measurements of other relevant heavy metals. [Display omitted] •First example of a wearable trace metal electrochemical sensor is demonstrated.•Real-time monitoring of trace metal in human perspiration is described.•Flexible and robust printable tattoo sensors withstand mechanical stress.•Non-invasive epidermal stripping-voltammetric detection of trace metal is achieved.
Nowadays insight into human-machine interaction is a critical topic with the large-scale development of intelligent vehicles. Biosignal analysis can provide a deeper understanding of driver behaviors that may indicate rationally practical use of the automatic technology. Therefore, this study concentrates on biosignal analysis to quantitatively evaluate mental stress of drivers during automatic driving of trucks, with vehicles set at a closed gap distance apart to reduce air resistance to save energy consumption. By application of two wearable sensor systems, a continuous measurement was realized for palmar perspiration and masseter electromyography, and a biosignal processing method was proposed to assess mental stress levels. In a driving simulator experiment, ten participants completed automatic driving with 4, 8, and 12 m gap distances from the preceding vehicle, and manual driving with about 25 m gap distance as a reference. It was found that mental stress significantly increased when the gap distances decreased, and an abrupt increase in mental stress of drivers was also observed accompanying a sudden change of the gap distance during automatic driving, which corresponded to significantly higher ride discomfort according to subjective reports.
•Infrared thermography is suitable for measuring skin temperature in cycling tests.•Thermal contact sensors interfered in the heat exchange process of the cyclists.•Similar differences between methods were found in the instrumented and humans tests.•Large ROIs presented lower temperatures than small ROIs after cycling. The aim of the present study was to compare infrared thermography and thermal contact sensors for measuring skin temperature during cycling in a moderate environment. Fourteen cyclists performed a 45-min cycling test at 50% of peak power output. Skin temperatures were simultaneously recorded by infrared thermography and thermal contact sensors before and immediately after cycling activity as well as after 10min cooling-down, representing different skin wetness and blood perfusion states. Additionally, surface temperature during well controlled dry and wet heat exchange (avoiding thermoregulatory responses) using a hot plate system was assessed by infrared thermography and thermal contact sensors. In human trials, the inter-method correlation coefficient was high when measured before cycling (r=0.92) whereas it was reduced immediately after the cycling (r=0.82) and after the cooling-down phase (r=0.59). Immediately after cycling, infrared thermography provided lower temperature values than thermal contact sensors whereas it presented higher temperatures after the cooling-down phase. Comparable results as in human trials were observed for hot plate tests in dry and wet states. Results support the application of infrared thermography for measuring skin temperature in exercise scenarios where perspiration does not form a water film.
The influence of L-histidine on the light and perspiration stability of 4,4’-diamino-stilbene-2,2’-disulfonic acid-based fluorescent whiteness agents (DSD-based FWAs) for cotton fabrics was investigated in this paper. The results indicated that the single component L-histidine accelerated the photo-discoloration of DSD-based FWAs. In the absence of L-histidine, DSD-based FWAs tended to have poor light stability in the strongly acidic condition (pH 4). However, in the presence of L-histidine solution, the light stability of DSD-based FWAs was poorer than their counterparts without L-histidine, and was enhanced linearly with the growth of pH value. Therefore, absorption actions caused by L-histidine, oxidization-related promotion for FWAs and photo-decomposition of L-histidine in the acidic condition have been proposed to analyze the comprehensive effects of L-histidine in perspiration on the light stability of DSD-based FWAs on cotton fabrics.
Cu-5Zn-5Al-1Sn (89% Cu, 5% Zn, 5% Al, 1% Sn) and UNS C11000 copper (Cu) were compared with respect to corrosion rate, film formation, and Cu release in two surface conditions pertinent to the use of antimicrobial functional materials. Electrochemical, surface characterization, and solution analysis methods were utilized to track the fate of copper during corrosion in synthetic perspiration solution in a freshly ground condition and after 30-d lab air passivation. Corrosion behavior was a function of both alloy composition and surface condition with slightly lower corrosion rates on Cu-5Zn-5Al-1Sn compared to Cu. Throughout the corrosion process, the majority of Cu was observed to undergo dissolution into the synthetic perspiration solution as copper cations for both materials, at concentrations that would suggest favorable antimicrobial functionality for both Cu-5Zn-5Al-1Sn and Cu, regardless of surface condition. In contrast, oxide films were thinner on Cu-5Zn-5Al-1Sn under all conditions. Hence, the combination of a slightly lower corrosion rate and a thinner oxide resulted in a similar Cu release rate for the two materials in synthetic perspiration.