The present work describes the first example of real-time noninvasive lactate sensing in human perspiration during exercise events using a flexible printed temporary-transfer tattoo electrochemical biosensor that conforms to the wearer’s skin. The new skin-worn enzymatic biosensor exhibits chemical selectivity toward lactate with linearity up to 20 mM and demonstrates resiliency against continuous mechanical deformation expected from epidermal wear. The device was applied successfully to human subjects for real-time continuous monitoring of sweat lactate dynamics during prolonged cycling exercise. The resulting temporal lactate profiles reflect changes in the production of sweat lactate upon varying the exercise intensity. Such skin-worn metabolite biosensors could lead to useful insights into physical performance and overall physiological status, hence offering considerable promise for diverse sport, military, and biomedical applications.
Commercially pure Cu (Cu), Cu-4.5Sn-0.1Zn, and Cu-9.7Sn-0.1Zn (wt%) were evaluated for corrosion and cation release in modified artificial human perspiration solution. Open circuit corrosion exposures were conducted for up to 130hours to determine corrosion rate and the fate of Cu and Sn. Released aqueous ion concentrations were monitored via inductively-coupled plasma − optical emission spectroscopy (ICP-OES). Operando atomic emission spectroelectrochemistry (AESEC) analysis was utilized to elucidate the fate of Cu, whether in oxides or solution and deduce the dominant valence states, Cu(I)/Cu(II), of soluble Cu in artificial perspiration. Sn was not observed as a soluble ionic species within ICP-OES or AESEC limits of detection (LOD). Corrosion products were characterized using grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), and quantified with coulometric reduction (CR). Cu-4.5Sn-0.1Zn displayed the highest corrosion rates in artificial perspiration, followed by Cu-9.7Sn-0.1Zn, and then Cu. Primary corrosion products were Cu2O, with CuCl as an outer solid product, and an inner layer of SnO2 for Sn-containing alloys. Cu was dissolved as cuprous (Cu+) ions. Minor Sn alloying in solid solution catalyzed Cu dissolution which is counteracted at higher Sn contents by a passivating layer of SnO2, achieving complete passivity at 10.3wt% Sn according to graph theory. Cu-9.7Sn-0.1Zn indicated semi-passive behavior, speculated to be due a SnO2 layer and close proximity (9.7wt%) to this critical value for passivation (10.3wt%). The effect of alloyed Sn as a dissolution promoter for electrochemical Cu ion release, critical Sn contents for passivity, and subsequent implications of antimicrobial function are discussed. Oxidized Zn was not detected above LOD nor demonstrated any measurable effect on corrosion in artificial perspiration.
In this study, a bench-scale system was utilized to assess the disinfection byproduct (DBP) formation from human endogenous organic matter. Perspiration and urine, constituting the main organic substances in swimming pools, were selected to represent the major human endogenous organics. Results revealed that the continuous input of body fluids into the reactor led to rapid accumulation of endogenous organic matter, which contributed to high concentrations of DBPs in the swimming pool. The increase in nonpurgeable organic carbon (NPDOC) concentration from the perspiration precursor was lower than that from urine during the operation. Moreover, the accumulation of swimmers' body fluids leads to increased DBP precursors, as well as increased chlorine demand and DBP formation in swimming pool water. The concentration of the trihalomethanes (THMs) and haloacetic acids (HAAs) consistently increased during the reaction. More THMs were generated in urine solution, whereas more HAAs were found in perspiration solution. To improve the water quality in swimming pools, ozonation, UV/Chlorine, and UV/H2O2 treatments were evaluated for their efficacy in reducing the DBP precursors. Results revealed that all of the three treatment processes can degrade the DBP precursors in perspiration and urine, eventually decreasing the DBP concentrations. However, only the UV/H2O2 treatment can decrease the formation of DBPs in perspiration and urine. In addition, the results revealed that UV/Chlorine and UV/H2O2 treatments should be operated for a sufficient contact time to prevent the increased production of DBP precursors in water at the early stage of the treatment. [Display omitted] •DBP formation from endogenous organic matter in swimming pool was assessed.•Continuous input of perspiration and urine led to accumulation of organic matter.•Ozonation, UV/Chlorine, and UV/H2O2 can degrade the DBP precursors in water.•UV/H2O2 can decrease the DBP formation from perspiration and urine.•A longer contact time is needed for UV/Chlorine and UV/H2O2 to reduce DBP precursors.
Functional laser scribing carbon paper (LSCP) decorated with highly uniform Ni nanoparticles were constructed through a facile electroless plating. The nanocomposites were characterized by high resolution scanning electron microscope, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, cyclic voltammetry and chronoamperometry. The results showed high electron transferring kinetics of this sensor, which can be ascribed to their excellent properties such as rich pore channels, excellent structural durability, and large surface area. These properties facilitated mass transfer and electron conductions. Notably, a systematical response surface methodology simulating-modeling-predicting-optimizing design was employed to simulate, model and optimize processing parameters to gain the optimal conductivity of 8.52 × 106 S m−1. The obtained sensor owned high electrochemical activity and wide linear responses (0.80 μM–2.50 mM and 4.50 mM–15.20 mM), low detection limit of 20 nM (S/N = 3) to the glucose detection. The glucose determination in human serum and perspiration samples are also successful. Therefore, LSCP/NN provides an excellent sensing platform towards flexible biosensors in monitoring physical conditions. Disposable, Non-enzymatic and Ultrasensitive Carbon Fiber Paper-based Glucose Sensor has been Constructed by A Theoretical Box-Behnken Modeling-Predicting-Optimizing Design. [Display omitted] •A disposable, ultrasensitive and highly flexible LSCP/NN glucose biosensor is firstly constructed.•Novel nanoporous Ni networks are integrated with pulsed laser-scribed carbon paper via a rational Box-Behnken modeling-predicting-optimizing design.•The enzyme-free and binder-free LSCP/NN biosensor exhibits a wide linear glucose determination range (0.80 μM–2.50 mM; 4.5 mM–15.2 mM).•Excellent sensitivity (3415 μA mM−1 cm−2), a fast response (<1 s) and ultra-low limit of detection (20 nM).•Favorable flexibility, good accuracy and satisfactory specificity for glucose quantification in human serum and perspiration are indicated by the LSCP/NN biosensor.
Infrared camouflage without resorting to existing and often burdensome technologies is clearly attractive. In this paper, we explored a new approach to potentially achieve the infrared camouflage by facilitating the latent heat transfer while controlling the sensible heat transfer of the human body. A multilayer structure of the corresponding camouflage cloth prototype with specific functions for each layer is proposed here (layer I to layer IV, from the body skin to the outside, respectively). Since the requirements for cloth infrared camouflage at steady state are much stricter than at transient period, a steady state model for this prototype is developed to test its feasibility. The influences of related key parameters, including the porosity and the thickness for each layer are discussed using the model. The results show that a satisfactory infrared camouflage may be accomplished using all the layers proposed under specified structural conditions. In order to achieve the best effect of camouflage, for example, when the environment temperature is 296.15 K with 30% relative humidity, we further discovered that (1) the porosities of layer I and layer II should be lower as 5%, but those of layer III and layer IV should be relatively higher (85% and 90%, respectively); and (2) the thickness of the second layer should be greater enough to 1.5 cm, but the thickness of layer IV must be sufficiently thin at 0.1 cm. In summary, our proposed prototype provides a promising design for the uniform that can be used to suppress the probability of infrared detection. ► A new approach to potentially achieve infrared camouflage of human body is explored. ► This camouflage achievement is based solely on human perspiration. ► A multilayer structure of the corresponding cloth prototype is proposed. ► A steady state model is set up to demonstrate the feasibility. ► The influences of related important parameters are discussed.
Display omitted] •An ultrasensitive and highly flexible glucose biosensor is constructed.•Porous copper networks are integrated with a laser-scribed carbon paper substrate.•A wide linear glucose determination range from 1.0 μM to 7.96 mM.•An ultrahigh sensitivity, a fast response and ultra-low limit of detection.•Excellent flexibility, good accuracy and satisfactory specificity. Owing to the high specific surface area and easy accessability to targeting biomolecules, emerging non-noble-metal networks are developed as an ultra-active catalyst for molecular detection. In this work, a facile flexible enzyme-free glucose sensor with superior sensing performance has been successfully constructed by integrating laser-scribed carbon paper (LSCP) with copper network (CN). Remarkably, operation parameters are modeled and optimized by Central Composite Design (CCD) to obtain an optimal conductivity of 4.783 × 107 S·m−1 for CN. Due to the great electronic/ionic pathway between LSCP of ample active sites and CN of excellent conductivity, the disposable biosensor exhibits fast electron transfer kinetics. For glucose detection, LSCP/CN exhibits an excellent sensitivity of 3626.6 μA mM−1 cm−2, a wide linear range from 1 μM to 7.96 mM, an ultra-low detection limit of 30 nM (S/N = 3) as well as favorable reusability. Satisfactory anti-interference capacity to electro-active oxides and selectivity against carbohydrates studied for concentrations up to normal physiologic levels and higher concentrations are systematically investigated. The applications of glucose determination in human serum and perspiration samples are also successful, with recoveries of 100.8% (± 2.28%) and 92.1% (±3.61%), respectively. Experimentally, the current response of the LSCP/CN biosensor is resilient to mechanical deformation with less than 8% decay even after 1000 cycles of 1 mm repeated bending and 180° cyclical folding tests. As such, LSCP/CN can be applicable for flexible, attachable and potentially wearable biosensors to attain real-time physiological monitoring.
A new portable electrochemical sensor based on 4-aminobenzoic acid-modified herringbone carbon nanotubes (hCNTs-4ABA/Au-IDA) has been developed for the simultaneous determination of ascorbic acid (AA) and uric acid (UA) in physiological fluids. AA and UA were quantified by chronoamperometry at 0.1 and 0.32 V, respectively, in phosphate buffer solution (PBS 0.25 M, pH 7.0). Significant results were obtained for the separate quantification of AA and UA, with a limit of detection (LOD) of 0.65 μM for both analytes, and sensitivities of (9.0 ± 0.4) A g−1 mM−1 and (8.8 ± 0.3) A g−1 mM−1 for AA and UA, respectively. Repeatability was studied at 50 μM for AA and UA, providing relative standard deviations (RSD) lower than 9%. Additions of glucose, dopamine and epinephrine did not interfere with the AA and UA determination. Furthermore, UA did not interfere with AA determination at 0.1 V, although AA additions increased the current recorded at 0.32 V. The method has been successfully applied to human urine, perspiration and serum samples, without significant matrix effects, which allows for the use of an external calibration and the analysis of all the matrices investigated. •Electrochemical and portable sensor based on 4-aminobenzoic acid-herringbone carbon nanotubes.•Simultaneous quantification of ascorbic acid and uric acid in physiological fluids has been done.•The sensor has been successfully used on human urine, perspiration and serum, without matrix effects.
► A multilayer cloth structure was proposed and examined for perspiration based infrared camouflage of human body. ► Several experiments were conducted to demonstrate and validate the feasibility. ► The influences of related important parameters were discussed. ► General criterion in designing comfort performance of a cloth system was established. Rather than resorting to extrinsic aids, like using additional heat insulation/storage or phase change materials or surface coatings as in other current infrared camouflage technologies, a new scheme of perspiration based infrared camouflage and a corresponding multi-layer cloth prototype were proposed recently by the present authors. In this paper, several experiments were conducted on a three-layer system based on the proposed prototype, and the original theories were modified to suit the experimental system. The experimental results compared well with the theoretical predictions in verifying the principle of proposed perspiration based infrared camouflage, and in examining the effects of such factors as layer thickness and layer sequence. More importantly, through a heat flux analysis, we found that the ratio of the latent heat flux to the sensible heat flux (ql/qs) can be used as a general criterion in designing the comfort performance of a cloth system. For the perspiration based infrared camouflage: the higher the ratio, the better the infrared camouflage effect.
Commonly used as flame retardants, polybrominated diphenyl ethers (PBDEs) are routinely detected in the environment, animals, and humans. Although these persistent organic pollutants are increasingly recognized as having serious health implications, particularly for children, this is the first study, to our knowledge, to investigate an intervention for human elimination of bioaccumulated PBDEs. Objectives. To determine the efficacy of blood, urine, and perspiration as PBDE biomonitoring mediums; assess excretion of five common PBDE congeners (28, 47, 99, 100, and 153) in urine and perspiration; and explore the potential of induced sweating for decreasing bioaccumulated PBDEs. Results. PBDE congeners were not found in urine samples; findings focus on blood and perspiration. 80% of participants tested positive in one or more body fluids for PBDE 28, 100% for PBDE 47, 95% for PBDE 99, and 90% for PBDE 100 and PBDE 153. Induced perspiration facilitated excretion of the five congeners, with different rates of excretion for different congeners. Conclusion. Blood testing provides only a partial understanding of human PBDE bioaccumulation; testing of both blood and perspiration provides a better understanding. This study provides important baseline evidence for regular induced perspiration as a potential means for therapeutic PBDE elimination. Fetotoxic and reproductive effects of PBDE exposure highlight the importance of further detoxification research.
People with limb amputation deal with thermal stresses in their daily activities. Unfortunately, in the majority of this population, all thermal transfer mechanisms, including convection, radiation, evaporation, and conduction, can be disturbed due to the prosthetic socket barrier, decreased body surface area, and/or vascular disease. The thermal environment inside prosthetic sockets, in addition to decreased quality of life and prosthesis use, comfort, and satisfaction, could put people with amputation at high risk for skin irritations. The current review explores the importance of thermal and perspiration discomfort inside prosthetic sockets by providing an insight into the prevalence of the problem. The literature search was performed in two databases, PubMed and Web of Knowledge, to find relevant articles. After considering the review criteria and hand-searching the reference sections of the selected studies, 38 studies were listed for review and data extraction. This review revealed that more than 53% of people with amputation in the selected studies experienced heat and/or perspiration discomfort inside their prostheses. In spite of great technological advances, current prostheses are unable to resolve this problem. Therefore, more attention must be paid by researchers, clinicians, and manufacturers of prosthetic components to thermal-related biomechanics of soft tissues, proper fabrication technique, material selection, and introduction of efficient thermoregulatory systems.