Presence Of Sweat Research Articles

Design and Testing of Autonomous Chargeable and Wearable Sweat/Ionic Liquid-Based Supercapacitors.

This work demonstrates ionic liquid electrolyte‐inscribed sweat‐based dual electrolyte functioning supercapacitors capable of self‐charging through sweat electrolyte function under a non‐enzymatic route. The supercapacitor electrodes are fabricated from TREN (tris(2‐aminoethyl)amine), poly‐3,4‐ethylenedioxythiophene, and a graphene oxide mixture with copper‐mediated chelate, and this polymer‐GO‐metal chelate film can produce excellent energy harvest/storage performance from a sweat and ionic liquid integrated electrolyte system. The fabricated device is specifically designed to reduce deterioration using a typical planar structure. In the presence of sweat with ionic liquid, the dual electrolyte mode supercapacitor exhibits a maximum areal capacitance of 3600 mF cm−2, and the energy density is 450 mWhcm−2, which is more than 100 times greater than that from previously reported supercapacitors. The supercapacitors were fabricated/attached directly to textile fabrics as well as ITO‐PET (Indium tin oxide (ITO)‐polyethylene terephthalate (PET) film to study their performance on the human body during exercise. The self‐charging performance with respect to sweat wetting time for the sweat@ionic liquid dual electrolyte showed that the supercapacitor performed well on both fabric and film. These devices exhibited good response for pH effect and biocompatibility, and as such present a promising multi‐functional energy system as a stable power source for next‐generation wearable smart electronics.

(Invited) Transdermal Alcohol Monitoring with a Printed Amperometric Sensor

(Invited) Transdermal Alcohol Monitoring with a Printed Amperometric Sensor

Electron transfer studies of a conventional redox probe in human sweat and saliva bio-mimicking conditions

Modern day hospital treatments aim at developing electrochemical biosensors for early diagnosis of diseases using unconventional human bio-fluids like sweat and saliva by monitoring the electron transfer reactions of target analytes. Such kinds of health care diagnostics primarily avoid the usage of human blood and urine samples. In this context, here we have investigated the electron transfer reaction of a well-known and commonly used redox probe namely, potassium ferro/ferri cyanide by employing artificially simulated bio-mimics of human sweat and saliva as unconventional electrolytes. Typically, electron transfer characteristics of the redox couple, [Fe(CN)6]3−/4− are investigated using electrochemical techniques like cyclic voltammetry and electrochemical impedance spectroscopy. Many different kinetic parameters are determined and compared with the conventional system. In addition, such electron transfer reactions have also been studied using a lyotropic liquid crystalline phase comprising of Triton X-100 and water in which the aqueous phase is replaced with either human sweat or saliva bio-mimics. From these studies, we find out the electron transfer reaction of [Fe(CN)6]3−/4− redox couple is completely diffusion controlled on both Au and Pt disc shaped electrodes in presence of sweat and saliva bio-mimic solutions. Moreover, the reaction is partially blocked by the presence of lyotropic liquid crystalline phase consisting of sweat and saliva bio-mimics indicating the predominant charge transfer controlled process for the redox probe. However, the rate constant values associated with the electron transfer reaction are drastically reduced in presence of liquid crystalline phase. These studies are essentially carried out to assess the effect of sweat and saliva on the electrochemistry of Fe2+/3+ redox couple.

Transdermal Alcohol Monitoring with a Printed Amperometric Gas Sensor

Introduction We report development of a prototype transdermal ethanol (EtOH) monitor, in wristwatch format, to provide a modern device for consumer, clinical and law enforcement applications. Our vision is an attractive, comfortable smart watch, which will measure transdermal alcohol concentration (TAC) and predict blood alcohol concentration (BAC) during drinking. Current commercially available alcohol monitors are bulky, ankle-fixed devices, predominantly used in court-ordered monitoring and some research studies [1]. There has been little advancement in wearability, comfort and analytical performance of these devices. Our long-term goal is to realize a new generation of wearable monitor that combines a sensitive ethanol measurement and smartwatch capabilities in a comfortable and attractive package. This device could greatly expand the possible applications employing this technology. Experimental Watch Fabrication. The sensor platform was fabricated based on a scaled down version of our dual gas sensor platform and printed amperometric gas sensor [2, 3]. The simple prototype device contains a single EtOH sensor, analog front end, 24 bit ADC, Bluetooth LE chip and T/P/RH sensor. The board is contained in a commercially available wristwatch enclosure (BodyCase B1606117) as in Fig. 1. Initial tests of linearity and S/N showed that the circuit was linear over at least 0-300 ppm EtOH at 25 C (R2 = 0.9996 – 0.9998 for 4 boards) with sensitivity 23 ± 2 nA/ppm (for 4 boards) and limit of detection (LOD) 0.26 ± 0.06 ppm.Laboratory Testing. A flow cell was designed to deliver 0 – 0.4 w/o EtOH (simulated BAC) through a Strat-M membrane, which served as a skin surrogate [4]. EtOH solutions in phosphate buffered saline pH 7.1 were used. The cell was configured such that EtOH permeated the Strat-M, with vapor entering the headspace above to which the watch was interfaced. Results and Conclusions Flow Cell Tests. EtOH steps between 0 and 0.4 %EtOH (simulated BAC) were applied with 30 min exposure at each step. A 6 hr stability test was included. High stability and S/N were demonstrated. The EtOH concentrations in simulated BAC solutions were standardized and calibrated to headspace vapor phase concentrations, giving a calibration curve for %EtOH in the PBS buffer (simulated %BAC) as a function of measured EtOH (ppm EtOH) in headspace above the membrane. For two devices, we obtained highly linear calibrations (R2 = 0.9983, 0.9992, respectively) with slope of 0.0013% and 0.0011% BAC/ppm EtOH, with near zero intercepts (-0.009 and -0.006 %BAC, respectively). From these two tests and the baseline noise we determined a limit of detection (LOD) of ±0.005% BAC. In later tests (e.g., Fig. 2) the LOD was considerably improved. The 6 hr stability test at 0.12% EtOH showed very stable output of 0.116 ±0.003 % EtOH.Human Tests. An example of real transdermal alcohol measurement using the watch prototype on a human subject is shown in Fig. 2. A male volunteer ingested six 6 oz. aliquots of 5 v/o alcoholic beverage over ca. 1 hr. Two different watches were used, one fixed to each wrist. The measured temperature at the devices was typically in the range 28 – 34 C during tests. The data in Fig. 2 are not temperature compensated. A commercial BACtrack Trace breathalyzer was used to collect contemporaneous breath alcohol data (BrAC).The TAC measurements taken on two wrists correlated quite well with each other. The TAC values tracked BrAC trend qualitatively, but with a shift to longer times, with the peak BrAC occurring ca. 1.5 hours before the peak TAC value. In other tests we have also observed lags on the order 30 min to 2 hr for TAC vs. BrAC measures. This lag is well-known for transdermal ethanol measurements [5] and presents a challenge for reliable instantaneous BAC prediction from TAC data. We note that the lag can depend on many factors including person-to-person variability of skin permeability, presence of sweat (humidity), food consumption and variable rates of alcohol consumption and metabolism, to name a few examples. Mechanical effects such as sudden movements and impacts can also affect the measurement.We demonstrated use of a printed amperometric sensor for TAC measurement. Controlled clinical trials are currently being performed in collaboration with Boston Medical Center. The ultimate goal is to reliably predict BAC from TAC data across a broad range of individuals and use cases.

Gas-Permeable, Ultrathin, Stretchable Epidermal Electronics with Porous Electrodes.

We present gas-permeable, ultrathin, and stretchable electrodes enabled by self-assembled porous substrates and conductive nanostructures. An efficient and scalable breath figure method is employed to introduce the porous skeleton, and then silver nanowires (AgNWs) are dip-coated and heat-pressed to offer electric conductivity. The resulting film has a transmittance of 61%, sheet resistance of 7.3 Ω/sq, and water vapor permeability of 23 mg cm-2 h-1. With AgNWs embedded below the surface of the polymer, the electrode exhibits excellent stability in the presence of sweat and after long-term wear. We demonstrate the promising potential of the electrode for wearable electronics in two representative applications: skin-mountable biopotential sensing for healthcare and textile-integrated touch sensing for human-machine interfaces. The electrode can form conformal contact with human skin, leading to low skin-electrode impedance and high-quality biopotential signals. In addition, the textile electrode can be used in a self-capacitance wireless touch sensing system.

Coefficient of Friction Measurements on Transfemoral Amputees

Friction at the residual-limb socket interface affects amputees' comfort since it has a direct impact on the pain and functionality of the prosthesis. In this research, the coefficient of friction was measured at the volar forearm and three regions of the transfemoral residual limb (i.e., pressure tolerant, pressure sensitive, and scar region). The socket internal texture was replicated on a probe made of polypropylene to resemble the interface conditions. Besides the anatomical location, the presence and absence of sweat at the interface were evaluated. The statistical analysis included an ANOVA for two-factor experiment with repeated measures on one factor (sweat), where only sweat was found to be statistically significant (p − value = 0.001). Furthermore, regression analysis for the presence and absence of sweat condition was developed since its presence seems to homogenize the interaction conditions by surpassing the effect of other factors on skin friction. The presence of stick-slip phenomenon at the interface, the skin deformation during measurements, and the use of a portable tribometer led to the large variability in results, with larger variability in the presence of sweat. Hence, the relationship between the sweat layer thickness and the coefficient of friction should be explored.

Instrumentation for Measuring the Wet Frictional Property of Sanitary Pads

Women wear sanitary pad for whole day during their menstruation period. They have direct skin contact with it even for sleeping and exercising. The presence of sweat and menstrual blood increases the moisture level and the adhesion of liquid to textile causing sensorial discomfort. This study describes the design and uses of modified Textile Stickiness Measurement System (TSMS) which can characterize the frictional properties of sanitary pads under both dry and wet conditions. The uniqueness of this measurement system is that the wetness level of the pad is adjustable and the surface profile of the contacting object (i.e. Lorica®Soft) does simulate the condition of human skin. Also, it does not have restriction on the type of sanitary pad that can be tested. Among the 12 sanitary pads tested (disposable and reusable types), the frictional force for the disposable sanitary pads is lower than the reusable pads whilst the performance of disposable sanitary pads with nonwoven surface is lower than the one with perforated surface. These can attribute to their liquid transport property and surface feature. For those with better liquid transport property, less water will stay on skin surface and so the adhesion between skin and textiles is lower. For those with protruding fibers on its surface, it reduced the contact area and so the frictional force is lower.

Survival of Microorganisms on Filtering Respiratory Protective Devices Used at Agricultural Facilities.

Bioaerosol is a threat at workplaces, therefore the selection and safe use of filtering facepiece respirators (FFRs) is important in preventive activities. The aim of the study was to assess the survival of microorganisms on materials used for FFRs construction. The parameters for microorganism growth under model conditions were described using the Gompertz equation, model verification was also carried out using FFRs at the farmers’ workplaces. We found that the factors determining a high survival of microorganisms were as follows: moisture corresponding to the conditions of use and storage of FFRs at workplaces, the presence of sweat and organic dust; inorganic dust and addition of biocide in nonwovens limited the growth of microorganisms, resulting in a shortening of the stationary growth phase and decreased cell numbers (5–6 log). Dust concentration at workplaces was higher than EU occupational exposure limit values and WHO recommendations for airborne particulate matter. Microbial contaminations of the air (103–104 CFU/m3), settled dust (104–106 CFU/g) and FFRs (105 CFU/4cm2) during the grain harvest were high, the main contamination being bacteria (actinomycetes, Pseudomonas fluorescens) and xerophilic fungi. A high correlation was found between the number of microorganisms and the weight of dust on FFRs (R2 = 0.93–0.96).

Sweat as energy source using an enzymatic microfluidic fuel cell

An enzymatic microfluidic fuel cell was constructed to produce energy from lactate and oxygen preset in the sweat. In this case, laccase (Lc) connected to anthracene modified carbon nanotubes (An-MWCNT) to facilitate the direct electron transfer (DET) as the biocathode and lactate oxidase (LOx) as the bioanode, both enzymes were immobilized on Toray Carbon Paper (TCP). The oxygen reduction reaction (ORR) showed better results in a pH acid, which agrees with the slightly acid pH of sweat. On the other hand, the Lc showed to have good catalytic activity towards ORR in the presence of sweat, since only about 10% was inhibited after having added 660 µl of sweat. Finally, the enzymatic microfluidic fuel cell was capable to generate 64 µW cm-2 when sweat was fed into both electrodes, this confirms the high selectivity of the LOx and Lc towards lactate oxidation and oxygen reduction, respectively. These results are the first step to design an stamped device to produce energy in real time taking advantage of the sweat produced during workouts.

Antioxidant cosmetotextiles: Cotton coating with nanoparticles containing vitamin E

Abstract In the present study, we coated cotton fabrics with protein-based nanoparticles containing vitamin E (α-tocopherol) by the pad-cure method. Scanning electron microscopy, Fourier transform infra-red spectroscopy, and air permeability analysis of coated samples confirmed the fixation of the nanoparticles onto the fabric’s surface. The antioxidant activity of the coated fabrics was evaluated by 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radicals reduction. Samples coated with nanoparticles containing the highest amount of encapsulated vitamin E (20% of the oil phase) showed the highest antioxidant activity. The protein-based coating was maintained for at least 10 washing cycles, demonstrating the reliability of the pad-cure method for the fixation of nanoparticles onto cotton surfaces. A methodology for nanoparticles release from the coated surfaces and their transfer to other substrates was demonstrated by the simple crock meter rubbing in the presence of sweat and protease. A high amount of material can be transferred and released to other substrates, such as textiles and skin, through the synergistic effect of sweat/protease and abrasion. An array of cosmetic and medical applications are possible with the developed coating and release methodology in which vitamin E would impart vital benefits as skin protection, anti-ageing product, or skin moisturizer.

Evaluation of water absorption and transport property of fabrics

The liquid absorption and transport properties of fabrics are critical not only to the success of wet processes such as dyeing, printing and finishing, but also to the performance of products such as sports clothes, performance clothing, disposable hygiene materials and medical products. During wear, moisture in clothing has been found to be the most significant factor contributing to discomfort. The presence of sweat will increase friction between fabric and skin, trigger a clingy sensation and eventually increase the level of fatigue felt by the wearer. This problem will be even more severe for clothing worn under extreme environmental conditions or at high activity levels. Fabrics with excellent water absorption and transport properties have the potential to minimise the wetness sensation on skin, facilitate the evaporation of sweat and aid comfort. Hence, as a product developer or clothing manufacturer, it is essential to choose the appropriate measurement method to characterise the water absorption and transport properties of fabric.This paper reviews different subjective (by people–subjects) and objective (by instruments–objects) evaluation methods for assessing wetness comfort, and determining water absorption and transport properties of fabrics. Since perception of wetness is a complex process with a number of stimuli from clothing and external environments communicated by human sensory receptors, subjective assessment with its better representation of the real wear situation is preferred. The review starts by introducing human physiology, describing hepatic perception of wetness, followed by methods for use in experiments on assessor control, setting of environmental conditions, types of touch, the usual body sites for testing, and a summary of methods for measuring physiological and perception changes using psychological or psychophysical scaling procedures. Despite its advantage of more closely simulating the real wear condition, performing a subjective test is time-consuming and expensive. Its accuracy depends on the reliability of the assessors and the result may vary between assessors. Objective measurement might therefore provide an attractive alternative. In this study, details of objective instrumental measurements are summarised according to the technology applied, and include gravimetric, observation-based, optical, spectroscopic, electrical, pressure-based, magnetic resonance and temperature detection methods. The principles, advantages and limitations of each method are systematically compared and discussed. Practical recommendations are proposed, particularly for enhancing the accuracy, reproducibility and/or simplicity of the methods.The objective of this review is to present an overview of various measurement methods, both subjective and objective. It is intended to form a basis for enabling fabric engineers to choose the most suitable analytical test method(s) when developing new fabric products with respect to performance, the availability of resources, time for testing, the type of fabrics to be tested and the accuracy and precision required. Additionally, the review points to the need for researchers to develop more advanced and accurate measurement methods to characterise the absorption and transport properties of fabrics.

Understanding the Friction Mechanisms Between the Human Finger and Flat Contacting Surfaces in Moist Conditions

Human hands sweat in different circumstances and the presence of sweat can alter the friction between the hand and contacting surface. It is, therefore, important to understand how hand moisture varies between people, during different activities and the effect of this on friction. In this study, a survey of fingertip moisture was done. Friction tests were then carried out to investigate the effect of moisture. Moisture was added to the surface of the finger, the finger was soaked in water, and water was added to the counter-surface; the friction of the contact was then measured. It was found that the friction increased, up until a certain level of moisture and then decreased. The increase in friction has previously been explained by viscous shearing, water absorption and capillary adhesion. The results from the experiments enabled the mechanisms to be investigated analytically. This study found that water absorption is the principle mechanism responsible for the increase in friction, followed by capillary adhesion, although it was not conclusively proved that this contributes significantly. Both these mechanisms increase friction by increasing the area of contact and therefore adhesion. Viscous shearing in the liquid bridges has negligible effect. There are, however, many limitations in the modelling that need further exploration.

Relationship between skin resistance level and static balance in type II diabetic subjects

Diabetes mellitus is major cause leading to pathological changes in skin foot plantar area (SFPA) and affected the static standing balance duration (SSBD). Skin resistance level (SRL) is related to skin conductance which changes in the presence of sweat. This study aims to find out the relationship between the SRL and SSBD in type II diabetic patients. Sixty-eight voluntary students, 30 type II diabetic patients and 30 healthy non-diabetic subjects, were participated to the study. The SSBD was measured on dominant and non-dominant legs. SRLs were recorded with two surface electrodes over the metatarsus heads and heel. The SSBD of the healthy young group was found to be higher than the other groups ( P < 0.001). The SRL values of the non-dominant leg in the diabetic group was found to be lower than the others ( P = 0.014). For dominant and non-dominant legs within each group, only the healthy young group has statistically difference ( P = 0.012). A significant correlation was seen to be between the SRL and SSBD for only healthy non-diabetic group for the non-dominant leg. The relation between the SRL and SSBD is poor but very promising. Measurement of the SRL can be used in evaluating the inflammation of the diabetic foot.

Electrochemical impedance spectroscopy as an objective method for characterization of textile electrodes

Textile electrodes are being developed for monitoring, eg, heart and respiration rate. Textile materials are comfortable and thus enable long-term monitoring. This flexibility, however, leads to many artefacts in the signals. One of the main problems in testing such sensors on a human body is the huge variability of the latter. This paper describes and objective method that enables accurate and reproducible characterization of textile electrodes using electrochemical impedance spectroscopy. The effect of textile structure, presence of sweat, sensor size and long-term stability are being studied.

Latexhandschuhe im Hautkontakt – gibt es Risiken?

Allergies to rubber parts, especially to natural rubber latex gloves, are a widespread phenomenon and are frequently described in the literature. The presented investigation is based on 6 NR latex gloves and reveals a whole string of extractable rubber chemicals which can irritate the human skin when these gloves are used. On the one hand conventional qualitative and quantitative methods for the analysis ofrubber chemicals present in the gloves via methanol extraction followed by HPLC were applied. On the other hand special emphasis was layed on the question, how much of these chemicals can be absorbed by human skin in ordinary use of gloves. This includes also possible chemical reactions in the presence of sweat and the influence of a hand disinfectant which is commonly used e.g. in hospitals. Various approaches were investigated for the laboratory simulation of a hand wearing a glove. As a result, it could be shown that the desinfectant increases the concentration of irritating chemicals and components were able to permeate through the elastomer. The extraction of zincdimethyldithio-carbamate (ZDMC) and mercaptobenzothiazole (MBT) was monitored as a function of time, temperature and pH value similar to a BGA method. In addition, a rough estimation of the quantities of these chemicals, which can permeate to the skin while wearing the gloves, was done. For ZDMC an exposition of 0,7 mg, for MBT of 2 mg per hand and day was found. The combination of sweat and extractable chemicals can obviously produce chemicals as for example tetramethylthiuramedisulfide (TMTD). This hazardous substance could be detected in small amounts although the methanol extract was apparently free of TMTD. A profound toxicological evaluation of the indicated compounds is not part of this paper. The investigation also shows that it is possible to produce rubber gloves which are approximately free of polar and thus water soluble pollutants.

LIGHTNING STRIKE TO THE HEAD

A case is presented of a teen-aged athlete who sustained a direct lightning strike to the head while wearing a football helmet. The helmet, the presence of sweat, and aggressive resuscitation were instrumental in his survival and complete recovery. This appears to be the first documentation of a lightning strike to an individual wearing protective headgear.

Permethrin transfer from treated cloth to the skin surface: potential for exposure in humans.

Permethrin is an agricultural insecticide of great interest to the military because of its repellency toward disease-bearing insects when impregnated into uniforms. However, migration of the substance from clothing to the skin surface is of toxicological importance. To quantitate leaching from treated clothing, studies were performed in which swatches of fabric impregnated with 14C-labeled permethrin were applied to the backs of rabbits for 1 wk. Permethrin migration was quantitated by measuring the fate of the 14C label. Conditions that could affect leaching and/or absorption were also evaluated, that is, varying environments, the presence of sweat, different fabric types, and the effects of prelaundering. Results showed that fabric treated with permethrin at a rate of 0.125 mg/cm2 lost the substance to the skin surface at an average rate of 0.49%/d. At the end of the 7-d exposures in rabbits, about 3.2% of the available permethrin had reached the skin, 2% having been recovered from excreta (absorbed) and 1.2% remaining on the skin surface. Prelaundering the treated fabric had little effect on migration rate, nor did the other variables tested. Exposure dose to humans from wearing permethrin-treated (0.125 mg/cm2) military clothing is predicted to be 6 x 10(-4) mg/kg/d.

Sweat-Related Dermatoses: Old Concept and New Scenario

This review focuses on dermatoses that are caused by the presence of sweat--a previously underemphasized subject. A working classification based on 'internal sweating' (extravasated sweat in the dermis and epidermis) and 'external sweating' (sweat on skin surface) is proposed. Clinical observations suggest that transient acantholytic dermatosis is the consequence of extravasated sweat; we speculate that it is an example of sweat-related, protease-induced epidermal acantholysis. Neutrophilic eccrine hidradenitis may represent a sweat-related drug reaction. We emphasize the well-recognized phenomenon of 'sweat retention syndrome' in a new scenario: hospitalized febrile patients, increasing use of chemotherapy, new life style. The concept of 'sweat-gland-mediated cutaneous inflammation' is proposed.

An Unusual Cause of Bromidrosis

Bromidrosis or osmidrosis is the term which denotes a malodrous condition of human perspiration. It is usually a local condition, but may be generalized. The most commonly encountered form of local bromidrosis results from the decomposition of organic matter on the skin surface via the enzymatic action of certain bacteria and/or fungi which thrive in the. presence of sweat. This decomposition alters the constituents of sweat, the lipids of the sebum, and the protein components of hydrated keratin. Generalized bromidrosis may have a variety of causes. It may come about due to substances present in the native sweat, or it may be "idiopathic" and caused by certain substances which normally are not present in the sweat or at best in small quantities.