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ACS Applied Materials & Interfaces Nov 2020Metal-based antiperspirants have been in use for centuries; however, there is an increasing consumer demand for a metal-free alternative that works effectively. Here, we...
Metal-based antiperspirants have been in use for centuries; however, there is an increasing consumer demand for a metal-free alternative that works effectively. Here, we develop an artificial sweat duct rig and demonstrate an alternative, metal-free approach to antiperspiration. Instead of clogging sweat ducts with metal salts, we use a hygroscopic material to induce the evaporation of sweat as it approaches the outlet (i.e. pore) of the sweat duct. As a result, the sweat dehydrates almost completely while still being inside of the duct, forming a natural gel-like salt plug that halts the flow. We show that the critical pressure gradient within the duct (∼3 kPa), beneath which clogging occurs, can be rationalized by balancing the mass flow rates of the liquid (Poiseuille's law) and the evaporative vapor (Fick's law).
Topics: Antiperspirants; Artificial Organs; Metals; Pressure; Salts; Sweat; Sweating
PubMed: 33191727
DOI: 10.1021/acsami.0c13493 -
Sports Medicine (Auckland, N.Z.) Oct 2016Numerous studies have reported on the thermoregulation and hydration challenges athletes face in team and individual sports during exercise in the heat. Comparatively... (Review)
Review
Numerous studies have reported on the thermoregulation and hydration challenges athletes face in team and individual sports during exercise in the heat. Comparatively less research, however, has been conducted on the American Football player. Therefore, the purpose of this article is to review data collected in laboratory and field studies and discuss the thermoregulation, fluid balance, and sweat losses of American Football players. American Football presents a unique challenge to thermoregulation compared with other sports because of the encapsulating nature of the required protective equipment, large body size of players, and preseason practice occurring during the hottest time of year. Epidemiological studies report disproportionately higher rates of exertional heat illness and heat stroke in American Football compared with other sports. Specifically, larger players (e.g., linemen) are at increased risk for heat ailments compared with smaller players (e.g., backs) because of greater body mass index, increased body fat, lower surface area to body mass ratio, lower aerobic capacity, and the stationary nature of the position, which can reduce heat dissipation. A consistent finding across studies is that larger players exhibit higher sweating rates than smaller players. Mean sweating rates from 1.0 to 2.9 L/h have been reported for college and professional American Football players, with several studies reporting 3.0 L/h or more in some larger players. Sweat sodium concentration of American Football players does not seem to differ from that of athletes in other sports; however, given the high volume of sweat loss, the potential for sodium loss is higher in American Football than in other sports. Despite high sweating rates with American Football players, the observed disturbances in fluid balance have generally been mild (mean body mass loss ≤2 %). The majority of field-based studies have been conducted in the northeastern part of the United States, with limited studies in different geographical regions (i.e., southeast) of the United States. Further, there have been a limited number of studies examining body core temperature of American Football players during preseason practice, especially at the high school level. Future field-based research in American Football with various levels of competition in hotter geographical regions of the United States is warranted.
Topics: Body Size; Body Temperature Regulation; Football; Heat Stress Disorders; Humans; Male; Protective Clothing; Risk Factors; Sodium; Sweat; Sweating; United States; Water-Electrolyte Balance
PubMed: 27071988
DOI: 10.1007/s40279-016-0527-8 -
Dermatology (Basel, Switzerland) 2014The skin excretes substances primarily through sweat glands. Several conditions have been demonstrated to be associated with diminished sweating. However, few studies... (Review)
Review
The skin excretes substances primarily through sweat glands. Several conditions have been demonstrated to be associated with diminished sweating. However, few studies have concentrated on the metabolism and excretion of sweat. This review focuses on the relationship between temperature and the thermoregulatory efficacy of sweat, and then discusses the excretion of sweat, which includes the metabolism of water, minerals, proteins, vitamins as well as toxic substances. The potential role of sweat secretion in hormone homeostasis and the effects on the defense system of the skin are also clarified.
Topics: Body Temperature Regulation; Humans; Immunoglobulin A, Secretory; Immunologic Factors; Skin; Sweat; Sweat Glands; Sweating
PubMed: 24577280
DOI: 10.1159/000357524 -
Lab on a Chip May 2023Research targeting the development of on-body sensors has been significantly growing in recent years - an example is on-skin sweat sensing. However, the wide inter and...
Research targeting the development of on-body sensors has been significantly growing in recent years - an example is on-skin sweat sensing. However, the wide inter and intra person variability of skin characteristics make testing of these sensors and included materials such as skin adhesives difficult, which hampers especially the initial development phase of such wearables. Besides the development of wearable sweat sensors, companies developing deodorants, cosmetics, medical adhesives and wearable textiles now need to perform expensive human subjects testing with little control over the exact sweat mechanisms. Hence, there is a need for a realistic, adaptable and stable test platform, or artificial skin. We present a versatile artificial skin platform that faithfully recapitulates skin topography, active sweat pores, skin wetting behaviour and sweat rate, and that can be tuned to mimic the specifications of the targeted body location and sweating characteristics. The developed artificial skin is capable of generating sweat rates as low as 0.1 nL min pore and as high as 100 nL min pore, spanning the whole range of physiological sweat rates. Specifically, the platform can be used for the development of sweat sensors for sedentary persons whose sweat rates are commonly lower than currently delivered by any other artificial skin platform.
Topics: Humans; Sweating; Sweat; Skin, Artificial; Skin; Biosensing Techniques
PubMed: 37043225
DOI: 10.1039/d3lc00109a -
Environmental Science & Technology Apr 2024Sweating regulates the body temperature in extreme environments or during exercise. Here, we investigate the evaporative heat transfer of a sweat droplet at the...
Sweating regulates the body temperature in extreme environments or during exercise. Here, we investigate the evaporative heat transfer of a sweat droplet at the microscale to unveil how the evaporation complexity of a sweat droplet would affect the body's ability to cool under specific environmental conditions. Our findings reveal that, depending on the relative humidity and temperature levels, sweat droplets experience imperfect evaporation dynamics, whereas water droplets evaporate perfectly at equivalent ambient conditions. At low humidity, the sweat droplet fully evaporates and leaves a solid deposit, while at high humidity, the droplet never reaches a solid deposit and maintains a liquid phase residue for both low and high temperatures. This unprecedented evaporation mechanism of a sweat droplet is attributed to the intricate physicochemical properties of sweat as a biofluid. We suppose that the sweat residue deposited on the surface by evaporation is continuously absorbing the surrounding moisture. This route leads to reduced evaporative heat transfer, increased heat index, and potential impairment of the body's thermoregulation capacity. The insights into the evaporative heat transfer dynamics at the microscale would help us to improve the knowledge of the body's natural cooling mechanism with practical applications in healthcare, materials science, and sports science.
Topics: Sweating; Sweat; Hot Temperature; Body Temperature Regulation; Temperature
PubMed: 38538556
DOI: 10.1021/acs.est.4c00850 -
Annals of Agricultural and... Sep 2018One possible way of iron loss is sweating. It is unclear how physical activity performed by untrained individuals affects the iron status in sweat.
INTRODUCTION
One possible way of iron loss is sweating. It is unclear how physical activity performed by untrained individuals affects the iron status in sweat.
OBJECTIVE
The purpose of this study was to analyse iron concentration in sweat during 4-week exercise training to determine the changes in iron excretion during follow-up exercises.
MATERIAL AND METHODS
43 untrained volunteers participated in the study, 29 of whom completed the full exercise programme. The training programme consisted of exercises on a cycle ergometer and cross-trainer. In the first week, participants exercised for 8 minutes on each device, in the second for 10 minutes, and in the third and fourth weeks they exercised for 15 min on each device. Intensity was submaximal and defined as 85% of maximal heart rate. A sterile sweat patch was placed on the skin between shoulder blades.
RESULTS
Concentration of iron on the first and the fifteenth day of exercises was comparable and statistically insignificant. Iron concentration was highly increased on the last day of training in comparison with first (p<0.001) and fourteenth day (p<0.006). The median of iron concentration in 29 samples on the first day of sampling was 21.2 ppb, in the fifteenth - 52.5 ppb, and on the twenty-eighth day - 286.2 ppb. In relation with the sodium concentration, the iron content was also increased on the twenty-eighth day of the training programme (p<0.005).
CONCLUSIONS
Iron sweat loss significantly increased during the 4-week exercise programme. A possible explanation may be improvement in the thermoregulation mechanism and secretory activity of sweat glands. Iron sweat loss may be an indicator of iron deficiency observed in active individuals.
Topics: Adult; Exercise; Female; Humans; Iron; Middle Aged; Sweat; Sweating; Young Adult
PubMed: 30260183
DOI: 10.26444/aaem/78787 -
Journal of Applied Physiology... Aug 2018By combining galvanic skin conductance (GSC), stratum corneum hydration (HYD) and regional surface sweat rate (RSR) measurements at the arm, thigh, back and chest, we...
By combining galvanic skin conductance (GSC), stratum corneum hydration (HYD) and regional surface sweat rate (RSR) measurements at the arm, thigh, back and chest, we closely monitored the passage of sweat from gland to skin surface. Through a varied exercise-rest protocol, sweating was increased slowly and decreased in 16 male and female human participants (25.3 ± 4.7 yr, 174.6 ± 10.1 cm, 71.3 ± 12.0 kg, 53.0 ± 6.8 ml·kg·min). ∆GSC and HYD increased before RSR, indicating pre-secretory sweat gland activity and skin hydration. ∆GSC and HYD typically increased concomitantly during rest in a warm environment (30.1 ± 1.0°C, 30.0 ± 4.7% relative humidity) and only at the arm did ∆GSC increase before an increase in HYD. HYD increased before RSR, before sweat was visible on the skin, but not to full saturation, contradicting earlier hypotheses. Maximal skin hydration did occur, as demonstrated by a plateau in all regions. Post exercise rest resulted in a rapid decrease in HYD and RSR but a delayed decline in ∆GSC. Evidence for reabsorption of surface sweat into the skin following a decline in sweating, as hypothesized in the literature, was not found. This suggests that skin surface sweat, after sweating is decreased, may not diffuse back into the dermis, but is only evaporated. These data, showing distinctly different responses for the three measured variables, provide useful information about the fate of sweat from gland to surface that is relevant across numerous research fields (e.g., thermoregulation, dermatology, ergonomics and material design). NEW & NOTEWORTHY After sweat gland stimulation, sweat travels through the duct, penetrating the epidermis before appearing on the skin surface. We found that only submaximal stratum corneum hydration was required before surface sweating occurred. However, full hydration occurred only once sweat was on the surface. Once sweating reduces, surface sweat evaporation continues, but there is a delayed drying of the skin. This information is relevant across various research fields, including environmental ergonomics, dermatology, thermoregulation, and skin-interface interactions.
Topics: Adult; Body Temperature Regulation; Exercise; Female; Humans; Male; Rest; Skin; Skin Absorption; Skin Physiological Phenomena; Skin Temperature; Sweat; Sweat Glands; Sweating
PubMed: 29745799
DOI: 10.1152/japplphysiol.00872.2017 -
Blood Feb 2013
Topics: Adolescent; Female; Hemorrhage; Humans; Skin Diseases; Sweat; Sweat Gland Diseases; Sweating
PubMed: 23570065
DOI: 10.1182/blood-2012-09-450031 -
Analytical Chemistry May 2022Sweat sensors allow for new unobtrusive ways to continuously monitor an athlete's performance and health status. Significant advances have been made in the optimization...
Sweat sensors allow for new unobtrusive ways to continuously monitor an athlete's performance and health status. Significant advances have been made in the optimization of sensitivity, selectivity, and durability of electrochemical sweat sensors. However, comparing the performance of these sensors in detail remains challenging because standardized sweat measurement methods to validate sweat sensors in a physiological setting do not yet exist. Current collection methods, such as the absorbent patch technique, are prone to contamination and are labor-intensive, which limits the number of samples that can be collected over time for offline reference measurements. We present an easy-to-fabricate sweat collection system that allows for continuous electrochemical monitoring, as well as chronological sampling of sweat for offline analysis. The patch consists of an analysis chamber hosting a conductivity sensor and a sequence of 5 to 10 reservoirs that contain level indicators that monitor the filling speed. After testing the performance of the patch in the laboratory, elaborate physiological validation experiments (3 patch locations, 6 participants) were executed. The continuous sweat conductivity measurements were compared with laboratory [Na] and [Cl] measurements of the samples, and a strong linear relationship ( = 0.97) was found. Furthermore, sweat rate derived from ventilated capsule measurement at the three locations was compared with patch filling speed and continuous conductivity readings. As expected from the literature, sweat conductivity was linearly related to sweat rate as well. In short, a successfully validated sweat collection patch is presented that enables sensor developers to systematically validate novel sweat sensors in a physiological setting.
Topics: Biosensing Techniques; Humans; Ions; Monitoring, Physiologic; Sweat; Sweating; Wearable Electronic Devices
PubMed: 35486709
DOI: 10.1021/acs.analchem.2c01052 -
The Journal of Thoracic and... Oct 2018
Topics: Humans; Hyperhidrosis; Sweat; Sweating; Sympathectomy
PubMed: 30248806
DOI: 10.1016/j.jtcvs.2018.07.055