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Biosensors Oct 2022Wearable sensors and invasive devices have been studied extensively in recent years as the demand for real-time human healthcare applications and seamless human-machine... (Review)
Review
Wearable sensors and invasive devices have been studied extensively in recent years as the demand for real-time human healthcare applications and seamless human-machine interaction has risen exponentially. An explosion in sensor research throughout the globe has been ignited by the unique features such as thermal, electrical, and mechanical properties of graphene. This includes wearable sensors and implants, which can detect a wide range of data, including body temperature, pulse oxygenation, blood pressure, glucose, and the other analytes present in sweat. Graphene-based sensors for real-time human health monitoring are also being developed. This review is a comprehensive discussion about the properties of graphene, routes to its synthesis, derivatives of graphene, etc. Moreover, the basic features of a biosensor along with the chemistry of sweat are also discussed in detail. The review mainly focusses on the graphene and its derivative-based wearable sensors for the detection of analytes in sweat. Graphene-based sensors for health monitoring will be examined and explained in this study as an overview of the most current innovations in sensor designs, sensing processes, technological advancements, sensor system components, and potential hurdles. The future holds great opportunities for the development of efficient and advanced graphene-based sensors for the detection of analytes in sweat.
Topics: Humans; Sweat; Graphite; Wearable Electronic Devices; Monitoring, Physiologic; Biosensing Techniques; Glucose
PubMed: 36291046
DOI: 10.3390/bios12100910 -
Biosensors Jan 2023The current physical health care system has gradually evolved into a form of virtual hospitals communicating with sensors, which can not only save time but can also... (Review)
Review
The current physical health care system has gradually evolved into a form of virtual hospitals communicating with sensors, which can not only save time but can also diagnose a patient's physical condition in real time. Textile-based wearable sensors have recently been identified as detection platforms with high potential. They are developed for the real-time noninvasive detection of human physiological information to comprehensively analyze the health status of the human body. Sweat comprises various chemical compositions, which can be used as biomarkers to reflect the relevant information of the human physiology, thus providing references for health conditions. Combined together, textile-based sweat sensors are more flexible and comfortable than other conventional sensors, making them easily integrated into the wearable field. In this short review, the research progress of textile-based flexible sweat sensors was reviewed. Three mechanisms commonly used for textile-based sweat sensors were firstly contrasted with an introduction to their materials and preparation processes. The components of textile-based sweat sensors, which mainly consist of a sweat transportation channel and collector, a signal-selection unit, sensing elements and sensor integration and communication technologies, were reviewed. The applications of textile-based sweat sensors with different mechanisms were also presented. Finally, the existing problems and challenges of sweat sensors were summarized, which may contribute to promote their further development.
Topics: Humans; Sweat; Wearable Electronic Devices; Textiles; Biomarkers
PubMed: 36671962
DOI: 10.3390/bios13010127 -
International Journal of Sport... Sep 2022The purpose of this study was to compare a wearable microfluidic device and standard absorbent patch in measuring local sweating rate (LSR) and sweat chloride...
The purpose of this study was to compare a wearable microfluidic device and standard absorbent patch in measuring local sweating rate (LSR) and sweat chloride concentration ([Cl-]) in elite basketball players. Participants were 53 male basketball players (25 ± 3 years, 92.2 ± 10.4 kg) in the National Basketball Association's development league. Players were tested during a moderate-intensity, coach-led practice (98 ± 30 min, 21.0 ± 1.2 °C). From the right ventral forearm, sweat was collected using an absorbent patch (3M Tegaderm™ + Pad). Subsequently, LSR and local sweat [Cl-] were determined via gravimetry and ion chromatography. From the left ventral forearm, LSR and local sweat [Cl-] were measured using a wearable microfluidic device and associated smartphone application-based algorithms. Whole-body sweating rate (WBSR) was determined from pre- to postexercise change in body mass corrected for fluid/food intake (ad libitum), urine loss, and estimated respiratory water and metabolic mass loss. The WBSR values predicted by the algorithms in the smartphone application were also recorded. There were no differences between the absorbent patch and microfluidic patch for LSR (1.25 ± 0.91 mg·cm-2·min-1 vs. 1.14 ±0.78 mg·cm-2·min-1, p = .34) or local sweat [Cl-] (30.6 ± 17.3 mmol/L vs. 29.6 ± 19.4 mmol/L, p = .55). There was no difference between measured and predicted WBSR (0.97 ± 0.41 L/hr vs. 0.89 ± 0.35 L/hr, p = .22; 95% limits of agreement = 0.61 L/hr). The wearable microfluidic device provides similar LSR, local sweat [Cl-], and WBSR results compared with standard field-based methods in elite male basketball players during moderate-intensity practices.
Topics: Basketball; Chlorides; Humans; Lab-On-A-Chip Devices; Male; Microfluidics; Sweat; Sweating; Wearable Electronic Devices
PubMed: 35477899
DOI: 10.1123/ijsnem.2022-0017 -
Molecules (Basel, Switzerland) Jun 2023Sweat, a biofluid secreted naturally from the eccrine glands of the human body, is rich in several electrolytes, metabolites, biomolecules, and even xenobiotics that... (Review)
Review
Sweat, a biofluid secreted naturally from the eccrine glands of the human body, is rich in several electrolytes, metabolites, biomolecules, and even xenobiotics that enter the body through other means. Recent studies indicate a high correlation between the analytes' concentrations in the sweat and the blood, opening up sweat as a medium for disease diagnosis and other general health monitoring applications. However, low concentration of analytes in sweat is a significant limitation, requiring high-performing sensors for this application. Electrochemical sensors, due to their high sensitivity, low cost, and miniaturization, play a crucial role in realizing the potential of sweat as a key sensing medium. MXenes, recently developed anisotropic two-dimensional atomic-layered nanomaterials composed of early transition metal carbides or nitrides, are currently being explored as a material of choice for electrochemical sensors. Their large surface area, tunable electrical properties, excellent mechanical strength, good dispersibility, and biocompatibility make them attractive for bio-electrochemical sensing platforms. This review presents the recent progress made in MXene-based bio-electrochemical sensors such as wearable, implantable, and microfluidic sensors and their applications in disease diagnosis and developing point-of-care sensing platforms. Finally, the paper discusses the challenges and limitations of MXenes as a material of choice in bio-electrochemical sensors and future perspectives on this exciting material for sweat-sensing applications.
Topics: Humans; Wearable Electronic Devices; Sweat; Biosensing Techniques; Nanostructures
PubMed: 37375172
DOI: 10.3390/molecules28124617 -
Clinical Autonomic Research : Official... Apr 2009Sudomotor dysfunction is common in many subtypes of neuropathy but is one of the earliest detectable neurophysiologic abnormalities in distal small fiber neuropathy.... (Review)
Review
Sudomotor dysfunction is common in many subtypes of neuropathy but is one of the earliest detectable neurophysiologic abnormalities in distal small fiber neuropathy. Clinical assessments of sudomotor function include thermoregulatory sweat testing (TST), quantitative sudomotor axon reflex testing (QSART), silicone impressions, the sympathetic skin response (SSR), the acetylcholine sweat-spot test and quantitative direct and indirect axon reflex testing (QDIRT). These testing techniques, when used in combination, can detect and localize pre- and postganglionic lesions, can provide early diagnosis of sudomotor dysfunction and can monitor disease progression or disease recovery. In this article, we describe many of the common clinical tests available for evaluation of sudomotor function with focus on the testing methodology and limitations while providing concrete examples of test results.
Topics: Acetylcholine; Diagnostic Techniques, Neurological; Humans; Peripheral Nervous System Diseases; Reflex; Sweat; Sweating
PubMed: 18989618
DOI: 10.1007/s10286-008-0506-8 -
Physiology & Behavior Oct 2023Humans produce odorous secretions from multiple body sites according to the microbiomic profile of each area and the types of secretory glands present. Because the... (Review)
Review
Humans produce odorous secretions from multiple body sites according to the microbiomic profile of each area and the types of secretory glands present. Because the axilla is an active, odor-producing region that mediates social communication via the sense of smell, this article focuses on the biological mechanisms underlying the creation of axillary odor, as well as the intrinsic and extrinsic factors likely to impact the odor and determine individual differences. The list of intrinsic factors discussed includes sex, age, ethnicity, emotions, and personality, and extrinsic factors include dietary choices, diseases, climate, and hygienic habits. In addition, we also draw attention to gaps in our understanding of each factor, including, for example, topical areas such as the effect of climate on body odor variation. Fundamental challenges and emerging research opportunities are further outlined in the discussion. Finally, we suggest guidelines and best practices based on the factors reviewed herein for preparatory protocols of sweat collection, data analysis, and interpretation.
Topics: Humans; Odorants; Sweat; Smell; Sweating; Axilla
PubMed: 37516230
DOI: 10.1016/j.physbeh.2023.114307 -
Experimental Physiology Dec 2019What is the central question of this study? What is the role of nicotinic receptors in the regulation of normothermic cutaneous blood flow and cutaneous vasodilatation...
NEW FINDINGS
What is the central question of this study? What is the role of nicotinic receptors in the regulation of normothermic cutaneous blood flow and cutaneous vasodilatation and sweating during whole-body heating induced following resting in a non-heat-stress condition? What is the main finding and its importance? Nicotinic receptors modulated cutaneous vascular tone during rest in a non-heat-stress condition and in the early stage of heating, but they had a limited role in mediating cutaneous vasodilatation when core temperature increased >0.4°C. Further, the contribution of nicotinic receptors to sweating was negligible during whole-body heating. Our findings provide new insights into the role of nicotinic receptors in end-organ function of skin vasculature and sweat glands in humans.
ABSTRACT
Nicotinic receptors are present in human skin including cutaneous vessels and eccrine sweat glands as well as peripheral nerves. We tested the hypothesis that nicotinic receptors do not contribute to the control of cutaneous vascular tone in the normothermic state, but are involved in mediating cutaneous vasodilatation and sweating during a whole-body passive heat stress in humans. We first performed a nicotinic receptor blocker verification protocol in six young adults (one female) wherein increases in cutaneous vascular conductance and sweating elicited by 10 mm nicotine were blocked by administration of 500 µm hexamethonium to confirm effective blockade. Thereafter, 12 young males participated in a passive heating protocol. After an instrumentation period in a non-heat-stress condition, participants rested for a 10 min baseline period. Thereafter, oesophageal temperature was increased by 1.0°C using water-perfusion suits. Cutaneous vascular conductance, sweat rate, active sweat gland density and sweat output per individual gland were assessed with and without 500 µm hexamethonium administered via intradermal microdialysis. Hexamethonium reduced cutaneous vascular conductance by 22-34% during normothermia and the early stage of heating. However, this effect was diminished as oesophageal temperature increased >0.4°C. Active sweat gland density was reduced by hexamethonium when oesophageal temperature was elevated by 0.4-0.6°C above baseline resting. However, this was paralleled by a marginal increase in sweat gland output. Consequently, sweat rate remained unchanged. We showed that nicotinic receptors modulate cutaneous perfusion during normothermia and the early stage of heating, but not when core temperature increases >0.4°C. Additionally, they play a limited role in mediating sweating during heating.
Topics: Adult; Fever; Hot Temperature; Humans; Male; Microdialysis; Nicotine; Nicotinic Agonists; Receptors, Nicotinic; Skin; Skin Physiological Phenomena; Sweating; Vasodilation; Young Adult
PubMed: 31608521
DOI: 10.1113/EP088072 -
Experimental Physiology Feb 2020What is the central question of this study? We evaluated whether regional variations exist in NO-dependent cutaneous vasodilatation and sweating during cholinergic...
NEW FINDINGS
What is the central question of this study? We evaluated whether regional variations exist in NO-dependent cutaneous vasodilatation and sweating during cholinergic stimulation. What is the main finding and its importance? Peak cutaneous vasodilatation and sweating were greater on the torso than the forearm. Furthermore, we found that NO was an important modulator of cholinergic cutaneous vasodilatation, but not sweating, across body regions, with a greater contribution of NO to cutaneous vasodilatation in the limb compared with the torso. These findings advance our understanding of the mechanisms influencing regional variations in cutaneous vasodilator and sweating responses to pharmacological stimulation.
ABSTRACT
Regional variations in cutaneous vasodilatation and sweating exist across the body. Nitric oxide (NO) is an important modulator of these heat loss responses in the forearm. However, whether regional differences in NO-dependent cutaneous vasodilatation and sweating exist remain uncertain. In 14 habitually active young men (23 ± 4 years of age), cutaneous vascular conductance (CVC ) and local sweat rates were assessed at six skin sites. On each of the dorsal forearm, chest and upper back (trapezius), sites were continuously perfused with either lactated Ringer solution (control) or 10 mm N -nitro-l-arginine (l-NNA; an NO synthase inhibitor) dissolved in Ringer solution, via microdialysis. At all sites, cutaneous vasodilatation and sweating were induced by co-administration of the cholinergic agonist methacholine (1, 10, 100, 1000 and 2000 mm; 25 min per dose) followed by 50 mm sodium nitroprusside (20-25 min) to induce maximal vasodilatation. The l-NNA attenuated CVC relative to the control conditions for all regions (all P < 0.05), and NO-dependent vasodilatation was greater at the forearm compared with the back and chest (both P < 0.05). Furthermore, maximal vasodilatation was higher at the back and chest relative to the forearm (both P < 0.05). Conversely, l-NNA had negligible effects on sweating across the body (all P > 0.05). Peak local sweat rate was higher at the back relative to the forearm (P < 0.05), with a similar trend observed for the chest. In habitually active young men, NO-dependent cholinergic cutaneous vasodilatation varied across the body, and the contribution to cholinergic sweating was negligible. These findings advance our understanding of the mechanisms influencing regional variations in cutaneous vasodilatation and sweating during pharmacological stimulation.
Topics: Adult; Dose-Response Relationship, Drug; Enzyme Inhibitors; Humans; Injections, Subcutaneous; Male; Methacholine Chloride; Muscarinic Agonists; Nitric Oxide Synthase; Nitroarginine; Skin; Sweating; Vasodilation; Young Adult
PubMed: 31821642
DOI: 10.1113/EP088295 -
Scientific Reports Dec 2021Inconsistent results were found throughout the literature regarding factors affecting hair cortisol levels. Hair cortisol level in humans was not studied for its... (Comparative Study)
Comparative Study
Inconsistent results were found throughout the literature regarding factors affecting hair cortisol levels. Hair cortisol level in humans was not studied for its associations to scalp hair sweating or hair wash frequency in a patient-based way. Factors affecting hair cortisol levels must be precisely known in order to interpret the results correctly. The aims of the study are to assess if BMI, Perceived Stress Scale (PSS), hair wash frequency, and sweating with scalp hair affect hair cortisol levels. It will assess which of these factors are more significant predictors of hair cortisol levels. In a study on healthy adults, information about history, socio-demographics, PSS, hair wash frequency, hair treatment, and scalp hair sweating were collected, and hair samples were taken and analyzed for their hair cortisol level. Associations of hair cortisol levels with each of the variables were investigated and significant predictors of hair cortisol levels among the variables were found. Mean hair cortisol level in the study participants was 16.84 pg/mg hair. Hair cortisol has a significant positive association with weight, BMI, PSS, and scalp hair sweating, p < 0.05. Scalp hair sweating significantly predicts hair cortisol levels by 12.3%, while other variables did not significantly predict hair cortisol levels, p < 0.05. Scalp hair sweating significantly predicts hair cortisol levels. Age, hair wash frequency, hair treatment, and stressful events have no associations with hair cortisol levels. Although BMI and PSS are associated with hair cortisol levels, they do not significantly predict it. Obesity is significantly associated with profuse sweating, thus the increase in hair cortisol levels in obese individuals could partly be the result of a higher incidence of sweating in these individuals. Thus, scalp hair sweating should be taken into consideration during the study and interpretation of hair cortisol levels.
Topics: Adolescent; Adult; Aged; Female; Hair; Humans; Hydrocortisone; Male; Middle Aged; Obesity; Prospective Studies; Scalp; Sweat; Sweating
PubMed: 34921159
DOI: 10.1038/s41598-021-02223-0 -
Nutrients Nov 2022Physiological and biological markers in different body fluids are used to measure the body's physiological or pathological status. In the field of sports and exercise... (Review)
Review
Physiological and biological markers in different body fluids are used to measure the body's physiological or pathological status. In the field of sports and exercise medicine, the use of these markers has recently become more popular for monitoring an athlete's training response and assessing the immediate or long-term effects of exercise. Although the effect of exercise on different physiological markers using various body fluids is well substantiated, no article has undertaken a review across multiple body fluids such as blood, saliva, urine and sweat. This narrative review aims to assess various physiological markers in blood, urine and saliva, at rest and after exercise and examines physiological marker levels obtained across similar studies, with a focus on the population and study methodology used. Literature searches were conducted using PRISMA guidelines for keywords such as exercise, physical activity, serum, sweat, urine, and biomarkers, resulting in an analysis of 15 studies for this review paper. When comparing the effects of exercise on physiological markers across different body fluids (blood, urine, and saliva), the changes detected were generally in the same direction. However, the extent of the change varied, potentially as a result of the type and duration of exercise, the sample population and subject numbers, fitness levels, and/or dietary intake. In addition, none of the studies used solely female participants; instead, including males only or both male and female subjects together. The results of some physiological markers are sex-dependent. Therefore, to better understand how the levels of these biomarkers change in relation to exercise and performance, the sex of the participants should also be taken into consideration.
Topics: Humans; Male; Female; Exercise; Sports; Body Fluids; Sweat; Biomarkers
PubMed: 36364948
DOI: 10.3390/nu14214685