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Sports Medicine (Auckland, N.Z.) Mar 2018In humans, thirst tends to be alleviated before complete rehydration is achieved. When sweating rates are high and ad libitum fluid consumption is not sufficient to... (Review)
Review
In humans, thirst tends to be alleviated before complete rehydration is achieved. When sweating rates are high and ad libitum fluid consumption is not sufficient to replace sweat losses, a cumulative loss in body water results. Body mass losses of 2% or greater take time to accumulate. Dehydration of ≥ 2% body mass is associated with impaired thermoregulatory function, elevated cardiovascular strain and, in many conditions (e.g., warmer, longer, more intense), impaired aerobic exercise performance. Circumstances where planned drinking is optimal include longer duration activities of > 90 min, particularly in the heat; higher-intensity exercise with high sweat rates; exercise where performance is a concern; and when carbohydrate intake of 1 g/min is desired. Individuals with high sweat rates and/or those concerned with exercise performance should determine sweat rates under conditions (exercise intensity, pace) and environments similar to that anticipated when competing and tailor drinking to prevent body mass losses > 2%. Circumstances where drinking to thirst may be sufficient include short duration exercise of < 1 h to 90 min; exercise in cooler conditions; and lower-intensity exercise. It is recommended to never drink so much that weight is gained.
Topics: Athletes; Dehydration; Drinking; Exercise; Humans; Sweating; Thirst; Water; Water-Electrolyte Balance
PubMed: 29368181
DOI: 10.1007/s40279-017-0844-6 -
Allergology International : Official... Jan 2021Cholinergic urticaria (CholU) manifests small, itchy and/or painful wheals occurring upon perspiration and mechanically involving acetylcholine (Ach). Although a... (Review)
Review
Cholinergic urticaria (CholU) manifests small, itchy and/or painful wheals occurring upon perspiration and mechanically involving acetylcholine (Ach). Although a considerable number of studies have been conducted, the pathomechanisms underlying perspiration-associated release of histamine remain to be elucidated. We have proposed that CholU can be categorized into two major subtypes: Ach-indirectly induced, sweat allergic type and Ach-directly induced, depressed sweating type. In the former type, Ach evokes perspiration, and some sweat antigen(s) leaking from the sweat ducts to the dermis may stimulate mast cells to release histamine. In this scenario, the ducts might be damaged or obstructed for sweat leakage, and patients frequently exhibit positive autologous sweat skin test, representing "sweat allergy (hypersensitivity)". On the other hand, the latter Ach-mast cell directly interacting type, typically seen as "CholU with anhidrosis and/or hypohidrosis (CUAH)", eccrine sweat gland epithelial cells lack cholinergic receptor M3 expression. The expression of cholinergic receptors is completely absent in the anhidrotic areas and only slightly expressed in the hypohidrotic areas. In the hypohidrotic area, where pinpoint wheal occurs, it is hypothesized that released Ach cannot be completely trapped by cholinergic receptors of eccrine glands and overflows to the adjacent mast cells, leading to wheal formation. Thus, sweat allergy is not a requirement in this depressed sweating type. Although some additional complications, such as angioedema, anaphylaxis, and cold urticaria, have been documented, these two types represent the modes of action of Ach in this enigmatic urticaria.
Topics: Acetylcholine; Allergens; Biomarkers; Disease Susceptibility; Gene Expression Regulation; Histamine; Histamine Release; Humans; Immunoglobulin E; Mast Cells; Receptors, Cholinergic; Skin Tests; Sweat; Urticaria
PubMed: 32565175
DOI: 10.1016/j.alit.2020.05.006 -
ACS Biomaterials Science & Engineering May 2023Sweat is an increasingly popular biological medium for fitness monitoring and clinical diagnostics. It contains an abundance of biological information and is available... (Review)
Review
Sweat is an increasingly popular biological medium for fitness monitoring and clinical diagnostics. It contains an abundance of biological information and is available continuously and noninvasively. Sweat-sensing devices often employ proteins in various capacities to create skin-friendly matrices that accurately extract valuable and time-sensitive information from sweat. Proteins were first used in sensors as biorecognition elements in the form of enzymes and antibodies, which are now being tuned to operate at ranges relevant for sweat. In addition, a range of structural proteins, sometimes assembled in conjunction with polymers, can provide flexible and compatible matrices for skin sensors. Other proteins also naturally possess a range of functionalities─as adhesives, charge conductors, fluorescence emitters, and power generators─that can make them useful components in wearable devices. Here, we examine the four main components of wearable sweat sensors─the biorecognition element, the transducer, the scaffold, and the adhesive─and the roles that proteins have played so far, or promise to play in the future, in each component. On a case-by-case basis, we analyze the performance characteristics of existing protein-based devices, their applicable ranges of detection, their transduction mechanism and their mechanical properties. Thereby, we review and compare proteins that can readily be used in sweat sensors and others that will require further efforts to overcome design, stability or scalability challenges. Incorporating proteins in one or multiple components of sweat sensors could lead to the development and deployment of tunable, greener, and safer biosourced devices.
Topics: Humans; Animals; Proteins; Sweat; Biosensing Techniques; Wearable Electronic Devices; Monitoring, Physiologic; Adhesiveness; Nanotechnology
PubMed: 34491052
DOI: 10.1021/acsbiomaterials.1c00699 -
ACS Applied Bio Materials Jan 2021The recent advent of biodegradable materials has offered huge opportunity to transform healthcare technologies by enabling sensors that degrade naturally after use. The... (Review)
Review
The recent advent of biodegradable materials has offered huge opportunity to transform healthcare technologies by enabling sensors that degrade naturally after use. The implantable electronic systems made from such materials eliminate the need for extraction or reoperation, minimize chronic inflammatory responses, and hence offer attractive propositions for future biomedical technology. The eco-friendly sensor systems developed from degradable materials could also help mitigate some of the major environmental issues by reducing the volume of electronic or medical waste produced and, in turn, the carbon footprint. With this background, herein we present a comprehensive overview of the structural and functional biodegradable materials that have been used for various biodegradable or bioresorbable electronic devices. The discussion focuses on the dissolution rates and degradation mechanisms of materials such as natural and synthetic polymers, organic or inorganic semiconductors, and hydrolyzable metals. The recent trend and examples of biodegradable or bioresorbable materials-based sensors for body monitoring, diagnostic, and medical therapeutic applications are also presented. Lastly, key technological challenges are discussed for clinical application of biodegradable sensors, particularly for implantable devices with wireless data and power transfer. Promising perspectives for the advancement of future generation of biodegradable sensor systems are also presented.
Topics: Biocompatible Materials; Biopolymers; Body Temperature; Breath Tests; Electrodes, Implanted; Humans; Monitoring, Physiologic; Pressure; Semiconductors; Sweat
PubMed: 33842859
DOI: 10.1021/acsabm.0c01139 -
Revue Medicale Suisse Jul 2021Sweat is a body fluid produced by the sweat glands and is mainly composed of water. Sweat has various functions, the two main ones being the evacuation of heat produced...
Sweat is a body fluid produced by the sweat glands and is mainly composed of water. Sweat has various functions, the two main ones being the evacuation of heat produced by the body, especially during exercise, and the maintenance of skin homeostasis. Its production is highly variable and depends on many individual and environmental factors. Various diseases or conditions affect its proper functioning. This article presents an overview of the characteristics, the main health issues, and the current and potential applications related to sweat.
Topics: Exercise; Hot Temperature; Humans; Skin; Sweat; Sweating
PubMed: 34264030
DOI: No ID Found -
Journal of the Royal Society, Interface Oct 2019The state-of-the-art in wearable flexible sensors (WFSs) for sweat analyte detection was investigated. Recent advances show the development of integrated, mechanically... (Review)
Review
The state-of-the-art in wearable flexible sensors (WFSs) for sweat analyte detection was investigated. Recent advances show the development of integrated, mechanically flexible and multiplexed sensor systems with on-site circuitry for signal processing and wireless data transmission. When compared with single-analyte sensors, such devices provide an opportunity to more accurately analyse analytes that are dependent on other parameters (such as sweat rate and pH) by improving calibration from real-time analysis, while maintaining a lightweight and wearable design. Important health conditions can be monitored and on-demand regulating drugs can be delivered using integrated wearable systems but require correlation verification between sweat and blood measurements using validation tests before any clinical application can be considered. Improvements are necessary for device sensitivity, accuracy and repeatability to provide more reliable and personalized continuous measurements. With rapid recent development, it can be concluded that non-invasive WFSs for sweat analysis have only skimmed the surface of their health monitoring potential and further significant advancement is sure to be made in the medical field.
Topics: Humans; Monitoring, Physiologic; Signal Processing, Computer-Assisted; Sweat; Wearable Electronic Devices
PubMed: 31594525
DOI: 10.1098/rsif.2019.0217 -
Biosensors & Bioelectronics Oct 2023Epidermal microfluidic devices are continuously being developed for efficient sweat collection and sweat rate detection. However, most microfluidic designs ignore the...
Epidermal microfluidic devices are continuously being developed for efficient sweat collection and sweat rate detection. However, most microfluidic designs ignore the use of airtight/adhesive substrate will block the natural perspiration of the covered sweat pores, which will seriously affect normal sweat production and long-term wearable comfort. Herein, we present a Janus textile-embedded microfluidic sensor platform with high breathability and directional sweat permeability for synchronous sweat rate and total electrolyte concentration detection. The device consists of a hollowed-out serpentine microchannel with interdigital electrodes and Janus textile. The dual-mode signal of the sweat rate (0.2-4.0 μL min) and total ionic charge concentration (10-200 mmol L) can be obtained synchronously by decoupling conductance step signals generated when sweat flows through alternating interdigitated spokes at equal intervals in the microchannel. Meanwhile, the hollowed-out microchannel structure significantly reduces the coverage area of the sensor on the skin, and the Janus textile-embedded device ensures a comfortable skin/device interface (fewer sweat pores are blocked) and improves breathability (503.15 g m d) and sweat permeability (directional liquid transportation) during long-term monitoring. This device is washable and reusable, which shows the potential to integrate with clothing and smart textile, and thus facilitate the practicality of wearable sweat sensors for personalized healthcare.
Topics: Sweat; Microfluidics; Biosensing Techniques; Electrolytes; Textiles
PubMed: 37406481
DOI: 10.1016/j.bios.2023.115504 -
Advanced Materials (Deerfield Beach,... Oct 2021A sweat sensor is expected to be the most appropriate wearable device for noninvasive healthcare monitoring. However, the practical use of sweat sensors is impeded by...
A sweat sensor is expected to be the most appropriate wearable device for noninvasive healthcare monitoring. However, the practical use of sweat sensors is impeded by irregular and low sweat secretion rates. Here, a sweat-collecting patch that can collect sweat efficiently for fast and continuous healthcare monitoring is demonstrated. The patch uses cactus-spine-inspired wedge-shaped wettability-patterned channels on a hierarchical microstructured/nanostructured surface. The channel shape, in combination with the superhydrophobic/superhydrophilic surface materials, induces a unidirectional Laplace pressure that transports the sweat to the sensing area spontaneously even when the patch is aligned vertically. The patch demonstrates superior sweat-collecting efficiency and reduces the time required to fill the sensing area by transporting sweat almost without leaving it inside the channel. Therefore, a sensor based on the patch responds quickly to biochemicals in sweat, and the patch enables the continuous monitoring of changes in sweat biochemicals according to their changes in the wearer's blood.
Topics: Biomimetics; Biosensing Techniques; Cactaceae; Humans; Microfluidics; Nanoparticles; Polyvinyl Alcohol; Silicon Dioxide; Skin; Surface Properties; Sweat; Wearable Electronic Devices; Wettability
PubMed: 34396596
DOI: 10.1002/adma.202102740 -
Nature Reviews. Chemistry Dec 2022Biomarkers are crucial biological indicators in medical diagnostics and therapy. However, the process of biomarker discovery and validation is hindered by a lack of... (Review)
Review
Biomarkers are crucial biological indicators in medical diagnostics and therapy. However, the process of biomarker discovery and validation is hindered by a lack of standardized protocols for analytical studies, storage and sample collection. Wearable chemical sensors provide a real-time, non-invasive alternative to typical laboratory blood analysis, and are an effective tool for exploring novel biomarkers in alternative body fluids, such as sweat, saliva, tears and interstitial fluid. These devices may enable remote at-home personalized health monitoring and substantially reduce the healthcare costs. This Review introduces criteria, strategies and technologies involved in biomarker discovery using wearable chemical sensors. Electrochemical and optical detection techniques are discussed, along with the materials and system-level considerations for wearable chemical sensors. Lastly, this Review describes how the large sets of temporal data collected by wearable sensors, coupled with modern data analysis approaches, would open the door for discovering new biomarkers towards precision medicine.
Topics: Wearable Electronic Devices; Biosensing Techniques; Body Fluids; Sweat; Biomarkers
PubMed: 37117704
DOI: 10.1038/s41570-022-00439-w -
Sensors (Basel, Switzerland) Oct 2022Sweat analysis offers non-invasive real-time on-body measurement for wearable sensors. However, there are still gaps in current developed sweat-sensing devices (SSDs)... (Review)
Review
Sweat analysis offers non-invasive real-time on-body measurement for wearable sensors. However, there are still gaps in current developed sweat-sensing devices (SSDs) regarding the concerns of mixing fresh and old sweat and real-time measurement, which are the requirements to ensure accurate the measurement of wearable devices. This review paper discusses these limitations by aiding model designs, features, performance, and the device operation for exploring the SSDs used in different sweat collection tools, focusing on continuous and non-continuous flow sweat analysis. In addition, the paper also comprehensively presents various sweat biomarkers that have been explored by earlier works in order to broaden the use of non-invasive sweat samples in healthcare and related applications. This work also discusses the target analyte's response mechanism for different sweat compositions, categories of sweat collection devices, and recent advances in SSDs regarding optimal design, functionality, and performance.
Topics: Biomarkers; Biosensing Techniques; Monitoring, Physiologic; Sweat; Wearable Electronic Devices
PubMed: 36236769
DOI: 10.3390/s22197670