We review various methods developed for human perspiration measurement and their physiological applications, with special reference to the performance and application of a new home-made ratemeter and instrumentation with a microscope. Many kinds of humidity sensor based on humidity-sensitive electrical properties have been investigated and placed on the market. Recently a capacitive thin-film humidity sensor was constructed and confirmed to be one of the best humidity sensors for accurately and quickly detecting changes in the relative humidity of gas-dow perfused through a ventilated chamber for human perspiration measurement. In this paper we also introduce a new home-made ratemeter with a capacitive humidity sensor, the electrical output of which is not disturbed by changes in ambient temperature, and new instrumentation for directly observing drops of sweat secreted from eccrine glands in human skin and simultaneously measuring the change in amount of perspiration at the same area of skin. Finally, we review physiological applications of the methods for measuring human palmar perspiration including emotional sweating.
Background Some methodologies used for evaluating sweat production and antiperspirants are of a stationary aspect, that is, most often performed under warm (38°C) but resting conditions in a rather short period of time. The aim is to develop an electronic sensor apt at continuously recording sweat excretion, in vivo, during physical exercises, exposure to differently heated environments, or any other stimuli that may provoke sweat excretion. Material and Methods A sensor (20 cm2) is wrapped under a double‐layered textile pad. Fixed onto the armpits, these two arrays of electrodes are connected to electronic system through an analog multiplexer. A microcontroller is used to permanently record changes in the conductance between two electrodes during exposure of subjects to different sweat‐inducing conditions or to assess the efficacy of applied aluminum hydrochloride (ACH)‐based roll‐ons at two concentrations (5% and 15%). Results In vitro calibration, using a NaCl 0.5% solution, allows changes in mV to be related with progressively increased volumes. In vivo, results show that casual physical exercise leads to sweat excretions much higher than in warm environment (37 or 45°C). Only, an exposure to a 50°C environment induced comparable sweat excretion. In this condition, sweat excretions were found similar in both armpits and both genders. Decreased sweat excretions were recorded following applications of ACH, with a dose effect. Conclusion Developing phases of this new approach indicate that usual method or guidelines used to determine sweat excretions in vivo do not reflect true energy expenditure processes. As a consequence, they probably over‐estimate the efficacy of antiperspirant agents or formulae.
Abstract Sweating measurement is a very useful tool for the physiological health state of the human body. A sweating measuring system developed in this study was composed of several sensors. All sensors were calibrated to ensure the accuracy. Three pretreatment physiological states for test subjects before sweating measurement included sit and rest for 5 min, walking for 5 min, and running for 5 min. The whole sweating value was measured and calculated over 5-min periods. The results of sweating measurement indicated the usefulness of this device. The sweating quantity of three states did not have a significant relationship with the height, weight and body mass index (BMI) values of subjects. The first sweating index is the difference between active treatment and sitting state. The second sweating index is the ratio between active state and sitting. The relationship between two sweating index and BMI values could be found. This device could serve as a detecting tool to establish the sweating database for normal conditions and to be used for diagnosis.
Homeowners and professional applicators frequently use chemicals to control insect pests in urban environments. The identification and evaluation of determinants of human exposure are critical to conduct reliable and responsible human exposure assessments following indoor residential chemical applications. The effect of sweat on absorbed dose in humans was evaluated with human volunteers who participated in a structured activity program ( SAP). Participants ( n = 20) performed a warm-up exercise to induce light sweating prior to an SAP on chlorpyrifos(cp)-treated nylon carpet. Absorbed daily dosages (ADDs) were calculated using urinary biomonitoring of trichloropyridinol. In two separate exposures, participation in the warm-up exercise prior to the exposure SAP resulted in an increased ADD of CP equivalents by approximately 50%. Measured ADDs averaged 2.8 ( SAP 1) and 2.0 (SAP 2) mug CP equivalents/kg/day in volunteers who participated in the warm-up exercise. In participants who rested prior to the exposures, ADDs were significantly lower at 1.9 (SAP 1) and 1.3 (SAP 2) mug CP equivalents/ kg/day. Perspiration may also be a determinant of exposure in active children and field workers. Measured ADDs were less than estimates of ADD made from environmental measurements including CP deposition, the California roller, and clothing dosimeters worn by participants.
This review gives an overview of focal plane array (FPA)-based infrared (IR) thermography as a powerful research method in the field of physiology and medicine. Comparison of the gained results with the data previously obtained by other authors with other research tools is given. Outer thermoregulatory manifestations displayed by the human organism subjected to whole-body heating (sauna bath) and physical loads (exercise bicycling) are quantitatively analysed. Some details of human body emotional sweating (psychophysiological effect) are reported. Particular attention is paid to studying active sweat glands as individual objects. All experimental data were obtained with the help of a high-sensitivity (0.03 degrees C) fast 128 x 128 InAs IR detector-based thermal imaging system operating in the short-wave spectral region (2.5 to 3 mu m) and perfectly suiting medical purposes. It is shown that IR thermography makes it possible to overcome limitations inherent to contact measuring means that were traditionally used before in thermal studies. It is also shown that heterogeneous thermograms displayed by organisms with disturbed inner equilibrium can be quantitatively analysed in terms of statistical parameters of related surface-temperature histograms, such as the mean temperature and the standard deviation of temperature (SDT). The increase and the decrease in SDT turned out to be typical of prolonged physical load and subsequent relaxation, and of external whole-body heating, respectively. Explanation of this result based on a hypothesis advanced within the context of the doctrine of human-organism evolution is given. Skin-temperature distribution function accompanying the relaxed organism in normality was found to closely resemble normal-distribution function. Symmetry break down and variation of the shape of this characteristic may serve as an indicator of homeostasis shift and can be used as a quantitative criterion for the latter. A new phenomenon, stable punctate hidrosis, is discovered and described. The term sweatology is introduced to refer to the discussed specific research area in biomedical science.
Ethanol intake is associated with a variety of skin diseases. The aim of the present study was (1) to identify the pathways of release of orally administered ethanol through the skin, and (2) to investigate the effects of a single oral dose of ethanol on the penetration of topically applied substances into the skin. Ethanol evaporation via the skin was measured using the new technique of ion mobility spectrometry (IMS). Transepidermal water loss (TEWL) and skin surface temperature were simultaneously measured before and after ethanol consumption. Measurements were performed on skin sites with different stratum corneum (SC) thickness, and density of follicles and sweat glands. These appendages were selectively sealed to investigate their participation in ethanol evaporation. The penetration of a topically applied UV filter substance was studied before and after ethanol consumption after removing the SC with adhesive tape. Ethanol evaporation was measured within 5 min of consumption, while the skin surface temperature remained nearly constant. The sealing of the appendages did not have a significant effect on ethanol evaporation. On the forehead, a higher TEWL value was measured than on the forearm. On both skin sites, an increase in TEWL was observed after ethanol ingestion. No influence of orally administered ethanol on the penetration of the topically applied UV filter substance was observed. The results indicate that ethanol evaporation occurs via the lipid layers without a significant effect on the penetration of the topically applied substance.
We have found that hydrogen gas and acetone vapor emanate from human skin. Emanation gases from human skin were collected for 5-10 min from arm, palm, or forefinger with a homemade probe and bags. The trapped gases were analyzed by gas chromatography, and hydrogen gas and acetone vapor were found to exist in all subjects. The probe (44 mm outer diameter, 6 mm height and inner volume of 3.8 mL) directly covered a 9.4 cm 2 -flat skin surface of the arm, and a modified Tedlar bag or aluminum bag could cover a finger or the whole palm. The average rates of acetone vapor and hydrogen gas released from human skin (15 subjects) is 80-800 and 5-50 pg cm −2 min −1 , respectively. There is a good linear relationship between the emanation rate and the concentration of those gases in human breath. Correlation factors for acetone vapor and hydrogen gas are 0.81 and 0.66, respectively. The proposed non-invasive clinical technique imposes only very minor physical stress on a subject during sampling.
Highlights • A novel, small wireless device for perspiration monitoring was developed. • The developed device consists of a stand-alone humidity sensor and desiccant. • Water vapor from the skin can be detected as perspiration by a humidity sensor. • The amount of perspiration can be calculated by the Fick's laws of diffusion. • Experiments involving human subject proved the validity of developed device.
The specific properties of porous materials when wet, namely the cooling effect near the surface due to the heat extraction during water evaporation, were known and used by ancient civilisations. During human perspiration, the necessary heat for sweat evaporation is provided by the cutaneous surface, which induces a temperature drop similar to that observed in a wet porous material. The potential for using porous materials to simulate human perspiration was investigated in this work using different permanently saturated porous materials (plaster, white clay and red clay). The existence and duration of a constant drying rate was studied, as well its dependency on the surrounding conditions, namely temperature, moisture and velocity. We verified the existence of a period with constant drying rate for all the tested samples; this is evidence that a uniformly distributed humid layer is formed and stays on the external surface of the porous body. This represents a step forward in simulation of the sweating mechanism. All three tested porous materials showed very good reproducibility and good sensitivity in terms of the response of the evaporation rate to any variation of the relative humidity.