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Skin water content monitoring is important for diagnostics and management of edema, dehydration, and other skin conditions as well as for cosmetic applications. Because optoacoustic (OA) technique has high (optical) contrast and (ultrasound) resolution and significant probing depth, it may be suitable for accurate, noninvasive water content monitoring in the skin. In this work we studied OA response from skin tissue phantoms and human wrist skin in the wavelength range from 1370 nm to 1650 nm using a novel, tunable OPO OA system. We identified optimal wavelengths for OA water content monitoring in different skin layers. The results of our study suggest that the OA technique may become a valuable, quantitative tool for accurate, high-resolution water content monitoring in the skin and other tissues and may find wide applications in dermatology, cosmetology, and tissue trauma management. This article is protected by copyright. All rights reserved.

The millimeter-wave band is an ideal part of the electromagnetic radiation to diagnose human skin conditions because this radiation interacts only with tissue down to a depth of a millimetre or less over the band range from 30 GHz to 300 GHz. In this paper, radiometry is used as a non-contact sensor for measuring the human skin reflectance under normal and wet skin conditions. The mean reflectance of the skin of a sample of 50 healthy participants over the (80&ndash, 100) GHz band was found to be ~0.615 with a standard deviation of ~0.088, and an experimental measurement uncertainty of &plusmn, 0.005. The thinner skin regions of the back of the hand, the volar forearms and the inner wrist had reflectances 0.068, 0.068 and 0.062 higher than the thicker skin regions of the palm of the hand, the dorsal forearm and the outer wrist skin. Experimental measurements of human skin reflectance in a normal and a wet state on the back of the hand and the palm of the hand regions indicated that the mean differences in the reflectance before and after the application of water were ~0.078 and ~0.152, respectively. These differences were found to be statistically significant as assessed using t-tests (34 paired t-tests and six independent t-tests were performed to assess the significance level of the mean differences in the reflectance of the skin). Radiometric measurements in this paper show the quantitative variations in the skin reflectance between locations, sexes, and individuals. The study reveals that these variations are related to the skin thickness and water content, a capability that has the potential to allow radiometry to be used as a non-contact sensor to detect and monitor skin conditions such as eczema, psoriasis, malignancy, and burn wounds.

Current thermal sensation estimation models mostly are suitable for the sedentary condition, failing to consider the difference of human thermal sensation in different activity states. This has caused critical limitations in accurately predicting thermal sensation. Moreover, the development method of current models primarily relied on regression analysis, which ignored the non-linear characteristics between the skin temperature and thermal sensation. This paper aimed to identify the significant parameters that can accurately estimate human thermal sensation in different activity states by experimenting and developing the estimation model based on the Takagi–Sugeno (T–S) fuzzy model. A series of human subject experiments were carried out in an environment chamber. The results indicated the feasibility of using wrist skin temperature and its time differential and heart rate as variables for developing thermal sensation estimation model. After that, the T–S fuzzy model was used to develop the thermal sensation estimation models, taking into account the influence of gender. To analyze the applicability of the estimation models in an unstable condition, several experiments were further carried out in the actual built environment. The study revealed that the thermal sensation estimation model based on skin temperature and its time differential and heart rate showed a high degree of accuracy, while the estimation model based only on skin temperature and heart rate also indicated good prediction effect. In addition, the verification results illustrated that the proposed models can predict the human thermal sensation in the unstable environmental condition.

Existing automatic control of building thermal environments do not consider the individual's real-time thermal sensation, which could reduce the occupants’ thermal comfort. Therefore, it is very important to accurately obtain an individual's thermal sensation and real-time reflect on the control logic of air-conditioning systems. Current thermal sensation estimation models mostly apply to sedentary condition without considering human sensation in different activity states, which caused these models have critical limitations in accurately predicting human thermal sensation. In this paper, an intelligent wristband device is used for online monitoring of human thermal characteristics in different active states. The wrist skin temperature and its time differential as well as the heart rate are used for the evaluation index of human thermal sensation, and a series of environmental chamber experiments are carried out to obtain the relationship between the wrist skin temperature and thermal sensation in different activity states in summer. The correlation models of human thermal sensation, wrist skin temperature and its time differential, and heart rate has been formulated by statistical analysis and correlation analysis. In order to verify the feasibility of correlation models in the unstable environmental condition, several tests were conducted in the actual built environment. This study indicates that the wrist skin temperature and its time differential and heart rate can be used for estimating human thermal sensation with a high degree of accuracy in the different activity states. In addition, results of this study also demonstrate the promising applicability of obtained correlation models in the unstable environmental condition.

The authors would like to thank all the participants who took part in this investigation. This study is part of a PhD thesis conducted in the Biomedicine Doctoral Studies of the University of Granada, Spain. We are grateful to Alberto Quesada-Aranda for helping with the development of the Temperatus software (free trial at http://profith.ugr.es/ temperatus?lang=en). We are grateful to Ms Carmen Sainz-Quinn for assistance with English-language editing, Objective: This study aimed to examine whether brown adipose tissue (BAT) or skeletal muscle activity mediates the relationship between personal level of environmental temperature (Personal-ET) and wrist skin temperature (WT). Moreover, we examined whether BAT and skeletal muscle have a mediating role between Personal-ET and WT (as a proxy of peripheral vasoconstriction/vasodilation). Methods: The levels of BAT were quantified by cold-induced 18F-fluorodeoxyglucose–positron emission tomography/computed tomography scan and measured the Personal-ET and WT by using iButtons (Maxim Integrated, Dallas, Texas) in 75 participants (74.6% women). Results: The study found that BAT volume and metabolic activity played a positive and significant role (up to 25.4%) in the association between Personal-ET and WT. In addition, at the coldest temperatures, the participants with lower levels of WT (inducing higher peripheral vasoconstriction) had higher levels of BAT outcomes, whereas in warm temperatures, participants with higher levels of WT (inducing higher peripheral vasodilation) had lower levels of BAT outcomes. The study did not find any mediating role of skeletal muscle activity. Conclusions: BAT volume and metabolic activity play a role in the relationship between Personal-ET and WT. Moreover, the data suggest that there are two distinct phenotypes: individuals who respond better to the cold, both through nonshivering thermogenesis and peripheral vasoconstriction, and individuals who respond better to the heat., This study was supported by the Spanish Ministry of Economy and Competitiveness, Fondo de Investigación Sanitaria del Instituto de Salud Carlos III (PI13/01393), Retos de la Sociedad (DEP2016‐79512‐R), and Fondos Estructurales de la Unión Europea (FEDER); by the Spanish Ministry of Education (FPU 13/04365); by the Fundación Iberoamericana de Nutrición; by the Redes Temáticas de Investigación Cooperativa RETIC (Red SAMID RD16/0022); by AstraZeneca HealthCare Foundation; by the University of Granada, Plan Propio de Investigación 2016, Excellence actions: Units of Excellence; Unit of Excellence on Exercise and Health (UCEES); and by the Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades and European Regional Development Fund (ERDF), ref. SOMM17/6107/UGR, Programa Contratos‐Puente. MAR is supported by a predoctoral research grant from University Jaume I (PREDOC/2015/13). AMN was supported by the Ministry of Economy and Competitiveness, the Instituto de Salud Carlos III through the Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CB16/10/00239), and grant 19899/GERM/15 (cofinanced by FEDER).

In this study, we further investigate whether skin temperature can also assess individual thermal sensation as an effective physiological index while previous studies did not draw broadly generalizable conclusions at high temperature. The climate-controlled experiments include five temperature levels of 26, 30, 33, 37 and 39 °C, two relative humidity levels of 50% and 70%, and two activity levels with light and moderate and in which the estimated average metabolic rate were respectively 58 W/m2 and 165 W/m2. A total of 136 healthy subjects who lived in hot-humid climate for a long time participated in these experiments. During the experiments, the ratings of thermal sensation, comfort and acceptability were documented, local skin temperatures were continuously monitored, and five mean skin temperatures were calculated. Using Fisher discriminant analysis to model thermal sensation from skin temperature, then obtaining the thresholds of local and mean skin temperatures corresponding to different thermal sensation categories, and finally verifying the accuracy of the models assessment. The results show that the skin temperature can also predict thermal sensation at high temperatures of 30–39 °C beyond the range of normal temperatures. The proposed evaluation models show a high accuracy to predict the “hot/very hot” category, and up to 93% accuracy of predicting thermal sensation from wrist skin temperature. Additionally, thermal adaptation to high temperature and humidity can affect the prediction accuracy of “hot/very hot” category from skin temperature. The results of this study provide an important basis for early warning when human's safety risk occurs under high temperatures.

Centralized HVAC systems are usually unable to cater to individual requirements when multiple occupants are present in the same zone. Personalized Comfort Systems (PCS) such as local fans and heaters, heated/cooled chairs, local ventilation systems, have shown to be useful for maintaining comfortable thermal conditions by creating a microclimate around each occupant. Previous studies have mostly focused on personalized thermal comfort modeling under regular HVAC operations, and there is a lack of work that focuses on personalized thermal comfort modeling when PCS devices are in use. In this study, we compare different sensing and machine learning methods to build personal comfort models when a local fan or heater is in use. The experiment was conducted in a controlled environment with three segments: regular (no fan/heater), fan on, and heater on. Our results indicate that the data from environmental sensors results in 2%–5% higher prediction accuracy compared to using a wearable device to monitor wrist skin temperature or thermal imaging to monitor skin temperature from different regions of the face. Furthermore, environmental sensors are more affordable and have relatively fewer privacy concerns compared to the physiological sensors. Overall, the results of this study support the use of environmental sensors for building personalized thermal comfort models with or without PCS. Furthermore, the results also highlight the need for building separate personalized thermal comfort models when PCS devices are in use, and when PCS devices are not in use.

Core and peripheral body temperatures are affected by changes in reproductive hormones during the menstrual cycle. Women worldwide use the basal body temperature (BBT) method to aid and prevent conception. However, prior research suggests that taking one’s daily temperature can prove inconvenient and subject to environmental factors. We investigate whether a more automatic, non-invasive temperature measurement system can detect changes in temperature across the menstrual cycle. We examined how wrist skin temperature (WST), measured with wearable sensors, correlates with urinary tests of ovulation and may serve as a new method of fertility tracking. One hundred and thirty-six eumenorrheic, non-pregnant women participated in an observational study. Participants wore WST biosensors during sleep and reported their daily activities. An at-home luteinizing hormone (LH) test was used to confirm ovulation. WST was recorded across 437 cycles (mean cycles/participant = 3.21, S.D. = 2.25). We tested the relationship between the fertile window and WST temperature shifts, using the BBT three-over-six rule. A sustained 3-day temperature shift was observed in 357/437 cycles (82%), with the lowest cycle temperature occurring in the fertile window 41% of the time. Most temporal shifts (307/357, 86%) occurred on ovulation day (OV) or later. The average early-luteal phase temperature was 0.33°C higher than in the fertile window. Menstrual cycle changes in WST were impervious to lifestyle factors, like having sex, alcohol, or eating prior to bed, that, in prior work, have been shown to obfuscate BBT readings. Although currently costlier than BBT, the present study suggests that WST could be a promising, convenient parameter for future multiparameter fertility awareness methods.

Circadian rhythms are ≈ 24 h oscillations in physiology and behavior, and disruptions have been shown to have negative effects on health. Wrist skin temperature has been used by several groups as a valid method of assessing circadian rhythms in humans. We tested the hypothesis that circadian temperature amplitude (TempAmp) and stability (TempStab) would significantly differ among groups of healthy young men of varying adiposities, and that we could identify physiological and behavioral measures that were significantly associated with these temperature parameters. Wrist skin temperatures taken at 10 min intervals for 7 consecutive days were determined in 18 optimal (OGroup), 20 fair (FGroup) and 21 poor (PGroup) %Fat grouped young men and subsequently analyzed using available validated software. Body composition, cardiorespiratory fitness, actigraphy, daily nutritional and sleep data, and fasting lipid, insulin and glucose concentration measures were also determined. Significant changes in TempAmp and TempStab parameters in subjects with a single metabolic syndrome (MetS) risk factor compared to those with no MetS factors was observed. In addition, stepwise multivariate regression analyses showed that 50% of the variance in TempAmp was explained by actigraphy (mean steps taken per day; MSTPD), cardiorespiratory fitness, and late night eating per week (#LNE); and 57% in TempStab by MSTPD, time spent in moderate-to-vigorous activity per day, fat mass, and #LNE. Overwhelmingly, physical activity was the most important measure associated with the differences in circadian rhythm parameters. Further research is warranted to determine the effects of increasing the amount and timing of physical activity on the status of the circadian system in a variety of populations.

Background: Surgical gloves are a necessity in performing abdominal and pelvic surgery not only to protect the patient from bacterial contamination but also to protect the surgeon, the nurses and surgical assistants from biological fluids. The interface of the surgical gown and the surgical gloves at the wrist is a site for interruption of the barrier between biological fluids in the open abdomen and the surgeon. Methods: In the under/over method (UOM) for double-glove application the first pair of gloves are positioned under the surgical gown and the second pair are positioned over the cuff of the surgical gown and secured with selfadherent wrap. Results: Using the UOM, the proximal portion of the surgical gloves did not roll down to the wrist. The selfadherent wrap reduced the entrance of biological fluids into the space between the surgical gloves and the cuff of the surgical gown. If the cuff of the surgical gown became wet, it was not in contact with the wrist skin. Conclusion: The UOM prevents the surgical gloves from rolling down on the forearm. Contact of the cuff of the surgical gown with the wrist skin is prevented. The possibility of exposure of the wrist skin to biological fluids, especially large volume irrigation, during abdominal and pelvic surgery may be reduced.

Chronobiology is the scientific discipline that deals with the study of the biological rhythms and their underlying mechanisms. The alteration of biological rhythms, such as blood pressure or temperature begins to be considered as a good marker of certain diseases and senescence. Among the variables, the wrist skin temperature has proven to be a good marker of the circadian rhythms of the subject. In this paper we evaluate the wrist temperature of four groups of subjects with different age in order to gain some knowledge on the evolution of the circadian rhythms and its application to age classification.

A limited-coherence interferometer system for examination of biological materials has been developed. The microrelief profile of human skin was probed in vivo. It was found that the limited-coherence interferometer system can be used as an optical tomograph. Oil penetration into wrist skin subsurface layer was measured using this system.

Date Presented 4/8/2016 This study provides a neurobiological basis for using low-level wrist vibration in upper-extremity sensorimotor rehabilitation and suggests that vibration may complement occupational therapy by providing patients with enhanced sensory experience during therapy for better sensorimotor outcomes. Primary Author and Speaker: Michelle L. Woodbury Contributing Authors: Kishor Lakshminarayanan, Abigail W. Lauer, Leonardo Bonilha, Brian D. Schmit

Thermal comfort is an essential environmental factor related to quality of life and work effectiveness. We assessed the feasibility of wrist skin temperature monitoring for estimating subjective thermal sensation. We invented a wrist band that simultaneously monitors skin temperatures from the wrist (i.e., the radial artery and ulnar artery regions, and upper wrist) and the fingertip. Skin temperatures from eight healthy subjects were acquired while thermal sensation varied. To develop a thermal sensation estimation model, the mean skin temperature, temperature gradient, time differential of the temperatures, and average power of frequency band were calculated. A thermal sensation estimation model using temperatures of the fingertip and wrist showed the highest accuracy (mean root mean square error [RMSE]: 1.26 ± 0.31). An estimation model based on the three wrist skin temperatures showed a slightly better result to the model that used a single fingertip skin temperature (mean RMSE: 1.39 ± 0.18). When a personalized thermal sensation estimation model based on three wrist skin temperatures was used, the mean RMSE was 1.06 ± 0.29, and the correlation coefficient was 0.89. Thermal sensation estimation technology based on wrist skin temperatures, and combined with wearable devices may facilitate intelligent control of one’s thermal environment.

Background Objective measurements of skin blood flow would have predictive value in assessing the potential for wound healing. In this study, we evaluated the relationship between transcutaneous PO 2 (tcPO 2 ) measurements and hyperspectral reflectance spectroscopy measurements of oxygenated hemoglobin (OxyHgb), deoxygenated hemoglobin (DeOxyHgb), total hemoglobin (Sum = OxyHgb + DeOxyHgb), and hemoglobin saturation (Sat = 100 × OxyHgb/Sum). The effect of varying tcPO 2 probe temperatures (37 °C, 41 °C, and 45 °C) was also assessed. Methods A Hypermed Oxy-Vu system was used for hyperspectral imaging, with measurements performed 2 minutes after removing tcPO 2 probes (Radiometer). Twenty-three sections of foot or wrist skin in four healthy volunteers were measured at 37 °C, 41 °C, and 45 °C using both modalities. Results TcPO 2 at 37 °C was 23.1 ± 24.8 mm Hg, increasing to 63.0 ± 27.3 mm Hg at 45 °C. OxyHgb levels increased from 52.4 ± 25.4 at 37 °C to 101.3 ± 23.8 at 45 °C. Linear regression analysis of the HSI data at 37 °C showed a positive correlation between tcPO 2 and OxyHgb ( r 2 = 0.35, P = 0.003), tcPO 2 and DeOxyHgb ( r 2 = 0.63, P 2 and Sum ( r 2 = 0.60, P r 2 = 0.001, P = 0.92). As the probe temperature increased, the correlations of tcPO 2 with OxyHgb, DeoxyHgb, and Sum became progressively much weaker. Conclusion A marked increase in the HSI measurements of OxyHgb in skin exposed to heated tcPO 2 probes was observed, with tcPO 2 , Sat, and Sum measurements also observed to increase with temperature. These measurements were influenced by heat inducing vasodilatation in the superficial skin layers. HSI measurements may be clinically useful for measuring wound healing potential, as they correlate with tcPO 2 levels under normal physiological conditions.

In this work, we have characterized the permittivity of human epidermis (outer skin layer) using microwave up to 110 GHz. A one mm-diameter coaxial probe was adopted to increase measuring bandwidth as well as to enhance the spatial resolution. Pork was used to discriminate the permittivities between muscle tissues and fat tissues. The influence of the sample thickness was also. studied. Considering several factors, the permittivity was measured on epidermis of the human palm and the wrist. In addition, a relaxation phenomenon observed in the wrist skin, revealed by Cole-Cole parameters, suggested that it originated from high water content beneath the thin epidermis of the wrist skin. A relaxation phenomenon revealed by Cole-Cole parameters was observed in the wrist skin. This explains that high water content cells exist beneath the thin epidermis of the wrist skin.

A review of 429 cases of carpal tunnel syndrome in 329 patients confirms the prevalence of this entity among disorders of the hand. Three symptoms are almost diagnostic--daytime numbness, nighttime pain, and morning stiffness of the fingers. The diagnosis is confirmed by findings on physical examination. A relatively simple technique is presented for the exposure and release of the median nerve, using a longitudinal incision in the palm and stopping short of the wrist skin. Limiting the incision to the palmar skin results in an inconspicuous scar, while still providing adequate exposure for a complete anatomical release. An epineural neurolysis of the median nerve was performed in each case, resulting in improvement in the symptoms in all but 4 of these 429 patients.