A crosstalk-free dual-mode sweat sensing system for naked-eye sweat loss quantification via changes in structural reflectance

Sweat loss monitoring is important for understanding the body’s thermoregulation and hydration status,as well as for comprehensive sweat analysis.Despite recent advances,developing a low-cost,scalable,and universal method for the fabrication of colorimetric microfluidics designed for sweat loss monitoring remains challenging.In this study,we propose a novel laserengraved surface roughening strategy for various flexible substrates.This process permits the construction of microchannels that show distinct structural reflectance changes before and after sweat filling.By leveraging these unique optical properties,we have developed a fully laser-engraved microfluidic device for the quantification of naked-eye sweat loss.This sweat loss sensor is capable of a volume resolution of 0.5µL and a total volume capacity of 11µL,and can be customized to meet different performance requirements.Moreover,we report the development of a crosstalk-free dual-mode sweat microfluidic system that integrates an Ag/AgCl chloride sensor and a matching wireless measurement flexible printed circuit board.This integrated system enables the real-time monitoring of colorimetric sweat loss signals and potential ion concentration signals without crosstalk.Finally,we demonstrate the potential practical use of this microfluidic sweat loss sensor and its integrated system for sports medicine via on-body studies.

In situ forming injectable MSC-loaded GelMA hydrogels combined with PD for vascularized sweat gland regeneration

Dear Editor,Three dimensional(3D)bioprinted extracellular matrix(ECM)can be used to provide both biochemical and biophysical cues to direct mesenchymal stem cells(MSCs)differentiation,and then differentiated cells were isolated for implantation in vivo using surgical procedures.However,the reduced cell activity after cell isolation from 3D constructs and low cell retention in injured sites limit its application[1].Methacrylated gelatin(GelMA)hydrogel has the advantage of fast crosslinking,which could resemble complex architectures of tissue construct in vivo[2].Here,we adopted a noninvasive bioprinting procedure to imitate the regenerative microenvironment that could simultaneously direct the sweat gland(SG)and vascular differentiation from MSCs and ultimately promote the replacement of glandular tissue in situ(Fig.1a).

Wearable sweat biosensors on textiles for health monitoring

With the rapid technological innovation in materials engineering and device integration,a wide variety of textilebased wearable biosensors have emerged as promising platforms for personalized healthcare,exercise monitoring,and pre-diagnostics.This paper reviews the recent progress in sweat biosensors and sensing systems integrated into textiles for wearable body status monitoring.The mechanisms of biosensors that are commonly adopted for biomarkers analysis are first introduced.The classification,fabrication methods,and applications of textile conductors in different configurations and dimensions are then summarized.Afterward,innovative strategies to achieve efficient sweat collection with textile-based sensing patches are presented,followed by an in-depth discussion on nanoengineering and system integration approaches for the enhancement of sensing performance.Finally,the challenges of textile-based sweat sensing devices associated with the device reusability,washability,stability,and fabrication reproducibility are discussed from the perspective of their practical applications in wearable healthcare.

Review:Wearable Sweat Sensors for Diseases Prevention and Monitoring

Advanced in wireless technologies and flexible materials with great biocompatibility,wearable devices have been utilized in the field of healthcare,sports management,and diseases prevention,which have been widely applied in current electronic equipment.Sweat,as a common metabolite on the skin surface,contains a wealth of biomarkers for disease detection and diagnosis.Therefore,developing wearable sweat sensors can provide a non⁃invasive method for health data collecting,sports monitoring,and clinical diagnosis in a convenient way.Recent research in sweat metabolomics has offered a lot of information for sweat analysis and the wearable sweat sensors with small size,various sensing,and transmission units,and good skin contact has exhibited dynamic multi⁃signal detection.This article introduces the biomarkers in sweat related to different diseases and the current development of sweat sensors for user􀆳s activation monitoring and diseases detection.The barriers and difficulties in the future are also discussed and perspectives in the next generation sweat sensors are proposed.

Corrosion behavior of brass coinage in synthetic sweat solution

Corrosion behavior of brass coinage was investigated in synthetic sweat solution by electrochemical measurement and surface analysis methods including scanning electron microscope （SEM） and energy dispersive X-ray spectrometer （EDX）. It is indicated that chloride ions in sweat solution accelerate the anodic active dissolution of brass, which is the main reason of pitting corrosion and dezincification corrosion. Meanwhile, lactic acid and ammonia water also promote the anode reaction. The corrosion products on the surface are mainly composed of basic copper chloride, cuprous oxide, the complex consisting of urea in association with copper, and few lactate ion. The kinetics of pitting corrosion development obeys the following equation of J0=0.3735（t＋185.93）^-1/2, and the process is controlled by dissolution of salt deposited on pit surface.

Porocarcinoma in a palm reconstructed with a full thickness skin graft: A case report

BACKGROUND Porocarcinoma is a rare type of skin cancer that originates from sweat gland tumors.It is an aggressive malignant skin cancer that is difficult to diagnose clinically owing to its rarity and similarity to squamous cell carcinoma(SCC).CASE SUMMARY This case involved a 92-year-old woman,a farmer by profession,presented with an exophytic and verrucous mass on her left palm that had formed 2 years prior and caused chronic pain and frequent bleeding.Initially,the patient was diagnosed with SCC using a punch biopsy;however,a repeat biopsy with addi-tional immunohistochemical tests was performed for porocarcinoma.Ultimately,the patient was diagnosed with porocarcinoma and reconstruction was planned using a full-thickness skin graft.After treatment,the range of motion of the palm was preserved,and the aesthetic outcome was favorable.At 6 mo of follow-up,the patient was satisfied with the outcome.CONCLUSION Porocarcinoma is commonly misdiagnosed as SCC;therefore,clinicians should consider porocarcinomas when evaluating mass-like lesions on the hands.

Eccrine porocarcinoma in the tempus of an elderly woman:A case report

BACKGROUND Eccrine porocarcinoma(EPC)is a rare skin tumor that mainly affects the elderly population.Tumors often present with slow growth and a good prognosis.EPCs are usually distinguished from other skin tumors using histopathology and immunohistochemistry.However,surgical management alone may be inadequate if the tumor has metastasized.However,currently,surgical resection is the most commonly used treatment modality.CASE SUMMARY A seventy-four-year-old woman presented with a slow-growing nodule in her left temporal area,with no obvious itching or pain,for more than four months.Histopathological examination showed small columnar and short spindle-shaped cells;thus,basal cell carcinoma was suspected.However,immunohistochemical analysis revealed the expression of cytokeratin 5/6,p63 protein,p16 protein,and Ki-67 antigen(40%),and EPC was taken into consideration.The skin biopsy was repeated,and hematoxylin and eosin staining revealed ductal differentiation in some cells.Finally,the patient was diagnosed with EPC,and Mohs micrographic surgery was performed.We adapted follow-up visits in a year and not found any recurrence of nodules.CONCLUSION This case report emphasizes the diagnosis and differentiation of EPC.

Emerging wearable flexible sensors for sweat analysis

Sweat,as a biofluid with the potential for noninvasive collection,provides profound insights into human health conditions,because it contains various chemicals and information to be utilized for the monitoring of well-being,stress levels,exercise,and nutrition.Recently,wearable sweat sensors have been developed as a promising substitute to conventional laboratory sweat detection methods.Such sensors are promising to realize low-cost,real-time,in situ sweat measurements,and provide great opportunities for health status evaluation analysis based on personalized big data.This review first presents an overview of wearable sweat sensors from the perspective of basic components,including materials and structures for specific sensing applications and modalities.Current strategies and specific methods of the fabrication of wearable power management are also summarized.Finally,current challenges and future directions of wearable sweat sensors are discussed.

Wearable Sweat Sensors

Sweat, like blood, contains electrolytes and biomolecules that can reveal aspects of a person’s physiology, from hydration to kidney function. Though scientists have long recognized sweat’s potential use as a medical diagnostic tool, only recently have engineering advances allowed them to explore the possibility in earnest.

Small molecules facilitate single factor-mediated sweat gland cell reprogramming

Background: Large skin defects severely disrupt the overall skin structure and can irreversibly damage sweat glands(SGs), thus impairing the skin’s physiological function. This study aims to develop a stepwise reprogramming strategy to convert fibroblasts into SG lineages, which may provide a promising method to obtain desirable cell types for the functional repair and regeneration of damaged skin.Methods: The expression of the SG markers cytokeratin 5(CK5), cytokeratin 10(CK10), cytokeratin 18(CK18), carcinoembryonic antigen(CEA), aquaporin 5(AQP5) and α-smooth muscle actin(α-SMA) was assessed with quantitative PCR(qPCR), immunofluorescence and flow cytometry. Calcium activity analysis was conducted to test the function of induced SG-like cells(iSGCs). Mouse xenograft models were also used to evaluate the in vivo regeneration of iSGCs.BALB/c nude mice were randomly divided into normal group, SGM treatment group and iSGC transplantation group.Immunocytochemical analyses and starch-iodine sweat tests were used to confirm the in vivo regeneration of iSGCs.Results: Ectodermal dysplasia antigen(EDA) overexpression drove human dermal fibroblast(HDF) conversion into i SGCs in SG culture medium(SGM). qPCR indicated significantly increased mRNA levels of the SG markers CK5, CK18and CEA in iSGCs, and flow cytometry data demonstrated(4.18±0.04)% of iSGCs were CK5 positive and(4.36±0.25)%of iSGCs were CK18 positive. The addition of chemical cocktails greatly accelerated the SG fate program. qPCR results revealed significantly increased mRNA expression of CK5, CK18 and CEA in iSGCs, as well as activation of the duct marker CK10 and luminal functional marker AQP5. Flow cytometry indicated, after the treatment of chemical cocktails,(23.05±2.49)% of iSGCs expressed CK5^(+) and(55.79±3.18)% of iSGCs expressed CK18^(+), respectively. Calcium activity analysis indicated that the reactivity of iSGCs to acetylcholine was close to that of primary SG cells [(60.79±7.71)% vs.(70.59±0.34)%, ns]. In vivo transplantation experiments showed approximately(5.2±1.1)% of the mice were sweat test positive, and the histological analysis results indicated that regenerated SG structures were present in iSGCs-treated mice.Conclusions: We developed a SG reprogramming strategy to generate functional iSGCs from HDFs by using the single factor EDA in combination with SGM and small molecules. The generation of iSGCs has important implications for future in situ skin regeneration with SG restoration.

Epidermal self-powered sweat sensors for glucose and lactate monitoring

Sweat could be a carrier of informative biomarkers for health status identification;therefore,wearable sweat sensors have attracted significant attention for research.An external power source is an important component of wearable sensors,however,the current power supplies,i.e.,batteries,limit further shrinking down the size of these devices and thus limit their application areas and scenarios.Herein,we report a stretchable self-powered biosensor with epidermal electronic format that enables the in situ detec-tion of lactate and glucose concentration in sweat.Enzymatic biofuel cells serve as self-powered sensing modules allowing the sweat sensor to exhibit a determination coefficient(R2)of 0.98 with a sensitivity of 2.48 mV/mM for lactate detection,and R2 of 0.96 with a sensitivity of 0.11 mV/μM for glucose detection.The microfluidic channels developed in an ultra-thin soft flexible polydimethylsiloxane layer not only enable the effective collection of sweat,but also provide excellent mechanical properties with stable performance output even under 30%stretching.The presented soft sweat sensors can be integrated at nearly any location of the body for the continuous monitoring of lactate and glucose changes during normal daily activities such as exercise.Our results provide a promising approach to develop next-generation sweat sensors for real-time and in situ sweat analysis.

Sweat detection theory and fluid driven methods: A review

In recent years, analyses of sweat have become more popular since it doesn't require invasive sampling procedures. Although blood still remains the golden standards in clinical, analyses of other common body fluids,such as sweat, have become increasingly important. Because the compositions of sweat and blood are osmotically related, the content of certain metabolites in sweat can directly reflect the disease. Sweat detection can be used as an alternative to blood detection and allows continuous monitoring. Increased development of wearable sensors makes it possible for continuous sweat detection. Here, this paper gave a review about the sweat detection methods, such as fluorescence sensing, electrochemical sensing and colorimetric sensing. The advantages and disadvantages of each method and their developing trend in sweat detection were summarized. Then, for the problem of continuous sweat sampling, three methods(capillary force, hydrogel osmotic pump, evaporationdriven micropump) were introduced through different structures of microfluidic chip, and the level of sweat collection and transport achieved by related research was demonstrated. This review aims to provide guidance for future research in sweat detection and stimulate further interest in continuous monitoring of sweat using microfluidic chip.

Metastatic apocrine sweat gland adenocarcinoma in a terrier dog

This report describes the clinical and pathological aspects of an apocrine sweat gland carcinoma with distant metastasis in an aged dog.A 7-year-old male terrier dog was referred to small animal hospital of Shuhid Bahonar University of Kerman with a 5.5×3.5 centimeter pedunculated mass on its head near left auricular region which had been progressively growing since tliree months ago.The radiography showed no local and distant metastasis.Surgical excision and histological evaluation was done.Histologically,the mass was composed of epithelial cells arranged in glandular and solid patterns.The morphologic findings suggested either a primary or metastatic apocrine-gland carcinoma.Immunohistochemically,the tumor cells were intensely positive for cytokeratin 7 and 20 and negative for S100 protein.On the basis of histopathological and clinical findings,the tumor was diagnosed as a malignant apocrine gland tumor,arising from apocrine sweat glands of the skin.Local tumor recurrence with anorexia and weight loss was reported by the owner nine month later.Severe submandibular and prescapular lymphadenomegaly was noted in clinical examination.Several large pulmonary nodules were noted in chest radiographs resembling mediastinal lymph node metastasis.Second surgery and chemotherapy was rejected by the owner due to grave prognosis of the patient.The animal was died 45 days later due to respiratory complications.Tumors of apocrine sweat glands are relatively uncommon in dogs whereas apocrine gland adenocarcinoma with distant metastasis is extremely rare.

Comparison of the Levels of Five Heavy Metals in Human Urine and Sweat after Strenuous Exercise by ICP-MS

Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the levels of trace heavy metals in human urine and sweat, to compare the performance of ICP-MS using three sample processing methods, namely direct dilution, wet digestion, and microwave digestion. The results showed that the wet digestion ICP-MS method has the highest accuracy (relative standard deviation ≤10%) and is more useful for measuring the levels of trace heavy metals in urine and sweat. Hence, we used this method to compare the levels of the five trace heavy metals, namely chromium, copper, zinc, cadmium, and lead, in the urine and sweat of adults after strenuous exercise. The results showed that the levels of these five trace heavy metals in sweat were significantly higher than those in urine after strenuous exercise (The differences between the measurements in urine and those in sweat were significant P ≤ 0.01). The results suggested that exercise-induced sweating can effectively remove the harmful heavy metals from the human body.

Improved sweat gland function during active heating in tennis athletes

Background：Relatively few studies on the peripheral sweating mechanisms of trained tennis athletes have been conducted.The purpose of this study was to compare the sweating capacities of tennis athletes against untrained subjects（controls）.Methods：Thirty-fi e healthy male volunteers participated including 15 untrained subjects and 20 trained tennis athletes（nationally ranked）.Active heat generation was performed for 30 min（running at 60%VO2max） in a climate chamber（temperature,25.0°C ± 0.5°C;relative humidity,60% ± 3%,termed active heating）.Sweating data（local sweat onset time,local sweat volume,activated sweat glands,sweat output per gland,whole body sweat loss volume） were measured by the capacitance hygrometer-ventilated capsule method and starch-iodide paper.Mean body temperature was calculated from tympanic and skin temperatures.Results：Local sweat onset time was shorter for tennis athletes（p〈0.001）.Local sweat volume,activated sweat glands of the torso and limbs,sweat output per gland,and whole body sweat loss volume were significant y higher for tennis athletes than control subjects after active heating（p〈0.001）.Tympanic and mean body temperatures were lower among tennis athletes than controls（p〈0.05）.Conclusion：These results indicate that tennis athletes had increased regulatory capacity of their sweat gland function.

A preliminary study of loss of nutrients in whole bodysweat in antichemical troops during work in heat

This paper reports the loss of several major nutrients in the sweat from humanbody during working in hot environment,so as to put forward a rational scheme for sup-plying beverages and foods with appropriate nutrients.Thirteen young male subjectsdressed in gas protection equipment of the whole body were ordered to march in a hotclimatic chamber（DB 34.2℃）at a speed of 5.4 km/h until they subjectively failed to bearfurther but to hold on still for 200 m.The results showed that their maximum tolerancetime was only 58.2±2.9 min,the mean body temperature（MBT）was 37.8±0.1 ℃,heartrate（HR）151.3±8.0 beat/min.Nevertheless,the amount of sweat was only 780.5±75.2 g.Thelevels of K,Na,Ca,Mg,Fe,Cu and Zn in the whole body-sweat of our series were12.3±1.8,113.0±7.0,0.8±0.13,0.9±0.20,0.027±0.004,0.005±0.001 and 0.035±0.002mmol/L,respectively.The concentrations of K and Zn in serum were decreased,and thelevel of Zn was also lower than the normal.The total amount of amino acids in thesweat was 10855±679 μmol/L,of which the amount of essential amino acids was 21.2%.The concentration of lysine was the highest（1038.5±90.7μmol/L）,and that of methioninethe lowest（49.8±4.0μmol/L）in the essential amino acids.In the non-essential aminoacids,the concentrations of serine and glycine were the highest,being 2774.3±179.0 and1572.1±83.9 μmol/L,respectively,and that of cystine the lowest,being 4.8±0.9μmol/L.The amount of vitamins B1,B2 and C in the sweat were only 452±220,312±174 and3330±1200 μg/L,respectively.

Detection of HBsAg and HBV DNA in sweat of HBsAg carriers

HBsAg and HBV DNA in the sweat of HBsAg carriers were detected.Thepositivity rates were 26.1%(12/46)by RIA and 17.4%(8/45)by dot blot hybridization.No HBsAg and HBV DNA were found in 6 persons with negative serum HBsAg.Viralparticles were observed in the sweat by means of immunoelectronic microscope.When se-rum HBeAg or HBV DNA were positive,the positivity rates of HBsAg and HBV DNAin sweat were higher than those with negative serum HBeAg and HBV DNA,and the dif-ference was significant.The results suggested that HBV may be excreted out ofbody through the sweat glands of serum HBsAg carriers,and contaminate environmentalobjects,which may play a role in contact transmission of hepatitis B.No relationshipswere found between anti-HBc,anti-HBe,titer of serum HBsAg and positivity rates ofHBsAg and HBV DNA in sweat.

Malignant sweat gland tumor of breast arising in pre-existing benign tumor: A case report

BACKGROUND Sweat glands belong to skin appendages.Sweat gland tumors are uncommon,especially when they occur as malignant tumors in the breast.We report a case of malignant sweat gland tumor of the breast,including imaging and pathological findings.CASE SUMMARY A 47-year-old woman visited our hospital with a non-tender palpable lesion in her left breast.The lesion had not shown changes for 10 years.However,it recently increased in size.Sonography showed a well circumscribed cystic lesion with internal debris and fluid-fluid level.Magnetic resonance imaging showed a well circumscribed oval mass with T1 hyper-intensity compared to muscle and T2 high signal intensity.There was a small enhancing mural component in the inner wall of the mass.The tumor was resected.Its pathologic result was a malignant transformation of benign sweat gland tumor such as hidradenoma.The lesion was treated with excision and radiation therapy.At 1-year follow up,there was no local recurrence or metastasis in the patient.CONCLUSION In the case of a rapid growing cystic mass in the nipple and subareola,it is necessary to distinguish it from a malignant sweat gland tumor.

Gray Synthetic Evaluation on Moisture Comfort of Sportswear Fabrics under the Condition of Heavy Sweating

Moisture and water transfer under the condition of heavy sweating are analyzed. Four different experiments are made to test moisture resistance, water-keep, wicking effect and drying ability of samples. Then gray analysis method is introduced to evaluate the comprehensive comfort of these fabrics. Result shows chemical fiber with high moisture transfer performance has advantage in water transfer and diffusion, which is suitable for human under the condition of heavy sweating. Though natural fiber can absorb moisture well, it cannot transfer fluid sweat. Therefore natural fiber fabrics such as cotton, wool are unsuitable to make functional sportswear.

Development of a New-type Sweating Manikin System

A new type of sweating manikin system has been developed to evaluate thermal insulation and moisture evaporative resistance of clothing, which is reliable, easy control and low cost. In this paper the manikin system was reported and discussed from the aspects of system construction, work principles, figure formation, simulated sweating system, and technical properties.