Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

An on-skin platform for wireless monitoring of flow rate, cumulative loss and temperature of sweat in real time

Abstract

Monitoring the flow rate, cumulative loss and temperature of sweat can provide valuable physiological insights for the diagnosis of thermoregulatory disorders and illnesses related to heat stress. However, obtaining accurate, continuous estimates of these parameters with high temporal resolution remains challenging. Here, we report a platform that can wirelessly measure sweat rate, sweat loss and skin temperature in real time. The approach combines a short, straight fluid passage to capture sweat as it emerges from the skin with a flow sensor that is based on a thermal actuator and precision thermistors, and that is physically isolated from, but thermally coupled to, the sweat. The platform transfers data autonomously using a Bluetooth Low Energy system on a chip. Our approach can also be integrated with advanced microfluidic systems and colorimetric chemical reagents for the measurement of pH and the concentration of chloride, creatinine and glucose in sweat.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Design features and operating principles of a miniaturized, flexible module for remote, on-skin sensing of sweat rate.
Fig. 2: Experimental studies and FEA of key characteristics of the thermal flow sensor.
Fig. 3: A skin-interfaced, wireless system for continuous monitoring of sweat rate, sweat loss and temperature.
Fig. 4: On-body measurements of sweat flow rate and total loss for physical activity and dehydration monitoring.
Fig. 5: Multimodal sensing of sweat rate and loss, skin temperature and various sweat biomarkers.

Data availability

Supporting data are available from the corresponding author upon reasonable request. Source data are provided with this paper.

Code availability

Custom-developed firmware for BLE SoCs and Android applications (user interfaces) for use on smartphones are available from the corresponding author upon reasonable request. All requests for source code will be reviewed by the corresponding author to verify whether the request is subject to any intellectual property or confidentiality obligations.

References

  1. 1.

    Baker, L. B. Sweating rate and sweat sodium concentration in athletes: a review of methodology and intra/interindividual variability. Sports Med. 47, 111–128 (2017).

    Google Scholar 

  2. 2.

    Gambhir, S. S., Ge, T. J., Vermesh, O. & Spitler, R. Toward achieving precision health. Sci. Transl. Med. 10, eaao3612 (2018).

    Google Scholar 

  3. 3.

    Bariya, M., Nyein, H. Y. Y. & Javey, A. Wearable sweat sensors. Nat. Electron. 1, 160–171 (2018).

    Google Scholar 

  4. 4.

    Sonner, Z. et al. The microfluidics of the eccrine sweat gland, including biomarker partitioning, transport and biosensing implications. Biomicrofluidics 9, 031301 (2015).

    Google Scholar 

  5. 5.

    Gao, W. et al. Fully integrated wearable sensor arrays for multiplexed in situ perspiration analysis. Nature 529, 509–514 (2016).

    Google Scholar 

  6. 6.

    Reeder, J. T. et al. Waterproof, electronics-enabled, epidermal microfluidic devices for sweat collection, biomarker analysis and thermography in aquatic settings. Sci. Adv. 5, eaau6356 (2019).

    Google Scholar 

  7. 7.

    Bandodkar, A. J. et al. Battery-free, skin-interfaced microfluidic/electronic systems for simultaneous electrochemical, colorimetric and volumetric analysis of sweat. Sci. Adv. 5, eaav3294 (2019).

    Google Scholar 

  8. 8.

    Baker, L. B., Stofan, J. R., Hamilton, A. A. & Horswill, C. A. Comparison of regional patch collection vs. whole body washdown for measuring sweat sodium and potassium loss during exercise. J. Appl. Physiol. 107, 887–895 (2009).

    Google Scholar 

  9. 9.

    Maughan, R. J. et al. Water balance and salt losses in competitive football. Int. J. Sport Nutr. Exerc. Metab. 17, 583–594 (2007).

    Google Scholar 

  10. 10.

    Williams, C. A. & Blackwell, J. Hydration status, fluid intake and electrolyte losses in youth soccer players. Int. J. Sports Physiol. Perform. 7, 367–374 (2012).

    Google Scholar 

  11. 11.

    Al-omari, M. et al. A portable optical human sweat sensor. J. Appl. Phys. 116, 183102 (2014).

    Google Scholar 

  12. 12.

    Bandodkar, A. J. & Wang, J. Non-invasive wearable electrochemical sensors: a review. Trends Biotechnol. 32, 363–371 (2014).

    Google Scholar 

  13. 13.

    Dam, V. A. T., Zevenbergen, M. A. G. & van Schaijk, R. Toward wearable patch for sweat analysis. Sens. Actuators B Chem. 236, 834–838 (2016).

    Google Scholar 

  14. 14.

    Bain, A. R., Deren, T. M. & Jay, O. Describing individual variation in local sweating during exercise in a temperate environment. Eur. J. Appl. Physiol. 111, 1599–1607 (2011).

    Google Scholar 

  15. 15.

    Patterson, M. J., Galloway, S. D. R. & Nimmo, M. A. Variations in regional sweat composition in normal human males. Exp. Physiol. 85, 869–875 (2000).

    Google Scholar 

  16. 16.

    Matzeu, G., Fay, C., Vaillant, A., Coyle, S. & Diamond, D. A wearable device for monitoring sweat rates via image analysis. IEEE Trans. Biomed. Eng. 63, 1672–1680 (2016).

    Google Scholar 

  17. 17.

    Choi, J., Ghaffari, R., Baker, L. B. & Rogers, J. A. Skin-interfaced systems for sweat collection and analytics. Sci. Adv. 4, eaar3921 (2018).

    Google Scholar 

  18. 18.

    Francis, J., Stamper, I., Heikenfeld, J. & Gomez, E. F. Digital nanoliter to milliliter flow rate sensor with in vivo demonstration for continuous sweat rate measurement. Lab Chip 19, 178–185 (2019).

    Google Scholar 

  19. 19.

    Iftekhar, A. T., Ho, J. C.-T., Mellinger, A. & Kaya, T. 3D modeling and characterization of a calorimetric flow rate sensor for sweat rate sensing applications. J. Appl. Phys. 121, 094505 (2017).

    Google Scholar 

  20. 20.

    Brueck, A., Iftekhar, T., Stannard, B. A., Yelamarthi, K. & Kaya, T. A real-time wireless sweat rate measurement system for physical activity monitoring. Sensors 18, 533 (2018).

    Google Scholar 

  21. 21.

    Farrell, P. M. et al. Guidelines for diagnosis of cystic fibrosis in newborns through older adults: Cystic Fibrosis Foundation consensus report. J. Pediatr. 153, S4–S14 (2008).

    Google Scholar 

  22. 22.

    Moyer, J., Wilson, D., Finkelshtein, I., Wong, B. & Potts, R. Correlation between sweat glucose and blood glucose in subjects with diabetes. Diabetes Technol. Ther. 14, 398–402 (2012).

    Google Scholar 

  23. 23.

    Robinson, S. & Robinson, A. H. Chemical composition of sweat. Physiol. Rev. 34, 202–220 (1954).

    Google Scholar 

  24. 24.

    Bass, D. E. & Dobalian, I. T. Ratio between true and apparent creatinine in sweat. J. Appl. Physiol. 5, 555–558 (1953).

    Google Scholar 

  25. 25.

    Al-Tamer, Y. Y., Hadi, E. A. & Al-Badrani, I. E. I. Sweat urea, uric acid and creatinine concentrations in uraemic patients. Urol. Res. 25, 337–340 (1997).

    Google Scholar 

  26. 26.

    Harvey, C. J., LeBouf, R. F. & Stefaniak, A. B. Formulation and stability of a novel artificial human sweat under conditions of storage and use. Toxicol. In Vitro 24, 1790–1796 (2010).

    Google Scholar 

  27. 27.

    Huang, C.-T., Chen, M.-L., Huang, L.-L. & Mao, I.-F. Uric acid and urea in human sweat. Chin. J. Physiol. 45, 109–115 (2002).

    Google Scholar 

  28. 28.

    Brinkman, J. E. & Sharma, S. Physiology, Metabolic Alkalosis (StatPearls Publishing, 2019).

    Google Scholar 

  29. 29.

    Patterson, M. J., Galloway, S. D. R. & Nimmo, M. A. Effect of induced metabolic alkalosis on sweat composition in men. Acta Physiol. Scand. 174, 41–46 (2002).

    Google Scholar 

  30. 30.

    Choi, J. et al. Soft, skin-integrated multifunctional microfluidic systems for accurate colorimetric analysis of sweat biomarkers and temperature. ACS Sens. 4, 379–388 (2019).

    Google Scholar 

  31. 31.

    Zhang, Y. et al. Passive sweat collection and colorimetric analysis of biomarkers relevant to kidney disorders using a soft microfluidic system. Lab Chip 19, 1545–1555 (2019).

    Google Scholar 

  32. 32.

    Emrich, H. M. et al. Sweat composition in relation to rate of sweating in patients with cystic fibrosis of the pancreas. Pediatr. Res. 2, 464–478 (1968).

    Google Scholar 

  33. 33.

    Ohara, K. Chloride concentration in sweat; its individual, regional, seasonal and some other variations, and interrelations between them. Jpn J. Physiol 16, 274–290 (1966).

    Google Scholar 

  34. 34.

    Coyle, S. et al. Textile sensors to measure sweat pH and sweat-rate during exercise. In Proc. 3rd International ICST Conference on Pervasive Computing Technologies for Healthcare 1–6 https://doi.org/10.4108/ICST.PERVASIVEHEALTH2009.5957 (ICST, 2009).

  35. 35.

    Oncescu, V., O’Dell, D. & Erickson, D. Smartphone based health accessory for colorimetric detection of biomarkers in sweat and saliva. Lab Chip 13, 3232–3238 (2013).

    Google Scholar 

  36. 36.

    Torrente-Rodríguez, R. M. et al. Investigation of cortisol dynamics in human sweat using a graphene-based wireless mHealth system. Matter 2, 921–937 (2020).

    Google Scholar 

  37. 37.

    Marriott, B. M. Food Components to Enhance Performance: An Evaluation of Potential Performance-Enhancing Food Components for Operational Rations (National Academic Press, 1994).

    Google Scholar 

  38. 38.

    Robson, P. J. et al. Effects of exercise intensity, duration and recovery on in vitro neutrophil function in male athletes. Int. J. Sports Med. 20, 128–135 (1999).

    Google Scholar 

  39. 39.

    Luger, A. et al. Acute hypothalamic–pituitary–adrenal responses to the stress of treadmill exercise. New Engl. J. Med. 316, 1309–1315 (1987).

    Google Scholar 

  40. 40.

    Koc, S. The acute effect of aerobic exercise on serum cortisol levels of athletes and sedentary individuals. J. Educ. Train. Stud. 6, 29–36 (2018).

    Google Scholar 

  41. 41.

    Hong, Y. J. et al. Multifunctional wearable system that integrates sweat-based sensing and vital-sign monitoring to estimate pre-/post-exercise glucose levels. Adv. Funct. Mater. 28, 1805754 (2018).

    Google Scholar 

  42. 42.

    Emaminejad, S. et al. Autonomous sweat extraction and analysis applied to cystic fibrosis and glucose monitoring using a fully integrated wearable platform. Proc. Natl Acad. Sci. USA 114, 4625–4630 (2017).

    Google Scholar 

  43. 43.

    Sessler, D. I. Temperature monitoring and perioperative thermoregulation. Anesthesiology 109, 318–338 (2008).

    Google Scholar 

  44. 44.

    Zhang, Y. et al. Battery-free, fully implantable optofluidic cuff system for wireless optogenetic and pharmacological neuromodulation of peripheral nerves. Sci. Adv. 5, eaaw5296 (2019).

    Google Scholar 

  45. 45.

    Yeung, C. et al. A 3D-printed microfluidic-enabled hollow microneedle architecture for transdermal drug delivery. Biomicrofluidics 13, 064125 (2019).

    Google Scholar 

  46. 46.

    Lopez-Ramirez, M. A. et al. Built‐in active microneedle patch with enhanced autonomous drug delivery. Adv. Mater. 32, 1905740 (2020).

    Google Scholar 

  47. 47.

    Webb, R. C. et al. Epidermal devices for noninvasive, precise and continuous mapping of macrovascular and microvascular blood flow. Sci. Adv. 1, e1500701 (2015).

    Google Scholar 

  48. 48.

    Ma, Y. et al. Relation between blood pressure and pulse wave velocity for human arteries. Proc. Natl Acad. Sci. USA 115, 11144–11149 (2018).

    Google Scholar 

  49. 49.

    Cho, H., Kim, H.-Y., Kang, J. Y. & Kim, T. S. How the capillary burst microvalve works. J. Colloid Interface Sci. 306, 379–385 (2007).

    Google Scholar 

  50. 50.

    Choi, J. et al. Soft, skin-mounted microfluidic systems for measuring secretory fluidic pressures generated at the surface of the skin by eccrine sweat glands. Lab Chip 17, 2572–2580 (2018).

    Google Scholar 

Download references

Acknowledgements

This work made use of the NUFAB facility of Northwestern University’s NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205), the MRSEC programme (NSF DMR-1720139) at the Materials Research Center, the International Institute for Nanotechnology (IIN), the Keck Foundation and the State of Illinois, through the IIN. J.U.K. and T.K. were supported by the Brain Research Program of the National Research Foundation (NRF) funded by the Korean government (MSIT; NRF-2019M3C7A1032076). J.C. acknowledges support from the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT; NRF-2019R1A2C1084419). J.A.R. acknowledge support from the National Institute on Aging of the National Institutes of Health (NIH R43AG067835). We thank the Querrey-Simpson Institute for Bioelectronics for support of this work.

Author information

Affiliations

Authors

Contributions

K.K., J.U.K. and J.A.R. conceived the idea, designed the research, analysed data and wrote the manuscript. K.K., J.U.K. and S.R.K. performed and were involved in the manufacturing of the sensors. K.K. designed the hardware for the wireless electronics platform. K.K., K.L. and I.Y. performed software design and software validation. Y.D. and Y.H. performed thermal and mechanical modelling. J.C., H.J., C.-J.S., Y.W., L.L., T.S.C., D.W. and J.-H.K. assisted with device fabrication. K.K. and J.U.K. performed research and led the experimental works with support from H.J., Y.P., T.K., R.G. and S.L.

Corresponding author

Correspondence to John A. Rogers.

Ethics declarations

Competing interests

J.A.R., S.L. and R.G. are cofounders and/or employees of Epicore Biosystems, Inc., a company that pursues commercialization of microfluidic devices for wearable applications.

Additional information

Peer review information Nature Electronics thanks Tolga Kaya, Christopher Proctor and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–21, Tables 1–3 and notes 1–4.

Reporting Summary

Source data

Source Data Fig. 1

Source data for Fig. 1c (inset).

Source Data Fig. 2

Source data for Fig. 2c–i.

Source Data Fig. 4

Source data for Fig. 4c–i.

Source Data Fig. 5

Source data for Fig. 5d,e.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Kwon, K., Kim, J.U., Deng, Y. et al. An on-skin platform for wireless monitoring of flow rate, cumulative loss and temperature of sweat in real time. Nat Electron 4, 302–312 (2021). https://doi.org/10.1038/s41928-021-00556-2

Download citation

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing