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Chronological Sweat Sensor Patch for Real-Time Human Molecular Biomarker Monitoring



OBJECTIVE: Human performance monitoring by developing a non-invasive system that chronologically captures sweat, measures sweat rate, blocks contaminants, conforms to skin, and continuously reports sweat biomarkers. 

DESCRIPTION: The consequence of degraded human performance is of critical importance not only to the department of defense (DoD) missions but also to the general population as well. For example, fatigue, both physical and mental, is a recurrent problem costing businesses an estimated $150 billion annually in loss of productivity (Institute of Medicine of the National Academies 2006). Caused by many factors such as sleep deprivation, persistent mental activity, and prolonged physical exertion, fatigue can have negative effects on a large range of individuals across many walks of life. Heat-injuries for Tri-Service trainees impose great risks as well. In the Air Force alone, more than 200 trainees per year experience a significant level of heat injury, resulting in substantial losses in training time, potential injury, decreased mission effectiveness, and loss of life. Therefore, the ability to non-invasively detect and mitigate the risks associated with individuals who are facing the challenges in physiological and cognitive performance without interfering their job duties is of grave importance. Sweat is an information-abundant medium. Earlier human subject studies on the levels of molecular biomarkers such as interleukin-6, neuropeptide-Y (NPY),[1] cortisol,[1] and brain-derived neurotrophic factor,[2] showed that their physiological concentrations can be related to the human cognitive levels. The mass spectrometry study performed to perspiration samples collected using commercial sweat patches on major depressive disorder and healthy human subjects indicates that the concentration of secreted cytokines and neuropeptides are possible indicators for the human cognition level.[3] Collectively, a sweat sensor patch metering sweat rate and detecting molecular targets including, but not limited to, peptides, small molecules, and/or volatile organic compounds, in the human perspiration can be a game changer to achieve an ultimate direct and minimally invasive human protection and performance monitoring. Obtaining days of continuous sampling of sweat from an identical dermal spot has proved challenging using conventional sweat collectors, resulting in inconsistencies of sample quantity, contaminants, and exact time stamping. Thus identical volumes of chronologically collected sweat sampling hardware is in great demand for the continuous monitoring of sweating and sweat biomarkers. This work seeks to develop a modular wearable sweat patch system that incorporates chronological sample collection and real-time sensor technologies for molecular biomarkers into a single device containing sweat sampling well, electronic sensor, transducer, and communication via wired/wireless power for successful operation. This system will be used to establish and monitor the frequency, magnitude, and chemical make-up of sweat and sweat molecular biomarkers in order to noninvasively monitor human performance. Accomplishing these goals can ultimately lead to development of a real-time, wearable sweat monitoring device that correlates human performance with threshold biomarker concentrations established to indicate physiological health and cognitive levels in the training and operational environment. 

PHASE I: The temporal collection of sweat will allow for monitoring changes in the sweat metabolome and proteome biomarkers as a test subject sweating progresses over time. The chronologically obtained sweat sample from a body/skin-conformal sweat patch enables one not only to analyze the biomarker profiles without intermittent sampling gaps, but also to provide an effective real-time sweat sensing platform that paces its response to the more precisely time-stamped samples. The chronological sweat sampling patch is to be developed and demonstrated in this Phase I. The objective is to develop microfluidic sweat patch system that 1) capture discrete volumes of sweat in a time-stamped chronological manner for at least 72hrs, 2) scale from 100s of nL to 100s µL total collected sweat volume per patch, 3) flexible to conform to the body, 4) leakage-free in both static and dynamic dermal setting, 5) expandable to construct a robust electrical/electrochemical/optical epidermal sensor platform, and 6) integrate the wireless power and communication means for the sweat data acquisition and log. 7) The sweat patch performance has to be evaluated with simulated sweat or its equivalents using the proposer’s own or commercially available testbeds that are strictly NOT involved with any human or animal subjects. 

PHASE II: Phase II should demonstrate, evaluate, and deliver repeatable and reproducible microfluidic sweat patch system that satisfy Phase I 1-7 requirements, and 1) contain multiple wells each collecting 50-100 uL sweat which can be removed from the device to facilitate laboratory-based sweat analysis 2) sized to fit within a disk dimension of 2 in diameter and 1/8 in thickness, 3) measure sweat rate per unit area of skin, 4) display real-time log of collected sweat in each well, 5) demonstrate capturing of biomarker targets including, but not limited to, peptides, small molecules, and/or volatile organic compounds using analytical instruments, such as mass spectroscopy, 6) block potential skin or non-skin contaminants by analyzing chromatograms, 7) use material that emits less than 1ppb of analytical contaminants during the 8hr or longer exposure to the sweat, 8) designed to perform without cross-contaminating from the chronologically collected sweat samples, and 9) integrate robust electrical/electrochemical/optical epidermal biomarker sensors that monitor one or more sweat biomarker levels (e.g. sodium, chloride, cortisol, or NPY). The offeror shall initiate contact with FDA representatives and provide a clear plan on how FDA clearance will be obtained. 

PHASE III: Phase III should demonstrate the manufacturing of real-time sweat and sweat-biomarker monitoring epidermal patches. The developed sweat patch tech is planned transitioning to a product used by Tri-Service members to obtain the biomarker signifying his/her cognitive levels, individual level chemical exposure data, hydration, and/or physiological status. Air Education and Training Command (AETC) and Air Combat Command (ACC) can be the potential near-term customer fielding the technology for trainee health and cognitive stress monitoring. Air Force Medical Support Agency/SG5M (AFMSA/SG5M) will be the vehicle to develop the acquisition strategy to continue the work and identify manufacturing capability of current technology developers and/or their partners who can handle the manufacturing of same depending on required number of devices. The end product can be dual/multiple use item of interest from both other non-DoD government agencies and private sectors like sports, biomedical, and personal care industry. Additionally, to expand the use of the device to medical diagnosis FDA medical device certification will be pursued by the offeror. 


1: Morgan Iii, C.A., Rasmusson, A.M., Wang, S., Hoyt, G., Hauger, R.L., and Hazlett, G.: ‘Neuropeptide-Y, cortisol, and subjective distress in humans exposed to acute stress: replication and extension of previous report’, Biological Psychiatry, 2002, 52, (2), pp. 136-142

2:  Rojas Vega, S., Strüder, H.K., Vera Wahrmann, B., Schmidt, A., Bloch, W., and Hollmann, W.: ‘Acute BDNF and cortisol response to low intensity exercise and following ramp incremental exercise to exhaustion in humans’, Brain Research, 2006, 1121, (1), pp. 59-65

3:  Cizza, G., Marques, A.H., Eskandari, F., Christie, I.C., Torvik, S., Silverman, M.N., Phillips, T.M., and Sternberg, E.M.: ‘Elevated Neuroimmune Biomarkers in Sweat Patches and Plasma of Premenopausal Women with Major Depressive Disorder in Remission: The POWER Study’, Biological Psychiatry, 2008, 64, (10), pp. 907-911

KEYWORDS: Sweat, Chronological Sampling, Sweat Collection, Epidermal Sensor, Sweat Biomarker Monitor, Sensor 


Dr. Steve Kim 

(937) 938-3718 

Dr. Jennifer Martin 

(937) 938-3788 

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