Rapid Capture and Extraction of Sweat for Regional Rate and Cytokine Composition Analysis Using a Wearable Soft Microfluidic System

Sweat is a rich, heterogeneous biofluid that consists of electrolytes (e.g., sodium, chloride, potassium ions), micronutrients (magnesium ion, calcium iron, vitamin c), metabolites glucose, lactate, ammonia, urea), hormones cortisol, cytokines), and environmental toxins ethanol) (Baker et al., 2009Baker L.B. Stofan J.R. Hamilton A.A. Horswill C.A. Comparison regional patch collection vs. whole body washdown for measuring sweat sodium loss during exercise.J Appl Physiol (1985). 2009; 107: 887-895Crossref PubMed Scopus (109) Google Scholar, Baker Wolfe, 2020Baker Wolfe A.S. Physiological mechanisms determining eccrine composition.Eur J Physiol. 2020; 120: 719-752Crossref (36) Scholar). Biomarkers in provide insight about underlying physiological metabolic processes exhibit changes related to performance, wellness, health For example, chloride testing well-established routine clinical tool cystic fibrosis screening newborns (Gibson Cooke, 1959Gibson L.E. Cooke R.E. A test concentration the pancreas utilizing pilocarpine by iontophoresis.Pediatrics. 1959; 23: 545-549PubMed Mishra 2005Mishra A. Greaves R. Massie J. The relevance diagnosis genomic era.Clin Biochem Rev. 2005; 26: 135-153PubMed More recently, several studies have demonstrated efficacy potential as target monitoring drug levels levodopa) therapeutic dosing (Tai 2019Tai L.C. Liaw T.S. Lin Y. Nyein H.Y.Y. Bariya M. Ji W. al.Wearable band noninvasive levodopa monitoring.Nano Lett. 2019; 19: 6346-6351Crossref (50) Scholar), glucose diabetes management (Lee 2017Lee H. Song C. Hong Y.S. Kim M.S. Cho H.R. Kang T. al.Wearable/disposable sweat-based device with multistage transdermal delivery module.Sci Adv. 2017; 3e1601314Crossref (510) ethanol assess alcohol intoxication (Gamella 2014Gamella Campuzano S. Manso González de Rivera G. López-Colino F. Reviejo A.J. al.A novel non-invasive electrochemical biosensing situ determination content blood sweat.Anal Chim Acta. 2014; 806: 1-7Crossref (81) cortisol monitor stress (Torrente-Rodríguez 2020Torrente-Rodríguez R.M. Tu Yang Min Wang al.Investigation dynamics human using graphene-based wireless mHealth system.Matter. 2: 921-937Abstract Full Text PDF (87) lactate concentrations track hypoxia (Pribil 2014Pribil M.M. Laptev G.U. Karyakina E.E. Karyakin Noninvasive based on gene-free engineering oxidase analysis undiluted Chem. 86: 5215-5219Crossref (39) Quantitative composition currently relies on, first, capturing disposable gauzes, absorbent pads, or microtubes followed sample extraction through centrifuge gravimetric tools and, finally, off-site collected samples leveraging standard laboratory-based analytical techniques. Of these, steps are most prone introducing errors arising from contamination, evaporation, spillage, which affects measurement accuracy, especially small proteins cytokines (Dai 2013Dai X. Okazaki Hanakawa Murakami Tohyama Shirakata al.Eccrine contains IL-1?, IL-1? IL-31 activates epidermal keratinocytes danger signal.PLoS One. 2013; 8e67666Crossref (53) Katchman 2018Katchman B.A. Zhu Blain Christen Anderson K.S. Eccrine profiling immune biomarkers.Proteomics Clin Appl. 2018; 12e1800010Crossref (29) Thus, there critical need uncomplicated accurate wearable devices can readily capture point-of-care setting (Choi 2018Choi Ghaffari Rogers J.A. Skin-interfaced systems analytics.Sci 4: eaar3921Crossref (184) Ray 2019Ray T.R. Choi Bandodkar Krishnan Gutruf P. Tian L. al.Bio-integrated systems: comprehensive review.Chem 119: 5461-5533Crossref (369) Here, we present soft, skin-interfaced microfluidic facilitates rapid clean precise volumes into quantifiable cytokine analysis. patches were skin mounted healthy subjects (n = 10) collect excreted exposure heat (40–45 °C) controlled environment chamber. study protocol was approved Institutional Review Board Northwestern University (Evanston, IL) (IRB:STU00208494). Written informed consent obtained all subjects. Concentrations IL-1RA, IL-8 measured across three regions arms each subject diurnally (morning evening measurements) consecutive days (Supplementary Figure S1). These chosen because their direct inflammatory responses patients atopic dermatitis. analyzed an immunoassay, thereby robust platform tracking rate inflammation found sweat. Soft, platforms serve collection, storage, extraction, system well-suited intimate coupling biofluids remote settings. soft mounts directly achieve water-tight seal. 1a Supplementary S2 show exploded view multilayered device, highlighting intricate geometry ultrathin, impermeable microchannel layers. This six-layer polymeric design ultrathin external gases, limiting evaporation over days. unique material ideal trial at-home settings, where biosamples may require storage hours absence handling equipment. adhesion layer lies bottom surface incorporates area flow inlet port, turn connects overlying microchannel. port limited size (1–2 mm), significantly limits contamination issues owing sweat-to-skin contact prevalent more conventional devices. entering propagates it captured (Figure 1b c). length cross-sectional determine total volume given sweat-collection session. 1d shows forearms subject. magnified highlights key physical features epidermis microchannel, outlet port) real-time way visible staff. used rapidly extract cryovials analysis, without requiring other expensive equipment 1e f S3). To dependence concentrations, quantified sample. volumetric range extracted multiple 10–233 ?l. Linear regression demonstrates does not correlate IL-1? (y ?7.96× + 2,762; adjusted R2 0.08166) IL-1RA ?5.97× 3,449; ?0.001975) 2a). Furthermore, linear conducted ?0.0030× 1.425; 0.0720); however, near detection limit assay, making correlation difficult volume-versus-concentration results indicate IL-RA independent forearm Because plasma been shown vary diurnal cycles (Petrovsky 1998Petrovsky N. McNair Harrison Diurnal rhythms pro-inflammatory cytokines: regulation implications.Cytokine. 1998; 10: 307-312Crossref (226) Vgontzas 2005Vgontzas A.N. Bixler E.O. H.M. Prolo Trakada Chrousos G.P. IL-6 its circadian secretion humans.Neuroimmunomodulation. 12: 131-140Crossref (247) investigated whether similar phenomenon could be observed cytokines. pooled anatomic (upper left bilateral lower forearms) subgrouped time 2b). morning, median SD 789 ± 1,599, 2,639 2,797, 0.92 0.86 pg/ml, respectively. comparable those methods evening, 1,432, 2,340 3,021, 1.02 0.25 Wilcoxon rank-sum tests compare between morning collections. differences measurements statistically significant (P 0.0052) 0.042), whereas 0.59) not. Unlike plasma, location We different arm locations 2c). Kruskal–Wallis ANOVA no arm, right upper both (morning: P 0.58; evening: 0.97) 0.78; 0.81). 2 origins relative independence suggests produced glands rather than dissolved after being another mechanism keratinocytes). sweat, interstitial fluid, providing levels. presence such needs established measurements. lack 2c) consistency S1) consistent but day increases compared fluctuations levels, previous (Katchman Petrovsky Whether skin-specific role simply reflect variations requires additional larger populations disease subgroups, including dermatitis, urticaria, hyperhidrosis, autonomic thermal disorders. data support plots within this paper findings available corresponding author upon reasonable request. Jeffrey B. Model: http://orcid.org/0000-0003-3052-7076 Michael Z. Zhang: http://orcid.org/0000-0002-7485-8101 Adam Leech: http://orcid.org/0000-0003-3943-1097 Weihua Li: http://orcid.org/0000-0001-5660-5082 Melissa Seib: http://orcid.org/0000-0002-9528-0118 Shulin Chen: http://orcid.org/0000-0002-0280-1536 Jessica Wallace: http://orcid.org/0000-0002-2654-7149 Shin: http://orcid.org/0000-0002-8803-6862 Amay Bandodkar: http://orcid.org/0000-0002-1792-1506 Jungil Choi: http://orcid.org/0000-0002-3659-8978 Amy Paller: http://orcid.org/0000-0001-6187-6549 John Rogers: http://orcid.org/0000-0002-2980-3961 Shaui Xu: http://orcid.org/0000-0003-3560-6945 AJA, JBM, SPL, AL, WL, NR, MSS, SC, JW, JAR, RG cofounders and/or employees Epicore Biosystems, Cambridge, MA, company pursues commercialization applications. remaining authors state conflict interest. research funded LEO Science & Tech Hub . work utilized Micro/Nano Fabrication Facility. Conceptualization: ASP, SX, RG; Data Curation: MZZ, SPL; Formal Analysis: Investigation: JC, AJB, Methodology: JW; Writing - Original Draft Preparation: Editing: 30–45 minutes period two six these subjects, at around same (five one evening). others, session custom-built S2a) designed up ?200 ?l minimal S2b), applied positions arms. Subjects’ inner volar examined ensure they had intact skin. Subjects excessive hair application areas trimmed. cleaned sterile wipes allowed dry. Three proximal, distal, proximal 1d). entered sauna induce sweating. They enter leave ad libitum until 45 expired filled least 50 ?l, whichever came first. first completely full sufficient assay development. Times entry exit recorded. Once exited sauna, removed placed fixture S3a–c). gently wipe positioned labeled cryovial. Positive pressure pushed channel, out cryovial S3d). After closing vial, discarded, wipe. process repeated group. volume, scale zeroed empty differential weight vial measured. When fluid very low (?15 less), resulting sometimes zero negative variation among vials. Protease phosphatase inhibitor cocktails added 10% v/v. Vials then vortexed stored ?80 °C. prepared, shipped overnight dry ice bioassay laboratory (Pacific BioLabs, Hercules, CA) U-PLEX kits (Meso Scale Diagnostics, Rockville, MD). specifically series spike-recovery performed refine validate process. process, thawed centrifuged. supernatant diluted ratio 1:2 PBS raise pH. processed following instructions kit. Subject compared. In cases, higher Mean ratios (evening morning) 4.2 (range 1.4–5.8) 4.6 2.7–5.5). whom collected, rose day, fell again (IL-1?: 857–3,982–603 pg/ml; IL-1RA: 733–3,267–456 pg/ml). explore repeatability measurements, sequential purpose comparison, only (both evening) included. S1 highly correlated However, slope fit less (?0.57), indicating shift factor ?2 size.