Continuous Monitoring of CRP, IL-6, and Calprotectin in Inflammatory Bowel Disease Using a Perspiration-Based Wearable Device.

BACKGROUND: Wearable sensor devices represent a noninvasive technology to continuously track biomarkers linked to inflammatory bowel disease (IBD). We assessed the inflammatory markers associated with IBD in human perspiration. METHODS: Participants with IBD were monitored for 40 to 130 minutes with a proprietary wearable sensor device used to measure C-reactive protein, interleukin-6, and calprotectin. Sensor response using electrochemical impedance spectroscopy and serum samples were measured on the same day. The Mann-Whitney test was used to analyze the relationship between active and remission IBD in serum and perspiration, classified according to endoscopic reports and serum biomarker levels. Asynchronously collected fecal calprotectin from a subset of the population was similarly analyzed. RESULTS: A total of 33 subjects were enrolled. Expression of calprotectin was significantly elevated in the active cohort compared with the remission cohort in perspiration (P < .05; median = 906.69 ng/mL; active 95% confidence interval [CI], 466.0-1833 ng/mL; remission 95% CI, 328.4-950.8 ng/mL), serum (median = 1860.82 ng/mL; active 95% CI, 1705-2985 ng/mL; remission 95% CI, 870.2-1786 ng/mL), and stool (P < .05; median = 126.74 µg/g; active 95% CI, 77.08-347.1 µg/g; remission 95% CI, 5.038-190.4 µg/g). Expression of CRP in perspiration and serum was comparable between the active and remission cohorts (perspiration: P > .05; median = 970.83 pg/mL; active 95% CI, 908.7-992 pg/mL; remission 95% CI, 903.3-991.9 pg/mL; serum: median = 2.34 µg/mL; active 95% CI, 1.267-4.492 µg/mL; remission 95% CI, 1.648-4.287 µg/mL). Expression of interleukin-6 in perspiration was nonsignificant in the active cohort compared with the remission cohort and was significantly elevated in serum (perspiration: P < .05; median = 2.13 pg/mL; active 95% CI, 2.124-2.44 pg/mL; remission 95% CI, 1.661-2.451 pg/mL; serum: median = 1.15 pg/mL; active 95% CI, 1.549-3.964 pg/mL; remission 95% CI, 0.4301-1.257 pg/mL). Analysis of the linear relationship between perspiration and serum calprotectin (R2 = 0.7195), C-reactive protein (R2 = 0.615), and interleukin-6 (R2 = 0.5411) demonstrated a strong to moderate relationship across mediums. CONCLUSIONS: We demonstrate the clinical utility of perspiration as a noninvasive medium for continuous measurement of inflammatory markers in IBD and find that the measures correlate with serum and stool markers across a range of disease activity.

This work establishes the clinical utility of perspiration as a noninvasive, continuous marker for gut inflammation and demonstrates the ability to distinguish between active and inactive inflammatory bowel disease across perspiration, serum, and stool.

Longitudinal assessment of sweat-based TNF-alpha in inflammatory bowel disease using a wearable device.

Wearable devices can non-invasively monitor patients with chronic diseases. Sweat is an easily accessible biofluid for continuous sampling of analytes, including inflammatory markers and cytokines. We evaluated a sweat sensing wearable device in subjects with and without inflammatory bowel disease (IBD), a chronic inflammatory condition of the gastrointestinal tract. Participants with an IBD related hospital admission and a C-reactive protein level above 5 mg/L wore a sweat sensing wearable device for up to 5 days. Tumor necrosis factor-alpha (TNF-α) levels were continually assessed in the sweat via the sensor, and daily in the blood. A second cohort of healthy subjects without chronic diseases wore the device for up to 48 h. Twenty-eight subjects were enrolled. In the 16 subjects with IBD, a moderate linear relationship between serum and sweat TNF-α levels was observed (R2 = 0.72). Subjects with IBD were found to have a mean sweat TNF-α level of 2.11 pg/mL, compared to a mean value of 0.19 pg/mL in 12 healthy controls (p < 0.0001). Sweat TNF-α measurements differentiated subjects with active IBD from healthy subjects with an AUC of 0.962 (95% CI 0.894-1.000). A sweat sensing wearable device can longitudinally measure key sweat-based markers of IBD. TNF-α levels in the sweat of subjects with IBD correlate with serum values, suggesting feasibility in non-invasive disease monitoring.

Longitudinal monitoring of IL-6 and CRP in inflammatory bowel disease using IBD-AWARE.

There are limitations to monitoring modalities for chronic inflammatory conditions, including inflammatory bowel disease (IBD). Wearable devices are scalable mobile health technology that present an opportunity to monitor markers that have been linked to worsening, chronic inflammatory conditions and enable remote monitoring. In this research article, we evaluate and demonstrate a proof-of-concept wearable device to longitudinally monitor inflammatory and immune markers linked to IBD disease activity in sweat compared to expression in serum. Sixteen participants with an IBD-related hospital admission and a C-reactive protein (CRP) > 5 µg/mL were followed for up to 5 days. The sweat sensing device also known as IBD AWARE was worn to continuously measure CRP and interleukin-6 (IL-6) in the sweat of participants via electrochemical impedance spectroscopy. Serum samples were collected daily. A linear relationship between serum and sweat readings for CRP and IL-6 was demonstrated based on individual linear correlation coefficients. Pooled CRP and IL-6 serum-to-sweat ratios demonstrated improving correlation coefficients as serum cutoffs decreased. Between the first and last day of observation, significant and non-significant trends in serum CRP and IL-6 were observed in the sweat. Comparison of sweat measurements between the subjects with active IBD and 10 healthy subjects distinguished an inflamed and uninflamed state with an AUC of 0.85 (95% CI: 0.68-1.00) and a sensitivity and specificity of 82% and 70% at a CRP cutoff of 938.9 pg/mL. IBD AWARE wearable device holds promise in longitudinally monitoring individuals with IBD and other inflammatory diseases.

Passive sweat wearable: A new paradigm in the wearable landscape toward enabling "detect to treat" opportunities.

Growing interest over recent years in personalized health monitoring coupled with the skyrocketing popularity of wearable smart devices has led to the increased relevance of wearable sweat-based sensors for biomarker detection. From optimizing workouts to risk management of cardiovascular diseases and monitoring prediabetes, the ability of sweat sensors to continuously and noninvasively measure biomarkers in real-time has a wide range of applications. Conventional sweat sensors utilize external stimulation of sweat glands to obtain samples, however; this stimulation influences the expression profile of the biomarkers and reduces the accuracy of the detection method. To address this limitation, our laboratory pioneered the development of the passive sweat sensor subfield, which allowed for our progress in developing a sweat chemistry panel. Passive sweat sensors utilize nanoporous structures to confine and detect biomarkers in ultra-low sweat volumes. The ability of passive sweat sensors to use smaller samples than conventional sensors enable users with sedentary lifestyles who perspire less to benefit from sweat sensor technology not previously afforded to them. Herein, the mechanisms and strategies of current sweat sensors are summarized with an emphasis on the emerging subfield of passive sweat-based diagnostics. Prospects for this technology include discovering new biomarkers expressed in sweat and expanding the list of relevant detectable biomarkers. Moreover, the accuracy of biomarker detection can be enhanced with machine learning using prediction algorithms trained on clinical data. Applying this machine learning in conjunction with multiplex biomarker detection will allow for a more holistic approach to trend predictions. This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Biosensing.

Label free impedance based acetylcholinesterase enzymatic biosensors for the detection of acetylcholine.

Realtime monitoring of neurotransmitters is of great interest for understanding their fundamental role in a wide range of biological processes in the central and peripheral nervous system, as well as their role, in several degenerative brain diseases. The measurement of acetylcholine in the brain is particularly challenging due to the complex environment of the brain and the low concentration and short lifetime of acetylcholine. In this paper, we demonstrated a novel, label-free biosensor for the detection of Ach using a single enzyme, acetylcholinesterase (ACHE), and electrochemical impedance spectroscopy (EIS). Acetylcholinesterase was covalently immobilized onto the surface of gold microelectrodes through an amine-reactive crosslinker dithiobis(succinimidyl propionate) (DSP). Passivation of the gold electrode with SuperBlock eliminated or reduced any non-specific response to other major interfering neurotransmitter molecules such as dopamine (DA), norepinephrine (NE) and epinephrine (EH). The sensors were able to detect acetylcholine over a wide concentration range (5.5-550 µM) in sample volumes as small as 300 µL by applying a 10 mV AC voltage at a frequency of 500 Hz. The sensors showed a linear relationship between Ach concentration and ΔZmod(R2 = 0.99) in PBS. The sensor responded to acetylcholine not only when evaluated in a simple buffer (PBS buffer) but in several more complex environments such as rat brain slurry and rat whole blood. The sensor remained responsive to acetylcholine after being implanted ex vivo in rat brain tissue. These results bode well for the future application of these novel sensors for real time in vivo monitoring of acetylcholine.

Electrochemical Aptasensing for Lifestyle and Chronic Disease Management.

Over the past decade, researchers have investigated electrochemical sensing for the purpose of fabricating wearable point-of-use platforms. These wearable platforms have the ability to non-invasively track biomarkers that are clinically relevant and provide a comprehensive evaluation of the user's health. Due to many significant operational advantages, aptamer-based sensing is gaining traction.Aptamer-based sensors have properties like long-term stability, resistance to denaturation, and high sensitivity. Using electrochemical sensing with aptamer-based biorecognition is advantageous because it provides significant benefits like lower detection limits, a wider range of operations, and, most importantly, the ability to detect using a label-free approach. This paper provides an outlook into the current state of electrochemical aptasensing. This review looks into the significance of the detection of biomarkers like glucose, cortisol etc., for the purpose of lifestyle and chronic disease monitoring. Moreover, this review will also provide a comprehensive evaluation of the current challenges and prospects in this field.

A Proof-of-Concept Electrochemical Skin Sensor for Simultaneous Measurement of Glial Fibrillary Acidic Protein (GFAP) and Interleukin-6 (IL-6) for Management of Traumatic Brain Injuries.

This work demonstrates the use of a noninvasive, sweat-based dual biomarker electrochemical sensor for continuous, prognostic monitoring of a Traumatic Brain Injury (TBI) with the aim of enhancing patient outcomes and reducing the time to treatment after injury. A multiplexed SWEATSENSER was used for noninvasive continuous monitoring of glial fibrillary acidic protein (GFAP) and Interleukin-6 (IL-6) in a human sweat analog and in human sweat. Electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) were used to measure the sensor response. The assay chemistry was characterized using Fourier Transform Infrared Spectroscopy (FTIR). The SWEATSENSER was able to detect GFAP and IL-6 in sweat over a dynamic range of 3 log orders for GFAP and 2 log orders for IL-6. The limit of detection (LOD) for GFAP detection in the sweat analog was estimated to be 14 pg/mL using EIS and the LOD for IL-6 was estimated to be 10 pg/mL using EIS. An interference study was performed where the specific signal was significantly higher than the non-specific signal. Finally, the SWEATSENSER was able to distinguish between GFAP and IL-6 in simulated conditions of a TBI in human sweat. This work demonstrates the first proof-of-feasibility of a multiplexed TBI marker combined with cytokine and inflammatory marker detection in passively expressed sweat in a wearable form-factor that can be utilized toward better management of TBIs. This is the first step toward demonstrating a noninvasive enabling technology that can enable baseline tracking of an inflammatory response.

Insight into the Phylogeny and Binding Ability of WRKY Transcription Factors.

WRKY transcription factors (TFs), which make up one of the largest families of TFs in the plant kingdom, are key players in modulating gene expression relating to embryogenesis, senescence, pathogen resistance, and abiotic stress responses. However, the phylogeny and grouping of WRKY TFs and how their binding ability is affected by the flanking regions of W-box sequences remain unclear. In this study, we reconstructed the phylogeny of WRKY across the plant kingdom and characterized the DNA-binding profile of Arabidopsis thaliana WRKY (WRKY54) based on its W-box recognition sequence. We found that WRKY TFs could be separated into five clades, and that the functional zinc-finger motif at the C-terminal of WRKY appeared after several nucleotide substitutions had occurred at the 3'-end of the zinc-finger region in chlorophytes. In addition, we found that W-box flanking regions affect the binding ability of WRKY54 based on the results of a fluorescence-based electrophoretic mobility shift assay (fEMSA) and quartz crystal microbalance (QCM) analysis. The great abundance of WRKY TFs in plants implicates their involvement in diverse molecular regulatory networks, and the flanking regions of W-box sequences may contribute to their molecular recognition mechanism. This phylogeny and our findings on the molecular recognition mechanism of WRKY TFs should be helpful for further research in this area.

A machine learning-based on-demand sweat glucose reporting platform.

Diabetes is a chronic endocrine disease that occurs due to an imbalance in glucose levels and altering carbohydrate metabolism. It is a leading cause of morbidity, resulting in a reduced quality of life even in developed societies, primarily affected by a sedentary lifestyle and often leading to mortality. Keeping track of blood glucose levels noninvasively has been made possible due to diverse breakthroughs in wearable sensor technology coupled with holistic digital healthcare. Efficient glucose management has been revolutionized by the development of continuous glucose monitoring sensors and wearable, non/minimally invasive devices that measure glucose concentration by exploiting different physical principles, e.g., glucose oxidase, fluorescence, or skin dielectric properties, and provide real-time measurements every 1-5 min. This paper presents a highly novel and completely non-invasive sweat sensor platform technology that can measure and report glucose concentrations from passively expressed human eccrine sweat using electrochemical impedance spectroscopy and affinity capture probe functionalized sensor surfaces. The sensor samples 1-5 µL of sweat from the wearer every 1-5 min and reports sweat glucose from a machine learning algorithm that samples the analytical reference values from the electrochemical sweat sensor. These values are then converted to continuous time-varying signals using the interpolation methodology. Supervised machine learning, the decision tree regression algorithm, shows the goodness of fit R2 of 0.94 was achieved with an RMSE value of 0.1 mg/dL. The output of the model was tested on three human subject datasets. The results were able to capture the glucose progression trend correctly. Sweet sensor platform technology demonstrates a dynamic response over the physiological sweat glucose range of 1-4 mg/dL measured from 3 human subjects. The technology described in the manuscript shows promise for real-time biomarkers such as glucose reporting from passively expressed human eccrine sweat.

Temporal profiling of cytokines in passively expressed sweat for detection of infection using wearable device.

This work presents the viability of passive eccrine sweat as a functional biofluid toward tracking the human body's inflammatory response. Cytokines are biomarkers that orchestrate the manifestation and progression of an infection/inflammatory event. Hence, noninvasive, real-time monitoring of cytokines can be pivotal in assessing the progression of infection/inflammatory event, which may be feasible through monitoring of host immune markers in eccrine sweat. This work is the first experimental proof demonstrating the ability to detect inflammation/infection such as fever, FLU directly from passively expressed sweat in human subjects using a wearable "SWEATSENSER" device. The developed SWEATSENSER device demonstrates stable, real-time monitoring of inflammatory cytokines in passive sweat. An accuracy of >90% and specificity >95% was achieved using SWEATSENSER for a panel of cytokines (interleukin-6, interleukin-8, interleukin-10, and tumor necrosis factor-α) over an analytical range of 0.2-200 pg mL-1. The SWEATSENSER demonstrated a correlation of Pearson's r > 0.98 for the study biomarkers in a cohort of 26 subjects when correlated with standard reference method. Comparable IL-8 levels (2-15 pg mL-1) between systemic circulation (serum) and eccrine sweat through clinical studies in a cohort of 15 subjects, and the ability to distinguish healthy and sick (infection) cohort using inflammatory cytokines in sweat provides pioneering evidence of the SWEATSENSER technology for noninvasive tracking of host immune response biomarkers. Such a wearable device can offer significant strides in improving prognosis and provide personalized therapeutic treatment for several inflammatory/infectious diseases.

Tracking metabolic responses based on macronutrient consumption: A comprehensive study to continuously monitor and quantify dual markers (cortisol and glucose) in human sweat using WATCH sensor.

Wearable Awareness Through Continuous Hidrosis (WATCH) sensor is a sweat based monitoring platform that tracks cortisol and glucose for the purpose of understanding metabolic responses related to macronutrient consumption. In this research article, we have demonstrated the ability of tracking these two biomarkers in passive human sweat over a workday period (8 h) for 10 human subjects in conjunction with their macronutrient consumption. The validation of the WATCH sensor performance was carried out via standard reference methods such as Luminex and ELISA This is a first demonstration of a passive sweat sensing technology that can detect interrelated dual metabolites, cortisol, and glucose, on a single sensing platform. The significance of detecting the two biomarkers simultaneously is that capturing the body's metabolic and endocrinal responses to dietary triggers can lead to improved lifestyle management. For sweat cortisol, we achieved a detection limit of 1 ng/ml (range ∼1-12.5 ng/ml) with Pearson's "r" of 0.897 in reference studies and 0.868 in WATCH studies. Similarly, for sweat glucose, we achieved a detection limit of 1 mg/dl (range ∼ 1-11 mg/dl) with Pearson's "r" of 0.968 in reference studies and 0.947 in WATCH studies, respectively. The statistical robustness of the WATCH sensor was established through the Bland-Altman analysis, whereby the sweat cortisol and sweat glucose levels are comparable to the standard reference method. The probability distribution (t-test), power analysis (power 0.82-0.87), α = 0.05. Mean absolute relative difference (MARD) outcome of Ë·5.10-5.15% further confirmed the statistical robustness of the sweat sensing WATCH device output.

Label-Free Protein Glycosylation Analysis Using NanoMonitor-An Ultrasensitive Electrochemical Biosensor.

Glycans (oligosaccharide chains attached to glycoproteins) are a promising class of biomarkers, found in body fluids such as serum, saliva, urine, etc., that can be used for the diagnosis of disease conditions. Subtle changes in glycans resulting from altered glycosylation machinery have been reported during various diseases, including carcinogenesis. In this article, we detail protocols for the rapid, label-free analysis of glycans using a previously developed highly sensitive and selective electrochemical impedance spectroscopy-based biosensing diagnostic platform called "NanoMonitor." The glycosensor operation is based on the specific affinity capture of the target glycans on the sensor surface by glycan-binding proteins known as lectins. This glycan-lectin binding activity modulates the impedance of the electrical double layer at the buffer-electrode interface. Protocols for the preparation of glycoprotein samples and glycosylation analysis using NanoMonitor and lectin-based ELISA are described here. The data obtained using these protocols show that NanoMonitor is capable of distinguishing between glycoform variants of the glycoprotein fetuin and glycoproteins derived from cultured human pancreatic cancer cells with high sensitivity (orders of magnitude higher than lectin-based ELISA) and selectivity. The results obtained indicate that NanoMonitor protocols can be further developed to enable use of NanoMonitor as a handheld electronic biosensor device for routine multiplexed detection of glycan biomarkers from clinical samples. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Preparing the NanoMonitor surface for glycan biosensing Support Protocol: Synthesis of glycoform variants of fetuin Basic Protocol 2: Performing Electrochemical Impedance Spectroscopy (EIS) for analyzing glycoprotein structures.

On-demand lactate monitoring towards assessing physiological responses in sedentary populations.

Identification of diseases in sedentary populations on a timely basis before reaching a critical stage is a continuing challenge faced by emergency care centers. Lactate is a key biomarker for monitoring restricted oxygen supply essential for assessing the physiological responses of the user for clinical diagnostics. The novelty of this work is the development of a non-invasive, mediator-free, stick and remove biosensor for the on-demand measurement of lactate in passive sweat targeted towards sedentary populations. The conformable interface of the biosensors with skin can be engineered to extract relevant biochemical signals and quantify the in situ sweat biomarker levels. In this work, we demonstrate a highly sensitive and specific on-demand biosensor with a fabricated hybrid nanotextured Au/ZnO electrode stack embedded within a flexible nanoporous material to capture the temporal dynamics of passive sweat lactate. The biosensor exhibits a lactate specific response in human sweat with a 1 mM lower limit of detection and a wide dynamic detection range of 1-100 mM (R2 = 0.98). The proposed biosensor has a sensitivity of 8.3% mM-1 while selectivity studies reveal negative interactions with non-specific molecules. The sensor stability studies showed an ∼30% degradation in the lactate biosensing response over a 4-day duration when stored at 4 °C. Non-faradaic electrochemical spectroscopy is employed as the detection modality to quantify the enzymatic catalysis of sweat lactate at the electrode-sweat interface. Spectroscopic characterization techniques such as XPS, ATR-FTIR, and zeta potential measurements confirm the enzymatic assay binding efficacy on a qualitative scale.

Electrochemical impedimetric biosensors, featuring the use of Room Temperature Ionic Liquids (RTILs): Special focus on non-faradaic sensing.

Over the last decade, significant advancements have been made in the field of biosensing technology. With the rising demand for personalized healthcare and health management tools, electrochemical sensors are proving to be reliable solutions; specifically, impedimetric sensors are gaining considerable attention primarily due to their ability to perform label-free sensing. The novel approach of using Room Temperature Ionic Liquids (RTILs) to improve the sensitivity and stability of these detection systems makes long-term continuous sensing feasible towards a wide range of sensing applications, predominantly biosensing. Through this review, we aim to provide an update on current scientific progress in using impedimetric biosensing combined with RTILs for the development of sensitive biosensing platforms. This review also summarizes the latest trends in the field of biosensing and provides an update on the current challenges that remain unsolved.

Autonomous, Real-Time Monitoring Electrochemical Aptasensor for Circadian Tracking of Cortisol Hormone in Sub-microliter Volumes of Passively Eluted Human Sweat.

The proposed work involves the development of an autonomous, label-free electrochemical sensor for real-time monitoring of cortisol levels expressed naturally in sub-microliter sweat volumes, for prolonged sensing periods of ∼8 h. Highly specific single-stranded DNA (ssDNA) aptamer is used for affinity capture of cortisol hormone eluted in sweat dynamically. The cortisol present in sweat binds to the aptamer capture probe that changes conformation and modulates electrochemical properties at the electrode-buffer interface, which was studied using dynamic light scattering studies for the entire physiological sweat pH. Attenuated total reflectance-Fourier transform infrared spectroscopy and UV-vis spectroscopy were used to optimize the binding chemistry of the elements of the sensor stack. Nonfaradaic electrochemical impedance spectroscopy was used to calibrate the sensor for a dynamic range of 1-256 ng/mL. An R2 of 0.97 with an output signal range of 20-50% was obtained. Dynamic cortisol level variation tracking was studied using continuous dosing experiments to calibrate the sensor for temporal variation. The sensor did not show significant susceptibility to noise due to cross-reactive interferents and nonspecific buffer constituents. The performance of the developed aptasensor was compared with the previously established cortisol immunosensor in terms of surface charge behavior and nonfaradaic biosensing. The aptamer sensor shows a higher signal-to-noise ratio, better resolution, and has a larger output range for the same input range as the cortisol immunosensor. The feasibility of deploying the developed aptasensing scheme as continuous lifestyle and performance monitors was validated through human subject studies.

A Sweat-based Wearable Enabling Technology for Real-time Monitoring of IL-1ß and CRP as Potential Markers for Inflammatory Bowel Disease.

BACKGROUND: More than 1.2 million people in the United States are affected by inflammatory bowel disease (IBD). Inflammatory bowel disease has a natural course characterized by alternating periods of remission and relapse. Currently, disease flares are unpredictable as they occur in a random way. Further, current testing methods and practices lack the ability for real-time tracking of flares. There exists no technology that can be utilized for continuous monitoring of biomarkers, as most of these rely on samples such as blood, feces, and testing methods by which continuous monitoring is not feasible. Cytokines play a key role in IBD; the development, recurrence, and exacerbation of the inflammatory process are orchestrated by their levels in time and space. Cytokines are also present in sweat. We hypothesize that demonstrating real-time continuous monitoring of interleukin-1ß (IL-1ß) and C-reactive protein (CRP) may help create an enabling technology to track inflammation in IBD patients and identify flare-ups and assess efficacy of therapy. METHODS: A multiplexed SWEATSENSER was used for noninvasive continuous monitoring of interleukin-1ß and C-reactive protein in human eccrine sweat. Impedance spectroscopy was used to measure the sensor response. Sweat was collected using an FDA-approved PharmChek patch from 26 healthy human subjects to determine the levels of the 2 study inflammatory markers. Correlation analysis was performed for preclinical validation of the SWEATSENSER with ELISA as the reference method. On-body continuous monitoring measurements were performed on 20 human subjects using EnLiSense's SWEATSENSER wearable device for real-time monitoring studies. RESULTS: The sensor device can detect interleukin-1ß and C-reactive protein in sweat over a dynamic range of 3 log orders. Pearson correlation of r = 0.99 and r = 0.95 was achieved for IL-1ß and CRP, respectively, for the SWEATSENSER with ELISA. Bland-Altman results further confirmed a good agreement (mean bias of -0.25 and -3.9 pg/mL for IL-1ß and CRP, respectively) of the device with the reference method, demonstrating applicability of the device for real-time monitoring. Continuous on-body measurements were performed in 20 healthy human subjects for the detection of IL-1ß to establish the preclinical utility of the sensor device. The continuous on-body measurements in healthy cohort reported a mean IL-1ß concentration of ~28 pg/mL. Stable measurements for over continuous 30 hours was reported by the device. CONCLUSION: This work demonstrates the first proof-of-feasibility of multiplexed cytokine and inflammatory marker detection in passively expressed eccrine sweat in a wearable form-factor that can be utilized toward better management of inflammatory bowel disease. This is a first step toward demonstrating a noninvasive enabling technology that can enable baseline tracking of an inflammatory response. Furthermore, this is the first study to report and quantify the presence of CRP in human eccrine sweat.

Flex-GO (Flexible graphene oxide) sensor for electrochemical monitoring lactate in low-volume passive perspired human sweat.

In this work, a low volume, sweat lactate sensor functioning on passively expressed eccrine sweat was designed, fabricated and tested in human sweat and its performance was benchmarked against a standard reference; Lactate Plus meter. This novel sensor comprises of graphene oxide (GO) nanosheets integrated into a nanoporous flexible electrode system for low-volume (1-5 µL) ultrasensitive impedance based detection of lactate using non-faradaic electron-ionic charge transfer. Lactate oxidase (LOD) enzyme was immobilized on the surface of GO nanosheets towards developing an affinity biosensor specific to the physiological relevant range (4-80 mM) of lactate in perspired human sweat. Sensing was achieved by measuring impedance changes specific to lactate binding along the GO nanosheet interface using electrochemical impedance spectroscopy. The sensor demonstrated a dynamic range from 1 to 100 mM spiked in synthetic and human sweat with a limit of detection of 1 mM. A specificity study conducted using cortisol expressed in sweat revealed a negative response to the lactate oxidase. Continuous lactate sensing studies were performed during which the sensor was responsive to concentrations of lactate up to 138.6 mM. Correlation of the sensor response with actual lactate concentration (1.3-113.4 mM) was found to be 0.955.

Point-of-use sweat biosensor to track the endocrine-inflammation relationship for chronic disease monitoring.

AIM: The hypothalamic-pituitary-adrenal axis is involved in maintaining homeostasis by engaging with the parasympathetic nervous system. During the process of disease affliction, this relationship is disturbed and there is an imbalance driven response observed. MATERIALS & METHODS: By monitoring the two key components involved in these pathways, cortisol and TNF-α, the manifestations of chronic stress on the body's homeostasis can be evaluated in a comprehensive manner. This work highlights the development of an electrochemical detection system for the two biomarkers through human sweat. RESULTS: Limit of detection and dynamic ranges are 1 ng/ml, 1-200 ng/ml for cortisol and 1 pg/ml, 1-1000 pg/ml for TNF-α. CONCLUSION: This wearable system is designed to be a point of use, chronic disease self-monitoring and management platform.

A Combinatorial Electrochemical Biosensor for Sweat Biomarker Benchmarking.

Misclassification of an acute disease condition as chronic and vice versa by electrochemical sweat biomarker sensors can cause significant psychological, emotional, and financial stress among patients. To achieve higher accuracy in distinguishing between a chronic condition and an acute condition, there is a need to establish a reference biomarker to index the actual chronic disease biomarker of interest by combinatorial sensing. This work provides the first technological proof of leveraging the chloride ion content in sweat for a combinatorial sweat biomarker benchmarking scheme. In this scheme, the sweat chloride ion has been demonstrated as the reference/indexing biomarker, while sweat cortisol has been studied as the disease biomarker of interest. Label-free affinity biosensing is achieved by using a two-electrode electrochemical system on a flexible substrate suitable for wearable applications. The electrochemical stability of the fabricated electrodes for biosensing applications was studied by open-circuit potential measurements. Attenuated total reflectance-Fourier transform infrared spectroscopy spectra validate the crosslinker-antibody binding chemistry. Concentration-dependent analyte-capture probe binding induces a modulation in the electrical properties (charge transfer resistance and double-layer capacitance) at the electrode-sweat buffer interface, which are transduced by nonfaradaic electrochemical impedance spectroscopy (EIS). Calibration dose responses for the sensor for cortisol (5-200 ng/mL) and chloride (10-100 mM) detection were evaluated in synthetic (pH 6) and pooled human sweat (R2 > 0.95). The variation in the cortisol sensor response due to fluctuations in sweat chloride levels and the significance of reporting normalized biomarker levels were demonstrated to further emphasize the need for biomarker benchmarking in electrochemical sensors.

AWARE: A Wearable Awareness with Real-time Exposure, for monitoring alcohol consumption impact through ethyl glucuronide detection.

Here we demonstrate for the first time a dynamic monitoring of the ethanol metabolite ethyl glucuronide (EtG) for a more robust evaluation of alcohol consumption, compared to conventional methods. A wearable biosensor device capable of reporting EtG levels in sweat continuously via low power impedance spectroscopy is reported. The custom hardware was compared against a conventional benchtop potentiostat, and demonstrated comparable results in the application of EtG detection in low volume sweat. The device successfully differentiated three distinct EtG concentrations correlating to simulated drinking scenarios estimated to be 1, 2, and 3 standard U.S. drinks consumed over a duration of 60 min, with p < 0.0001. This device has the potential to enable moderate drinkers to engage in guided decision-making, based on objective data, to address the needs of alcohol-sensitive populations. The device also will serve as a tool for researchers to better understand and characterize the relationship between sweat EtG and consumed alcohol.