Non-Invasive Sweat Biomarker Sensing

The SWEATSENSER device consists of a replaceable sweat sensing strip and an electronic reader. The sensing strip is functionalized with specific target capture probes, that is, IL‐6, IL‐8, IL‐10, and TNF‐α monoclonal antibodies as described previously. This sensor strip is mounted onto a wearable electronic reader that transduces the impedance response from the sensor and reports the measured biomarker levels in sweat. The sensor fabrication process has been adapted from Munje et al. and has been described in detail previously.⁴⁷ (link) Briefly, a sensing‐electrode system is fabricated on the SWEATSENSER strip for enabling transduction of affinity‐based interaction between the target biomarker and capture probe antibody into a measurable electrochemical signal. The sensor has been designed to handle low volumes of sweat and the design has been optimized by considering the sweat gland density, sweating rate, and surface area of contact. Non‐faradaic electrochemical impedance spectroscopy was used as the detection modality to determine the sensing response of the binding interactions between the specific capture probe and target molecule. A very low input of 10 mV sinusoidal voltage was applied to the sensing electrodes and the change in impedance due to the binding interaction between target molecule and capture probe antibody resulting in charge modulation was recorded at 180 Hz. Calibration curve for each study marker was developed by measuring the impedance response for varying concentrations of the target analyte over the physiological range of 0.2–200 pg mL⁻¹.