Portable biosensor for monitoring cortisol in low-volume perspired human sweat

Abstract

A non-faradaic label-free cortisol biosensor was demonstrated using MoS2 nanosheets integrated into a nanoporous flexible electrode system. Low volume (1–5 μL) sensing was achieved through use of a novel sensor stack design comprised of vertically aligned metal electrodes confining semi-conductive MoS2 nanosheets. The MoS2 nanosheets were surface functionalized with cortisol antibodies towards developing an affinity biosensor specific to the physiological relevant range of cortisol (8.16 to 141.7 ng/mL) in perspired human sweat. Sensing was achieved by measuring impedance changes associated with cortisol binding along the MoS2 nanosheet interface using electrochemical impedance spectroscopy. The sensor demonstrated a dynamic range from 1–500 ng/mL with a limit of detection of 1 ng/mL. A specificity study was conducted using a metabolite expressed in human sweat, Ethyl Glucuronide. Continuous dosing studies were performed during which the sensor was able to discriminate between four cortisol concentration ranges (0.5, 5, 50, 500 ng/mL) for a 3+ hour duration. Translatability of the sensor was shown with a portable form factor device, demonstrating a comparable dynamic range and limit of detection for the sensor. The device demonstrated a R2 correlation value of 0.998 when comparing measurements to the reported impedance values of the benchtop instrumentation.

Regional and correlative sweat analysis using high-throughput microfluidic sensing patches toward decoding sweat

“…Traditional methods for sweat testing require off-body measurements in specialized settings by trained experts, preventing individuals from monitoring their health status immediately, independently, or routinely (11,12). By taking advantage of flexible and hybrid electronics (13)(14)(15)(16)(17), wearable sweat sensors address this limitation by enabling in situ sweat measurements with real-time feedback, creating potential for preventive care, timely diagnosis, and treatment (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)). Yet, wearable sweat sensor development has stagnated at the experimental and laboratory stage, largely due to an incomplete understanding of sweat dynamics and the physiological information carried in sweat.…”

Electrochemically Exfoliated High‐Quality 2H‐MoS2 for Multiflake Thin Film Flexible Biosensors

“…The results also improve by several orders of magnitude those obtained by traditional methods such as the enzyme‐linked immunosorbent assay and are similar to recent nanosensors with a more complicated fabrication process, offering a promising alternative for fast and low‐cost delivery and use in emergency situations or in remote areas. Comparable detection levels as well as sensing areas ( Table 1 ) were obtained by other recent electrical biosensors based on MoS 2 with more complex fabrication methodology, not flexible, or not tested down to such low bending radius (1 mm) . The biosensor also shows remarkable performance with similar or better limit of detection compared to other Ebola detection techniques, showing no particular drawbacks such as necessity of special safety facilities, labeling, or difficulties for miniaturization (see Table S2, Supporting Information).…”

Wearable Electronics Based on 2D Materials for Human Physiological Information Detection

“…The target molecules bound on the MoS 2 semiconductor can change the charges on the surface, leading to a variation of capacitive reactance or impedance. Based on this principle, Kinnamon et al have used the MoS 2 nanosheets modified by cortisol antibodies for cortisol monitoring in human sweat . Via the electrochemical impedance measurement, the sensor has demonstrated a dynamic detection range from 1 to 500 ng mL −1 and a limit detection of 1 ng mL −1 .…”