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Hussain et al. Soft Sci. 2025, 5, 21 https://dx.doi.org/10.20517/ss.2025.02 Page 13 of 19

designed to detect various analytes in sweat. The device is adhered to the human epidermis using medical-
grade, double-sided adhesive tape. A hole is precisely cut in the center of the adhesive tape to align with the
sweat collection chamber, ensuring direct sweat contact with the sensors. The protective sheet on the tape
can be easily removed prior to application on the skin, making it user-friendly and hygienic. Figure 4H
showcases the fully assembled soft wearable array biosensors, incorporating CLCN-IPN , CLCN-IPN ,
GOx
Lox
and CLCN-IPN urease optical sensor films. These films are engineered to selectively detect glucose, lactate, and
urea, respectively. The black hole in the center represents the sweat collection chamber, through which
sweat flows into the sensor reservoirs. This multi-analyte detection capability allows for comprehensive
monitoring of key biomarkers in human sweat, making the device suitable for real-time health monitoring
in a non-invasive manner. Figure 4I demonstrates the mechanical stability of the wearable device. Even after
undergoing significant deformations such as rolling and bending, the device returns to its original shape
without any structural damage or compromise in sensor performance. This robustness ensures the device
remains functional during daily activities, making it ideal for long-term, real-world applications. This soft,
flexible wearable biosensor array not only integrates advanced optical sensor films for real-time monitoring
but also offers high mechanical resilience and comfort for continuous wear, showcasing its potential for
next-generation health diagnostics.

Off-body artificial sweat analysis
The soft wearable array biosensor was tested using artificial sweat to simulate real-world sweat composition.
Two samples were prepared: Sample 1 contained C Glucose = 1 mM, C = 20 mM, and C Lactate = 20 mM,
urea
reflecting typical physiological concentrations found in human sweat [53-55] . These concentrations are
commonly observed under normal conditions, making Sample 1 an appropriate model for healthy human
sweat. The soft wearable array biosensor was mounted on a round PDMS layer, which was connected to a
syringe pump for controlled delivery of the artificial sweat. The artificial sweat from Sample 1 was injected
at a flow rate of 40 µL/min, which corresponds to the typical sweat flow rate from the epidermis during
moderate physical activity. This flow rate ensures an accurate simulation of natural sweating, allowing for
effective sensor calibration. After 7 min, the biosensor chip was fully saturated. The inset in Figure 5A
shows the biosensor 2 h after the start of the artificial sweat injection. At normal physiological
concentrations, the CLCN-IPN , CLCN-IPN , and CLCN-IPN urease sensors obtained a green color,
Lox
GOx
indicating stable performance. The Δλ observed for the CLCN-IPN , CLCN-IPN , and CLCN-IPN urease
PBG
Lox
GOx
sensors were 40, 63, and 71 nm, respectively, as shown in the UV-Vis spectra in Figure 5B. Sample 2, with
elevated concentrations of C = 50 mM and C Lactate = 50 mM, was designed to mimic conditions commonly
urea
associated with metabolic disorders, kidney dysfunction, or dehydration, where abnormal sweat
composition serves as a clinical indicator of disease. High lactate levels in sweat may indicate muscle fatigue,
hypoxia, or mitochondrial disorders, while elevated urea levels are often linked to renal impairment,
including chronic kidney disease, uremia, or imbalances in the body’s ability to excrete nitrogenous waste.
These abnormal concentrations can reflect disruptions in metabolic or renal function, offering insight into
underlying health conditions. The same experimental setup was employed for Sample 2, and the Δλ
PBG
values for the CLCN-IPN , CLCN-IPN , and CLCN-IPN urease sensors were 44, 169, and 140 nm,
Lox
GOx
respectively [Figure 5C]. These significant changes were readily observable, with the CLCN-IPN and
Lox
CLCN-IPN urease sensors turning from blue to orange-red, while the CLCN-IPN sensor remained green, as
GOx
shown in the inset of Figure 5C. The UV-Vis spectra corresponding to Sample 2 are displayed in Figure 5D,
clearly demonstrating the sensitivity of the biosensor array to elevated metabolite levels. This off-body
artificial sweat analysis demonstrates the ability of the soft wearable array biosensor to detect both normal
and pathological concentrations of key biomarkers, providing a visually distinguishable response through
colorimetric changes and measurable wavelength shifts in real time. This technology has potential
applications in non-invasive diagnostics, continuous health monitoring, and personalized medicine.