SLOCK (sensor for circadian clock): passive sweat-based chronobiology tracker

SLOCK is a human sweat based platform for circadian relevant biomarkers- cortisol and DHEA. It monitors passively expressed eccrine and apocrine sweat towards measuring and reporting cortisol and DHEA concentrations over multiple time points in humans. The sensor works on the principle of affinity based electrochemical detection. The novelty lies in the usage of a hybrid porosity platform for enhancing multibiomarker detection ability through sweat. The platform is the first demonstration of chronobiology tracking using multiple biomarkers supported by human subject based study. The sensor performance is evaluated on a set of six healthy human subjects, which are varied by age, gender, and ethnicity. Following this, the sensor performance is confirmed using ELISA, a commercially used diagnostic technique. From the results, it can be observed that the sensor is highly sensitive to the target biomarker concentrations in the physiological range of 8-141 ng ml^-1. The platform is also able to capture the biomarker rise and fall (i.e., going from a low concentration of 1 ng ml^-1 to a high concentration of 100 ng ml^-1 and back down to 10 ng ml^-1). This is reflected by a percentage change of cumulative sensor response by 10%, 20%, and 22%, respectively from baseline, for cortisol. Similarly for DHEA, the sensor shows sensitivity to rising and falling changes with percentage changes of 45%, 55%, and 56% for 1, 100, and 10 ng ml^-1 biomarker concentrations. This sensitivity is crucial in order to develop the circadian profile for the user. Thus, the sensor offers a first time demonstration of the potential of a passive self-monitoring approach for managing circadian abnormalities and is a good platform for tracking chronobiology.