An Energy-Resolved Optical Non-invasive Device Detects Essential Electrolyte Balance in Humans at Point-of-Care.

Regular monitoring of electrolyte balance is essential for patients suffering from chronic kidney disease (CKD), particularly those undergoing dialysis. In the context of the recent COVID-19 pandemic, more severe forms of infection are observed in elderly individuals and patients having co-morbidities like CKD. The repeated blood tests for the monitoring of electrolyte balance predispose them not only to COVID-19 but also other to hospital-acquired infections (HAI). Therefore, a non-invasive method for easy detection of essential electrolyte (K + and Na + ) levels is urgently needed. In this study, we developed an optical emission spectroscopy-based non-invasive device for simultaneous monitoring of salivary Na +  and K + levels in a fast and reliable way. The device consisted of a closed spark chamber, micro-spectrometer, high voltage spark generator, electronic circuits, optical fiber, and an indigenously developed software based on the LabVIEW platform. The optical emission originating from the biological sample (i.e., saliva) due to recombination of ions energized by impingement of electrons returning from high voltage spark provides necessary information about the concentration of electrolytes. A small-scale clinical trial on 30 healthy human subjects shows the potential of the indigenously developed device in determining salivary Na  + and K + concentration. The low-cost, portable, point-of-care device requires only 2 mL of sample, and can simultaneously measure 1.0-190.0 mM Na + , and 1.0-270.9 mM K +  . To our understanding, the present work will find its relevance in combating COVID-19 morbidities, along with regular CKD patient-care.