Smartphone has been widely integrated with sensors, like test strips, sensor chips, and hand-held detectors, for biochemical detections thanks to its portability and
ubiquitous availability. Utilizing built-in function modules, smartphone is often employed as controller, analyser, and displayer for rapid, real-time, and point-of-care
monitoring, which can significantly simplify design and reduce cost of the detecting systems. The favourable analytical performance along with the wearable nature
of the wireless transceiver makes the new epidermal potentiometric sensing system attractive for continuous monitoring the sodium dynamics in human perspiration
during diverse activities relevant to the healthcare, fitness, military, healthcare and skin-care domains.