Ion Sensor for the Quantification of Sodium in Sweat Samples

We present the conception of an electrochemical sodium ion sensor for point-of-care sweat analysis. This flexible amperometric sensor was developed to quantify the amount of sodium ions in sweat (in real-time), alleviating the wait time, large sample size, possible contamination, and expensive analytical equipment associated with current diagnostic procedures requiring sweat analysis. This sensor is composed of a multiwall carbon nanotube (MWNT) functionalized nylon-6 mat, for a flexible yet conductive sensor. The MWNTs are then functionalized with a cyclo-oligomeric calixarene, which is shown to selectively form a supramolecular complex with sodium ions. Upon complex formation, the charge carriers are drawn away from the carbon layer, hence the current is impeded, and the sodium ion detection is prevalent at appropriate physiological ranges for healthy and ailing humans. In this paper, the optimization of MWNT and calixarene functionalization, as well as the selectivity and sensitivity of the sensor will be discussed.