The accurate measurement of potassium ion levels in biological samples is essential given the impact such ion levels have on many aspects of homeo-stasis. Normal potassium levels are important for the maintenance of heart and nervous system function. Traditionally, potassium ions have been measured in plasma or serum using ion-selective electrodes,...

Determination of consumption/secretion rates of single-cell resolution has great potential for delivering detailed insights into early onset and development of various disease states as well as drug and stimulus response. Due the lack of sensitivity of current technologies, this information is difficult to obtain. Single cell measurements in vivo are...