A Microfluidic Ion Sensor Array.

A balanced concentration of ions is essential for biological processes to occur. For example, [H+] gradients power adenosine triphosphate synthesis, dynamic changes in [K+] and [Na+] create action potentials in neuronal communication, and [Cl-] contributes to maintaining appropriate cell membrane voltage. Sensing ionic concentration is thus important for monitoring and regulating many biological processes. This work demonstrates an ion-selective microelectrode array that simultaneously and independently senses [K+], [Na+], and [Cl-] in electrolyte solutions. To obtain ion specificity, the required ion-selective membranes are patterned using microfluidics. As a proof of concept, the change in ionic concentration is monitored during cell proliferation in a cell culture medium. This microelectrode array can easily be integrated in lab-on-a-chip approaches to physiology and biological research and applications.