A Microfluidic Ion Sensor Array

Abstract

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.