A low temperature co-fired ceramic based microfluidic Clark-type oxygen sensor for real-time oxygen sensing

In this paper, a microfluidic platform for real-time monitoring of dissolved oxygen in a flowing microfluidic environment fabricated using low temperature co-fired ceramic (LTCC) technology is described. The fabricated Clark-type oxygen sensor consisted of three electrodes (working electrode, counter electrode and Ag/AgCl reference electrode), a solid-state proton conductive matrix (Nafion 117 membrane) and polydimethylosiloxane (PDMS) as the oxygen permeable membrane (OPM). The use of a solid-state proton conductive matrix as the electrolyte in the design of the oxygen sensor makes it feasible integrate this device in a typical LTCC fabrication process. Cyclic voltammetry and chronoamperometry measurement were used to characterize electrochemical properties of the developed oxygen sensor. The reduction current was linearly related with the dissolved oxygen concentration ranging from 0 to 8.1 mg/l under different flow conditions (0.0–1.0 ml/min). The residual currents of the oxygen sensor were less than 3.5% of that measured in oxygen saturated state, and the average response time was 10.9 s. The current device represents an improved Clark-type oxygen sensor with the advantages of easy fabrication, flexible configuration, fast response time, incorporation of microfluidic analyte introduction and real-time detection of dissolved oxygen. The potential applications include material synthesis, cell culture, biological assays incorporating controlled introduction of reagents or analytes and real-time monitoring of dissolved oxygen in a microfluidic environment.