Investigation of using potentiostats and microfluidic devices for continuous ions detection

Abstract

In the light of the importance of the bedside patient monitoring system, a miniaturized, flexible, versatile, disposable and cost effective bedside patient continuous monitoring system is essential. Therefore, this research addresses the development of a cost effective and miniaturize continuous monitoring system. For electrochemical analysis, three potentiostats were used: EmStat, CheapStat and in house UTMStat. For lab-on-chip system, two models were proposed and their electrochemistry and pumping characteristics were studied. The 2 layers detection zone was developed through fused filament technology and replication moulding technique with a screen printed electrode attached together. It achieved the maximum flow rate of 0.30405 ml/min with resonance frequency of 20 Hz in micropump reverse direction. With the maximum frequency, the highest oxidation peak current of 15.86176 |iA in cyclic voltammetry measurement was achieved by 10 mM ferrocyanide ions at potential 0.25 V. The monolithic microfluidic device was developed through sticker masks fabrication and replication moulding technique with two screen printed electrodes attached beneath the inlets and the outlets of the micropump. It achieved the maximum flow rate of 0.19693 ml/min with resonance frequency of 10 Hz in micropump forward direction. With the maximum frequency, the highest oxidation peak current of 28.32518 |xA in cyclic voltammetry measurement was achieved by 10 mM ferrocyanide ions at potential 0.32 V. Additionally, the electrochemical investigation was extended by measuring the cyclic voltammetry measurements of chloride ions from a mixture by using EmStat and CheapStat. The highest oxidation peak was observed at 61.26875 |jA and 1.04400 |±A by using EmStat and CheapStat respectively at potential 0.13 V. Specifically, the monolithic microfluidic device is well integrated in lab-on-chip system with the advantage of miniaturize with the dimensions of 41 mm x 26 mm, cost effective by using sticker masks fabrication and replication moulding technique, disposability since it is inexpensive and meant for biomedical analysis, flexibility where it can be used for other ions detection just by changing the screen printed electrode and can measure the data during pumping. This research successfully provides an alternative approach for continuous monitoring of ferrocyanide and chloride ions detection via cyclic voltammetry and amperometry measurements.