Lab-on-Chip Flow Injection Analysis System without an External Pump and Valves and Integrated with an In Line Electrochemical Detector

Surface energy in small droplets can be used to drive samples through microchannels. When a sample fluid is spontaneously driven through a solution filled microchannel with liquid droplets on its entry (sample) and exit (reservoir) ports, it is termed as a passive pumping device. A passive pump driven microfluidic system integrated with microfabricated planar electrodes or electrode arrays (e.g., interdigitated electrode arrays or microband electrode arrays) can be considered as a manifold for flow injection analysis without an external pump and injector valve. Factors affecting the passive pump driven flow rate in a polydimethylsiloxane (PDMS)-glass hybrid microfluidic system, including the volume, viscosity, and surface tension of the sample solution and the tilt of the microfluidic channel, are analyzed. By placing 2 mu L of hexacyanoferrate (II) solutions at the entry port of the device, peak shaped transients were recorded. The peak heights showed linear dependence on the sample concentrations between 3 x 10(-7) and 10(-5) M.