Abstract
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 microL 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.