Micro-particle sorting using two-phase interdigitated electrokinetic arrays

This research presents the design and characterization of two-phase interdigitated electrode arrays for the electrokinetic transport and sorting of microparticles. An important area of microfluidics is the development of Lab-on-a-chip devices, which are capable of analyzing small fluid samples and performing functions such as content analysis and particle mixing, transport and separation.;I demonstrate bidirectional motion on two-phase interdigitated polysilicon arrays. I report significant differences in the frequency and phase responses of metal and polysilicon arrays with similar geometry, showing that the polysilicon arrays can produce motion in both directions by reversing the phase of the signals.;I demonstrate lateral sorting of particles into focused streams in continuous motion using a rectangular loop of two-phase interdigitated arrays. I demonstrate the ability to consistently focus an initially scattered suspension of mono-size polystyrene particles into a single narrow stream traveling around the loop. I also demonstrate the ability of the device to separate suspensions of spheres with different sizes into distinct streams according to size.;This work represents a significant contribution to the present body of knowledge in the field of electrokinetic particle transport and sorting. The devices presented here are simpler than current designs and also reveal modes of particle transport and sorting that have not previously been demonstrated.;In this thesis, I demonstrate long range particle transport using linear two-phase interdigitated metal arrays with symmetric electrodes and asymmetric electrode spacing. I report net motion of polystyrene spheres in liquid solution and characterize the dependence of particle velocity on frequency, potential and phase, showing consistency with previous experiments involving four-phase arrays.