On-chip Extraction of Blood Plasma Using Dielectrophoresis and Micropore Array

Abstract

This paper presented the effectiveness of dielectrophoresis (DEP) and micropore array on the microfluidic device as part of diagnostic sensors. The optimized structure of the device and its fabrication process were reported as well. Lots of attempts were made to get higher efficiency of the experiment such as to derive maximum DEP force, to extract liquid through the pore, to decrease running time etc. Dielectrophoresis and micropore array membrane, two main techniques were simultaneously but independently operated with an on-chip microfluidic platform. To generate DEP force, electrode arrays which induces non-uniform electric field was required. On a device, especially around the area where electrodes exist, there are four membranes that each have thousands of microsized pores, which permit blood plasma to pass downward. These electrode and pore array were constructed on a silicon nitride wafer using MEMS fabrication process. This fabrication process included photolithography, reactive-ion etching (RIE), physical vapor deposition (PVD), wet etching using KOH solution etc. The optimized shape of electrode was decided among various samples after testing motion of particles and surface treatment was also applied on membrane area to improve throughput of pores. The microfluidic channels were attached on both sides of the device. The experiment was progressed in the way of estimation based on theoretic equations. Micro-sized beads were also tested prior to main experiment in order to determine a more specific tendency of cells motion induced by negative DEP. It was eventually possible to extract blood plasma from a small amount of diluted whole blood only with a low voltage source for operating DEP.