88656
Techniques for Improved Pulse Shape for Particle Detection
Mark Villamor
Mentor: John LaRue & Richard Nelson
The Coulter counter is a technique for particle counting based on the resistance change that occurs when a particle in an electrically conducting fluid passes through a small opening or a channel. The pulse shape resulting from particle detection in Coulter Counters is highly variable. The variation in pulse shape results from the different flow paths of the particle relative to the electrodes. This limits the information that can be extracted from the waveform, such as the particle’s size and shape. Incorporating a new electrode configuration and hydrodynamic focusing of the particle flow can reduce this variability. The purpose of this project is to design and fabricate a microfluidic device that can successfully count and estimate particles with a diameter ranging from 5-10 microns. This is accomplished with the design of a symmetric electrode structure, hydrodynamic focusing, and an improved input coupling. The symmetric electrode structure reduces the variability of the generated pulse and hydrodynamic focusing centers the particles down the length of the channel. Both increase the symmetry of particle placement with respect to the electrodes, resulting in a more spatially uniform electric field distribution.