Assistant Professor of Mechanical and Environmental Engineering
Micro Fluids Research
Projects:
Instrumentation Development (Micro-resolution Particle Image Velocimetry)
Micro-resolution particle image velocimetry:
A novel particle image velocimetry technique is developed to measure flow fields in micro-fabricated fluidic devices. This technique extends the spatial resolution of conventional PIV techniques from ~ 1 mm down to approximately 3 - 10 microns. The velocimeter is used to characterize flow fields in micro-machined Silicon channels. Here, one can measure velocity vectors at several thousand points in a two-dimensional plane at one instant in time.
Recent advances in micro-machining technology has made it possible for the development of many new micro-fluidic devices for biomedical applications. It is important to have techniques which allow researchers to characterize flows in these devices. Two-dimensional velocity vector fields can be used to characterize better newly developed micro-fluidic devices, and help reduce the cycle time between successive design iterations. In addition, this velocimetry technique provides a method for real-time monitoring of the fluid processes at multiple points in micro-devices.
In the current research, velocity measurements are made by tracking the images of groups of ~100 nm dia. particles. The particle size is chosen large enough so that Brownian motion of the particles does not appreciably contribute to errors in the velocity measurements. The particles are chosen small enough so that the particles follow the flow faithfully, do not alter the flow field, and do not plug the micro-device. Images of the particles are captured and digitized with a large-format high-dynamic-range CCD camera. The resulting image fields are statistically analyzed to determine the most probable particle velocity, which is also the best estimate of the local fluid velocity. Thousands of particle images can be captured and analyzed simultaneously, thereby allowing one to measure several thousand velocity measurements on a 2-D plane at one instant in time.
This project investigates the physics of supersonic flow through microfabricated supersonic nozzles. These nozzles are 20 microns wide at the throat and are 100 microns in length. They are fabricated by Prof. Kenny Breuer's [http://raphael.mit.edu/BREUER.bio.html] research group at MIT.
Velocity measurements are conducted using PIV in the Micro-fluids laboratory at the University of California - Santa Barbara.
Particle Image Velocimetry is used to examine mixing processes in microfabricated
channels. Special geometries and boundary conditions are employed to enhance
mixing in the inherently laminar flows. Applications of this research include:
using microchannels for cooling of integrated circuits and diode lasers,
developing precision micro-mixing devices for the chemical and pharmaceutical
industries, and designing combustion chambers on a silicon chip.
Research Publications Instruction Students
Contact bennett@engineering.ucsb.edu with comments or questions.
Last Modified: June 3, 1997 - M. Jordan