Transcript Magnetic Separation Data - Research

Bacteria Counter
Wade May
Co-Advisors:
Dr. Todd Giorgio, Ph.D
Dr. Bob Galloway, Ph.D
Dept. of Biomedical Engineering
Copyright © 1999 Vanderbilt University
Problem/Market
• Chemical plants, treatment facilities, etc... have large
volumes of fluid traveling through piping systems.
– This fluid is always susceptible to bacterial
contamination.
• There is not a quick, cheap, and accurate way to
measure bacterial concentrations in these fluids.
– Current methods used take 24 hours to give an
estimate of bacterial concentrations.
– At large plants, 24 hours of unusable products can
represent a loss in excess of $100,000.
Dept. of Biomedical Engineering
Copyright © 1999 Vanderbilt University
Goals/Objectives
• Develop a simple, effective device that will measure
bacterial concentrations in an aqueous medium.
• The device should be relatively cheap (expensive
methods already exist).
• Measurements should be available in a short period
of time (less than 10 minutes).
• The device should perform its task with minimal or no
safety hazards.
Dept. of Biomedical Engineering
Copyright © 1999 Vanderbilt University
Current and New Methods
Current bacteria counters
Standard culture in petri dish
Sani-Check accelerated culture
Flow cytometer
Coulter counter
Aber capacitance measurement
Magnetic separation
Birefringence detection
Dept. of Biomedical Engineering
Time
Accuracy Expense
2-3 days
accurate
min
24 hours rough estimate min
< 10 min near exact
max
< 10 min near exact
high
< 10 min
?
?
< 10 min
?
low
< 10 min near exact moderate
Copyright © 1999 Vanderbilt University
Proposed Solutions
• Magnetic Separation
– Separate bacteria in a strong magnetic field and measure
the induced voltage due to their charge.
– This could be added online in a facility such as a chemical
plant.
– This device would be fairly inexpensive, safe, and could
provide real-time measurements.
• Detection of Birefringence
– Observe small sample of fluid under cross polarizers and
look for the birefringence of the cell membrane.
– Amount of light transmitted proportional to concentration of
bacteria in known volume.
– Quick optical method with no safety hazards.
Dept. of Biomedical Engineering
Copyright © 1999 Vanderbilt University
Work Completed
• Literature search.
• Faculty meetings and discussions.
• Magnetic Separation system design and prototype
construction.
• Preliminary testing with prototype.
• Birefringence Detection initial system design.
• Observation of bacteria under cross polarizers.
• Started image processing program.
Dept. of Biomedical Engineering
Copyright © 1999 Vanderbilt University
Birefringence Data
Original Image
Dept. of Biomedical Engineering
Processed Image
Copyright © 1999 Vanderbilt University
Magnetic Separation Data
• Successfully induced voltage due to separation of
ions in saline.
– Signal is very unstable and difficult to work with.
– Equipment is crude at best.
• Will attempt to detect red blood cells in the next
couple of days.
– Have increased gain from 120 to 1200.
– Will document with pictures.
Dept. of Biomedical Engineering
Copyright © 1999 Vanderbilt University
Future Work
• Magnetic Separation
– Test system with PBS.
– Test system with PBS and blood.
– Analyze data and design.
• Birefringence Detection
– Finish program to determine bacterial concentration.
– Consider details of the overall system design.
– Determine next steps to be taken.
• Construct Poster Presentation
• Write Final Paper
Dept. of Biomedical Engineering
Copyright © 1999 Vanderbilt University