1. Micro-Fluidic Device for Antigen Discovery
By: Khine Lwin
August 23, 2007
Graduate Student: Armando Tovar
Professor: Dr. Abraham Lee

2. Background
Antigen: a foreign molecule that triggers an immune response upon entering the body
Antibody: a protein that attaches to antigens, tags them as foreign, and neutralizes them
Binding-specific
Obtained from Wikipedia.org

3. Purpose
Create a micro-fluidic device that can detect diseases quickly and efficiently
Faster than ELISA (takes about 24 hours)
Simple design
Diagnostics:
Detect serum concentrations
West Nile, HIV, Smallpox, bioterrorist threats, etc.
Detect food allergens
Device consists of:
Ti/Au electrode array
Micro-channel created using polydimethylsiloxane (PDMS)
H3L Proteins immobilized on electrode array
H3L, an intracellular mature virion envelope protein.
Figure 1. Micro-fluidic Device

4. Device Fabrication Photolithography Etch Au/Ti electrodes onto glass
Protein Spotting
Place droplets of H3L proteins onto electrode tips
PDMS
PDMS is used to create a micro-channel which will be sealed on top of the electrode gap

5. Photolithography
Figure 2. Photolithography Process

6. Protein Immobilization
Surface Printing Tip (SPT)
Nano Ware
Nano eNabler
Printing Process

7. System Equivalent Circuit Function Generator Current Amplifier DMM
Flow R
DAQ Computer AC
Device
Equivalent Circuit
Faradic Cage
Figure 5. Flowchart of System

8. Channel Cs Bulk Solution Rs Double Layer Antibody Diffusion layer CDL
Antigen
All of these components affect impedance
CIL
Immobile layer

9. Double Layer
CDouble Layer

10. Optimization

11. Experimental Procedure
Solution
Flow Rate
(µL/min)
Duration
(min)
Data
TTBS Washing Buffer 40
5 Wash
5 Measurements
Flow turned on/off for 50 seconds (x2)
Blocking Buffer 10 12
TTBS
Primary Antibodies 5 20
Secondary Antibodies
DI H20
Manual
Approx. 3
Figure 2. Flow chart of system
Table 1. Protocol for Testing Micro-fluidic Device 11

12. Results Talk about misalignment
Figure 6. Signal Response as Flow is Turned On and Off

13. Results

14. Confirmation of Antigen-Antibody Binding

15. PDMS Current Design 1x .5 mm Electrode Tips 200 µm PDMS channel
10 µm gap between the Electrode Tips
Figure 4. PDMS Channel Sealed on top of Electrode Tips

16. Future Work Improve LabVIEW program
Further research how channel alignment affects impedance
Improve methods for fluorescently tagging antibodies to confirm antigen-antibody binding
Antibodies are fluorescently tagged to not only track antigen-antibody binding, but also to prove that the two entities are bound together.

17. Special Thanks Dr. Abraham Lee Armando Tovar BioMint Lab IM-SURE
National Science Foundation
Said Shokair
Jason Choi & Lillian Shido
Any Questions?

18. Optimization Cont’d

19. LabVIEW Current Program: Prompt user to save file
Graph voltage root mean square
Extract data and calculate admittance
Save data to spreadsheet in Excel
Figure 7. User-interface of current LabView
program 19