Micro-Fluidic Device for Antigen Discovery

By: Khine LwinAugust 23, 2007Graduate Student: Armando TovarProfessor: Dr. Abraham Lee

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

Obtained from Wikipedia.org

Purpose• Create a micro-fluidic device that can detect

diseases quickly and efficiently

Figure 1. Micro-fluidic Device

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

Device Fabrication

Photolithography

Figure 2. Photolithography Process

Protein Immobilization

Nano eNabler

Surface Printing Tip (SPT)

Nano Ware

Printing Process

System

Figure 5. Flowchart of System

Function Generator

Current Amplifier

DMM

Flow

R

DAQ ComputerAC

Current Amplifier

Device

Equivalent Circuit

Faradic Cage

Channel

Antigen

Antibody

Immobile layer

Diffusion layer

Rs

Cs

CDL

CIL

Double Layer

CDouble Layer

Optimization

Experimental Procedure

Figure 2. Flow chart of system

Solution Flow Rate(µL/min)

Duration(min)

Data

TTBS Washing Buffer

40 5 Wash5 Measurements

Flow turned on/off for 50 seconds (x2)

Blocking Buffer

10 12

TTBS 40 5 Wash5 Measurements

Flow turned on/off for 50 seconds (x2)

Primary Antibodies

5 20

TTBS 40 5 Flow turned on/off for 50 seconds (x2)

Secondary Antibodies

5 20

TTBS 40 5 Wash5 Measurements

Flow turned on/off for 50 seconds (x2)

DI H20 Manual Approx. 3

Table 1. Protocol for Testing Micro-fluidic Device

Results

Figure 6. Signal Response as Flow is Turned On and Off

Results

Confirmation of Antigen-Antibody Binding

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

Future Work

• Improve LabVIEW program

• Further research how channel alignment affects impedance

• Improve methods for fluorescently tagging antibodies to confirm antigen-antibody binding

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

Any Questions?

Optimization Cont’d

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