Harnessing Microfluidics for Research and Development

Nathaniel C. Cady

Asst. Prof. Nanobioscience

College of Nanoscale Science & Engineering

Outline

• Fluid dynamics (for non-majors)

• Building microfluidic devices

• Examples of research devices

Turbulent Flow

Laminar Flow

Re = (density) x (velocity) x (diameter) (viscosity)

If Re = 3000 or higher = turbulent flow

If 2000-3000 = transitional flow

If less than 2000 = laminar flow

2300 = transition point

Reynolds Number

Flow regime is predictable!

d

v

Microfluidic devices capitalize on small channel sizes to control flow regime

Advantages of Microfluidic Devices

• Well-controlled fluid dynamics

•Diffusion-limited mixing

•Controllable fluid interactions

• Small fluid volume

•Less sample and reagent needed

•More samples per unit area (multiplexing)

Microfluidics = “Lab-on-a-chip”

Device Fabrication

Fabrication of Microfluidic Devices

• Fabrication schemes range from simple to highly complex

• Primarily rely on micro / nanofabrication techniques

• Lithography (photo-, electron beam, imprint)

• Etching or molding of 3-D channels

• “Capping” or enclosure of channels

Photolithography

Transfer Pattern

Develop Resist

Etch substrate

Remove Resist

Making a Microfluidic Device

Direct Indirect

Fabrication is relatively easy…

Practical Applications

Diagnostics

Integrated DNA Purification & Real-Time PCR

35mm

20 m

m

Microchip-based DNA Biosensor

GuSCN (lysis buffer)

EtOH (wash buffer) dH2O (elution buffer)

DNA-based Diagnostics

10 microns

Micropillars for DNA Purification

Integrated Control System

Category Organism / Target DNA Purification Real-Time Detection Detection Limit

Bacteria Salmonella typhimurium Yes Yes 10 cells

Bacillus anthracis (Sterne) Yes Yes 40 cells

Listeria monocytogenes Yes Yes 100 cells

Staphylococcus aureus Yes Yes --

Escherichia coli Yes Yes --

Bacillus globigii (subtilis ) Yes Yes --

Phage Lambda Yes Yes --

Parasites Leishmania donovani Yes Yes --

Human CYP3A56 (SNP) Yes Yes --

ABCA1 (SNP) Yes Yes --

Amelogenin (SNP, gender) Yes Yes --

Cady et. al. (2005) Sensors & Actuators B. 107(1): 332-341

Cady et. al. (2003) Biosensors & Bioelectronics. 19: 59-66

Detection Results

Practical Applications

Micro Printing & Patterning

30 microns

Biomolecular Printing

PEG Hydrogel

Glass

GoldSiO2

Signaling ?

With Dr. Bill Shain & Dr. Matt Hynd – Wadsworth Center, NYS Dept. of Health

Probing Neural Networks

Biomolecular Printing

Insert movie

Microelectrode Array (MEA) Hydrogel-coated MEA patterned with the

laminin peptide, biotin-IKVAV. The laminin peptide biotin-IKVAV was printed onto using the automated NanoEnabler bioprinter. Printed peptide was arranged in a pattern consisting of orthogonal 2 mm-wide lines connecting 10 mm diameter node.

200um

• Microelectrode arrays (MEAs) coated with PEG-based hydrogel

• NeN used to pattern hydrogel with FITC-labeled bioactive peptides

• Successful printing of both spots and lines

Courtesy of: Matthew Hynd, PhD – NYS DOH

Printed Guidance for Neural Networks

Patterned neuronal network at 2 weeks in vitro. Primary hippocampal neurons were plated onto patterned arrays at a density of 400 cells/mm2.

Scanning electron microscope image of patterned neural network.

200um

• Printed MEAs seeded with primary hippocampal neurons

• Cells proliferated on the arrays and formed neural network on MEAs

• Results were comparable to studies using microcontact printing methods (Hynd, et. al., J. Neuroscience Methods, 2006)

Courtesy of: Matthew Hynd, PhD – NYS DOH

Neural Networks

Slow, difficult High acceleration / thermal exposure – potentially damaging to cells

Cellular Printing

Fluid Reservoir

Channel

Printing Tip

Polymeric Surface Patterning Tool

• Developed at CNSE, UAlbany (Cady Lab)

• Designed to enable live cell printing directly onto solid surfaces

• Larger channels and cantilever allow for whole cells to be printed

30 microns

BioForce Silicon-based SPT

Polymeric SPT

Direct Cell Printing

E. coli pET28A-GFP on polystyrene

100um100um

20 μm 20 μm 20 μm

Bacterial Cell Printing

E. coli pET28A-GFP TSA Plate (12 hr)

100um

Mouse MTLn3-GFP (diluted) printed on polystyrene

50 μm

Mammalian Cell Printing

Practical Applications

Cell Dynamics

O2 Input

Tumor Cell Input

Weir Structures

(Constrictions)

Collection Area

Output

1000µm

Cell

Weir Structures

(Constrictions)

Biomimetic Device for Tumor Cell Dissemination Studies

500µm

Device Filled with Dye

Fluid Flow Direction

Flow Cell Design

Units: (cm/sec)

500µm

Fluid velocity vectors

Fluid Dynamic Modeling

Flu

id F

low

100um

HEp3 Cells

(Human Epidermal Carcinoma 3)

Device Testing

Cells were smaller than anticipated – needed different weir spacing!

100um

Flu

id F

low

Rapid Prototyping of New Device

• Microfluidic devices reduce sample volume and offer unique fluid dynamic environments

• Novel fluid dynamics can affect reaction rates, diffusion, biological processes

• Practical applications (like patterning) can be accomplised using microfluidics

• Novel fluid environments can be used for biomimetic studies

Summary

Acknowledgements University at Albany Mt. Sinai

Dr. Robert Geer Dr. Julio Aguirre-Ghiso

Dr. Magnus Bergkvist

Dr. Alain Kaloyeros

Research Support

UAlbany Startup Funds

UAlbany FRAP A&B Awards

BioForce Instruments

CNSE / CAS Challenge Grant