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Microfluidics
&
The Field of
Bioengineering
What is Bioengineering?
• Engineering
emphasizes
applications in
science
• Engineering focuses
on the design of more
efficient, cost
effective, new, and
better tools and
processes
Bioengineering
• Bioengineering combines life sciences with
engineering design to produce new, more
efficient devices for use in many areas
– Diagnostic tests for disease (microchips)
– Environmental monitoring (biosensors)
– Medical devices/machinery (prosthetics)
– Military applications (sensors in fabric to monitor soldiers,
improved camouflage)
– Biomimetrics (applying biology concepts to artificial systems)
Microfluidics: Computer Revolution Analogy
 How did this happen?
 Semiconductor Microelectronics:


Shrinking transistors, higher densities
Electrons behave the same on the microscale as they do in big wires.
Transistor:
Electron Routing
What is microfluidics?
Major Difference: for fluids, the fundamental physical behavior
changes rapidly as the size scale is decreased.
Microfluidics:
Fluid Routing
?
What is microfluidics?
 Understanding microfluidic behavior
requires knowledge of math, physics,
chemistry & engineering.
 To name a few:



Fluid mechanics: How do fluids behave on a
small scale?
Electrostatics: What is the importance of
electricity, magnetism & charged particles ?
Materials Science: What are the best
materials for making microfluidic devices?
 Small dimensions cause some physical
phenomena that we often neglect to
become very important.
Microscales
Strand of human hair
10 mm
Microchannel
Caliper Life Sciences
What is microfluidics?
Essentially dedicated to miniaturized
plumbing & fluid manipulation
 Offers the possibility of solving outstanding issues for biology
 Enabling fluid automation to save time, increase efficiency and rival
electronic integrated circuits
GETTING PUMPED: Just the thing for getting a
global view of how a cell works
What is a Microfluidic Chip?
• made of silicon (PDMS)
• pattern is engraved into
chip
• inlet channels are punched
into the silicon
• it is attached to glass to
form closed channels
• fluids can flow through the
channels and interact
according to the chip
design
•
http://youtu.be/JIewub-bPKY
•
http://youtu.be/wm2JOuA8K1w
What are the Advantages of
Microfluidic Chips?
• Cost effective
• Less hazardous materials generated/used
• Sample collection is easier/less painful for
the patient
• More time efficient diagnostic tests
• Portable for use in outdoor settings/areas
without power supply needed for big
machinery
Digital Microfluidics: Bubble Logic
Instead of test tubes,
chemical reactions can be
also performed in droplets.
But how do we mix reagents
in droplets?
• Mixing in a straight channel [video]
• Mixing in a serpentine channel [video]
Prakash and Gershenfeld. “Microfluidic Bubble
Logic,” Science 315: 832-835 , 2007.
Lung-on-a-Chip
Biomimetic
microsystem
reproduces
functionality of
lung alveoli
without need
for lab animal
models for
drug screening
& toxicity
studies.
Huh et al. “Reconstituting organ-level lung functions on a chip, “ Science
328: 1662-1668, 2010.
Ingber lab at Harvard, Dan Huh
Lab-on-a-Chip
Micro Total Analysis Systems (µTAS)
 Protein analysis
 DNA techniques
 Drug efficacy studies
 Single cell analysis
 Diagnostics, sensors
[Burns, M.A. et al. "An Integrated Nanoliter DNA
Analysis Device," Science 282: 484-487, 1998.]
 Most importantly, integration of all components on
one device!
A Rapid Diagnostic Device
One step diagnostic from IBM Zurich: [Video]
Readout
Making Microfluidic Devices: PDMS
Poly(dimethylsiloxane) aka PDMS ≈ Jello for
bioengineers!
UV light
① Make a mold  via photolithography
② Put in the PDMS precursor
③ Bake to cure
④ Assemble microfluidic layers!
Source [NBTC: Nanobiotechnology Center - Cornell University]
Mask
How do you make a MF Chip?
1. Selecting channel
shapes from the
AutoCad generated
master
2. Pour PDMS slowly
over the master
MF Chip Fabrication (con’t.)
3. Put on hot plate in
order to get rid of
bubbles in the PDMS
4. Cut out chip from
mold, punch inlet
channels,& mount on
glass slide
Additional/supplemental slides
Denisin - UC Berkeley
What do microfluidic tools give us?
Thorsen et al., Science, 2002
What is bioengineering?
Designing and creating innovative technologies to advance
medicine & clinical research
Computational
biology determines
structure-function
relationships of proteins,
the workhorses of our
bodies
Hemoglobin model above
Regenerative medicine biodegradable mold seeded with
human bladder cells
“Lab on a Chip" sequence large
genomes quickly and
cost-effectively
AbioCor Artificial Heart
Microfluidic Devices
 Rapid analysis of samples using:
small volumes (μl  10-6 L)
 high sensitivity & specificity
 fast response time – minutes
 small device, portable
 low energy consumption
 real-time detection capabilities

Applications are broad: rapid medical
diagnostics, environmental monitoring,
detection of biothreats, basic research…
Thought Experiment #1:
 Does static
electricity have
more of an effect
in moving large
or small objects?
 Why is this true?
Feynman, 1960
Thought Experiment #2:
 What would it be like
to swim in a pool full
of honey?
 How would it be
different from
swimming in water?
 Why?
Feynman, 1960
Molecular Diffusion
Thermal motion of particles from an area of high
to low concentration to result in gradual mixing
tea diffusing into hot water 
Diffusion rate depends on:
fluid temperature & viscosity
size (mass) of the particles