Microfluidics and Lab-on-a-chip systems Pelle Ohlsson pelle.ohlsson@bme.lth.se
Today Who am I? What is microfluidics? What is the concept Lab-on-a-chip systems? What happens when you scale things down? Some applications of this
What is microfluidics?
What is a fluid?
What is micro?
What is micro? mc3cb.com, islandweavings.blogspot.se, en.wikipedia.org/wiki/blood
What is micro? reverseosmosis.co.uk, redorbit.com, webbofscience.com, www.imt.kit.edu
Miniaturization + Faster + Cheaper + Portable + Less manual work + Less consumption (power) Pictures: www.wikipedia.org
Miniaturization Lab-on-a-chip: + Faster + Cheaper + Portable + Less manual work + Less consumption (sample, chemicals) + New things possible Pictures: www.wikipedia.org, www.gene-quantification.de
Miniaturization Lab-on-a-chip: Capillary electrophoresis (CE) + Faster + Cheaper + Portable + Less manual work Microchip electrophoresis (MCE) + Less consumption (sample, chemicals) + New things possible Pictures: www.uni-saarland.de, www.gene-quantification.de
Microfluidics around us? www.bestinfographics.co, companionplants.com
What happens when you scale things down?
Fluid mechanics at the microscale L Surface-to-volume ratio: SSSSSSS VVVVVV L2 L 3 = 1 L Surface effects Mass Momentum Adhesion Volume effects Kinetic energy Viscosity
Reynolds number viscosity hydraulic diameter e.g. dimension, typical velocity typical density Re cos 2 2 = = = = = + = + η ρ η ρ η ρ ρ L u L u x u x p x u u t u ity vis j j i effects inertial i j i i i F
Reynolds number High Reynolds number (~ >2500) turbulent flow http://www.ims.ut.ee/~alar/microtech/ch1_2/ http://www.azimuthproject.org/azimuth/show/blog+-+eddy+who%3f
Reynolds number Low Reynolds number (~ <1500) laminar/creeping/stokes flow Re 10-11 Weibel et al. Analytical Chemistry, Vol. 77, No. 15, August 1, 2005 ChemPhysChem 2008, 9, 2140 2156, http://www.bbc.co.uk/science/earth/water_and_ice/glacier
Reynolds number Low Reynolds number (~ <1500) laminar/creeping/stokes flow Vortices may still form in the cavities!
Video: Laminar flow http://www.youtube.com/watch?v=bixvgu1ud_c&feature=relmfu
Pressure driven flow in circular channels r Q = V t = 4 πr0 8η L p
Mixing
Laminar flow and diffusion d = 222 M. Evander & M. Tenje (2013)
Lamination
Chaotic micromixer G.M. Whitesides et al Science Vol 295 25 Jan. 2002 647
Chaotic micromixer G.M. Whitesides et al Science Vol 295 25 Jan. 2002 647
Chaotic micromixer Straight channel Herring bone Slanted grooves G.M. Whitesides et al Science Vol 295 25 Jan. 2002 647
How can you move liquids?
Syringe pumps www.cetoni.de
Peristaltic pumps www.bluwhite.com cnzhidan.en.made-in-china.com reefbuilders.com www.checkmateuk.com
Capillary forces
Paper microfluidics http://spie.org/x43433.xml
4castchip https://www.youtube.com/watch?v=swfajszd27a 0:30 www.fiomi.se
Pressure driven flow
Gravitaty www.diagnoswiss.com springer.com
Centrifugal forces http://www.gyros.com/products/products-optimized/technology/ www.gyros.com
Electrowetting http://microfluidics.ee.duke.edu//
Electrowetting Abdelgawad et al. Lab Chip, 2008, 8, 672 677
Droplets Two phase systems https://www.youtube.com/watch?v=2sgxwc3w1dc 0:30
Electroosmosis O - H + OH O - H + Si Si Si Deprotonation of silanol groups Glass
Electroosmosis Electroosmotic mobility: µ eo = v eo E Can be modified by: Bulk electrolyte - ph - coating - voltage applied to substrate Diffuse layer Fixed layer Channel wall
Electroosmotic flow Pressure driven flow p 0 +Δp p 0
Electrophoresis v ep v eo v ep v eo v tot v tot v eo N v tot - Separation depending on the ratio between charge and viscous drag
Chemical separations
Spiral chips: 10-20 cm separation channels 24 mm 17 mm
Spiral chips: 10-20 cm separation channels Filters 24 mm 17 mm
Electrokinetic valving gated injection 24 mm 17 mm
NeuroTAS June 2008 Spiral chips: 10-20 cm separation channels 24 mm Separation channel 17 mm 46 / 36
Spiral chips: 10-20 cm separation channels 10 μm 20 μm 24 mm Separation channel 30 μm 40 μm 17 mm
Spiral chips: 10-20 cm separation channels 24 mm Detection cell 17 mm
Absorbance detection A = εvs Problem: short pathlength Solution: detection in plane
Visual absorbance detection Pregnancy test
Visual absorbance detection Allergy test http://www.youtube.com/watch?v=1vnpasvfvec 1.25
Fluorescence detection Epifluorescence detection Laser Detector Detection at an angle
Fluorescence detection Confocal fluorescence detection
Fluorescence detection Confocal fluorescence detection Even single molecules can be detected! Single DNA molecule (6 pm) stained with YOYO-1
Fluorescence detection Increased interaction length using waveguides
Fluorescence detection Integration of dye laser and photo diodes S. Balslev et al. Lab. Chip., 2006, 1, 213-217
Counting cells
Why count cells?
Flow cytometry Counting beads RBCs Platelets E coli http://www.semrock.com
Imaging cytometers www.amnis.com
Flow cytometry www.bdbiosciences.com Lab Chip, 2012, 12, 118-126
Fluorescence activated cell sorting (FACS) http://www.bio.davidson.edu/genomics/method/facs.html
Electrical cell counting
Cell counting and sizing Coulter counter A
Impedance spectroscopy Impedance measurement from khz to MHz E.g. counting and identification of cells Holmes, D. et al, IEEE Sensors 2007, 1452-1455.
Impedance spectroscopy Impedance measurement from khz to MHz E.g. counting and identification of cells Holmes, D. et al, IEEE Sensors 2007, 1452-1455. Holmes, D. et al, IEEE Sensors 2007, 1452-1455.
Sorting cells using sound
Kundt s tube in a microchannel?
Kundt s tube in a microchannel? Piezoelectric transducer w = n λ 2 Laurell et al, Chem Soc Rev (2007) wikipedia.org
Effect of contrast factor φ = 1 k 3 ρ 1 + 2ρ + 1 Positive => node Negative => anti-node k ρ = relative compressibility = relative density of particle with respect to fluid
Blood from heart surgery H. Jönsson et al, SocThorSurg (2004)
Blood from heart surgery
Sepsis
Primary axial acoustic radiation force F r = 4πr 3 E aa k sss 222 φ β, ρ r F r f F r Contrast factor φ = 1 k 3 ρ 1 + 2ρ + 1 F r = acoustic radiation force E ac = acoustic energy density r = particle radius k = wave number (2π/λ) x = particle distance to the node k ρ = relative compressibility = relative density of particle with respect to fluid
Separating bacteria from blood
Inlet Outlet
Acoustic trapping Flow Transducer
Separation, enrichment and PCR of bacteria from blood
Separation, enrichment and PCR of bacteria from blood
Reading DNA and RNA
Why read DNA and RNA?
http://users.ugent.be/~avierstr/principles/pcr.html
PCR chip www.abacusdiagnostica.com
Continous flow PCR Y. Zhang, P. Ozdemir / Analytica Chimica Acta 638 (2009) 115 125
DNA in nanochannels The persistence length (P) of dsdna is typically ~50 nm. DNA confinement in nanochannels: physics and biological applications, Walter Reisner, Jonas N Pedersen and Robert H Austin, Reports on Progress in Physics, Volume 75 Issue 10, 2012
DNA in nanochannels DNA confinement in nanochannels: physics and biological applications, Walter Reisner, Jonas N Pedersen and Robert H Austin, Reports on Progress in Physics, Volume 75 Issue 10, 2012
Length of DNA E. coli: a) 1.6 µm b) 1.6 mm c) 1.6 m http://english.globalgujaratnews.com/article/scientists-chance-upon-protein-that-can-kill-e-coli/ DNA confinement in nanochannels: physics and biological applications, Walter Reisner, Jonas N Pedersen and Robert H Austin, Reports on Progress in Physics, Volume 75 Issue 10, 2012
Length of DNA The human (diploid) genome: a) 2 cm b) 2 dm c) 2 m http://globalgenes.org/ten-years-of-human-genome/ DNA confinement in nanochannels: physics and biological applications, Walter Reisner, Jonas N Pedersen and Robert H Austin, Reports on Progress in Physics, Volume 75 Issue 10, 2012
Nanopores https://nanoporetech.com/how-it-works Nature Biotechnology 26, 1146-1153 (2008)
Organs on chip Improved In-vitro models, eg. for drug testing
How do you make microfluidic chips?
Cleanroom
Photolitography 1. Spin on photoresist 2. UV lithography 3. Develop photoresist 4. Bond glass lid Silicon (Si) Photoresist Borofloat glass
Silicone molding 1. Pour on PDMS 2. Cure 3. Peel off 4. Bond glass or PDMS lid Silicon (Si) Photoresist Borofloat glass PDMS silicone
Etching 1. Etch 2. Remove photoresist 3. Bond glass lid Silicon (Si) Photoresist Borofloat glass
Micromilling
3D-printing
3D laser photopolymerization
Summary Surface effects dominate over volume effects Laminar flow Miniaturization of existing methods New phenomena
Mer mikrofluidik: Introduktion till mikrofluidik och lab-on-a-chip-system (LP1) Lab-on-a-chip i biomedicinska tillämpningar (LP4) Exjobb bme.lth.se
Questions