Udvikling, simulering og fabrikation
af mikroflowsystemer
Ulrich Krühne, PhD.
Center for Mikroteknologi og Overfladeanalyse
Små, mindre og mikroflow – og de særlige udfordringer
Seminar, Force Technology 17. marts 2010
Indhold
•Teknologisk Institut
•Fabrikation
•Simulering
•Praktiske problemer
•Cases
Danish Technological Institute
Brief description:
• Not-for-profit organisation approved by the Danish government
• Funded in 1906
• Employs ca.1000 people mainly scientist, engineers and technicians
• Turnover: 842 million DKK (2009)
• ca. 40 centres organised in eight divisions:
− Building technology
− Industry and Energy
− Informatics
− Materials (Centre for Microtechnology and Surface Analysis)
− Productivity and Logistics
− Industrial development
− Life Science
− Conferences and courses
Mission: to bridge the gap between science and industrial
application of new technologies
Om Instituttet
Technologies and know-how:
• Micro fluidic systems
− flow simulations, prototyping, 3D design, system integration, µ-dispensing
•Surface characterisation equipment for structural and chemical analysis
− SEM, FIB-SEM, EDX, TOF-SIMS, AFM
• Lasers for physical changes of surface structures
− CO2-, excimer- , femto second-, and diode lasers
• Sensor technology
− Wireless readout platform
• Surface treatment and deposition equipment
− MVD, PE-CVD, (ALD)
•Clean room alliance with Danchip at DTU Nanotech
− Nanoimprinting and more
Centre for Microtechnology and Surface Analysis
Om Instituttet
Centre for Microtechnology and Surface Analysis
Our aim is:
• to provide the industry with new processes based on nano- and
microtechnology suitable for low cost mass production.
• use our knowledge base to tailor surface properties to customer needs
• help customers to identify where enhanced surface properties adds
endproduct value
Om Instituttet
Fabrikation
•Laser ablation
• (CO2, Excimer, Femtosecond)
•Laser bonding (diode laser)
•Microdispensing
•Micromilling
•Cleanroom process (Nanoimprint….)
•CFD simulation services
•MVD microfactory
•Robot assisted dispensing/bonding
•Microfluidic test platform
•Experience in micro-fluidic cell handling
•Experience in immuno-assays
•Experience in DNA hybridisation
•Fabrication of optical microstructures
•Micro-magnetic separation in MFS
Fabrikation eksempler
Fabrikation
Fabrikation eksempler
PET
PEEK
Replica
SU8
Excimer Laser
PET PTFE
Steel Steel
Teflon
Glass
Eksempler fs laser
Non Newtonian Fluids
Multiple Phase Flows
Surface reactions and multi-component flows
Evaporation
Coupling of velocity fields and magnetic fields and heat transfer
Computational Fluid Dynamics – The principle
Simulering
Can we trust the results?
Or the hard way of learning….
Das Autobone Projekt Contract No. 505711-1
Medical technology - Tissue Engineering
Materials technology on micro- and nano-level
Stem cell Bioreactor
Activation of scaffold surfaces,
through impregnation with active
substances/plasma activation, in
order to achieve specific cell
adhesion
Production unit for the decentralised engineering of autologous cell
based osteoinductive bone substitutes: AUTOBONE
A real scaffoldNaseem Theilgaard, Medical Devices, at the Danish
Technological Institute
Number of pores = 34
Total area = 23595 pixel
Pore area = 12305 pixel
Relative Pore Area = 0.5215Number of pores = 12
Total area = 14410 pixel
Pore area = 9407 pixel
Relative Pore Area = 0.6525Number of pores = 5
Total area = 2940 pixel
Pore area = 487 pixel
Relative Pore Area = 0.1656
FSI in Detail
Biological fluid structure interaction model
BMr
SO
BMd
rSrO
SO
Xr
KK
Xk
YY
YY BM
S
S
2O2
O2max
2
2
SO2BM
Xfwfactor ratestrain FactorC
C
C
C 1
1
nrespiratio eMaintenanc
Growth
Decay
______________________________________________________________________________________
vectorRate C C X Process
Parameter Value Units
µmax 3 kg m-3 s-1
Arbitrary wall function fw = 1 for XW >=1.10-5
fw = 0 for XW <1.10-5
1
Decay rate kd = 0.1 kg m-3 s-1
Factor 0 for XBM ≥ 0.95
1 for XBM < 0.95
1
1
Oxygen respiration rate for
maintenance
YrO2 = 1 kg m-3 s-1
Oxygen saturation
concentration
KO2 = 0.05 1
Respiration rate rr = 1 kg m-3 s-1
Stoichiometric coefficient for
oxygen throughout growth
YO2 =1 1
Stoichiometric coefficient for
substrate throughout growth
YS = 1 1
strain rate factor Shear Strain Rate < 218 → SSF = 0,00459 [s].SSRShear Strain Rate > 218 →SSF = -0,00459 [s].SSR+2
1
1
Substrate respiration rate for
maintenance
YrS = 1 kg m-3 s-1
Substrate saturation
concentration
KS = 0.05 1
νapp 5.10-3 1 XBM ≥ 0.95
1.10-3 1 XBM < 0.95
kg m-1 s-1
kg m-1 s-1
Component Symbol Units
Arbitrary wall
concentration
XW 1
Biomass
concentration level
XBM 1
Oxygen
concentration Level
CO2 1
Substrate
concentration level
CS 1
Table 3. Components of the biological model
Table 1. Biological model
Table 2. Model Parameters
Shear or no shear?
Evolutionary strategy for implant optimisation
Fact: Biological experiments have shown that cell grow better due to perfusion
Assumption: We know the optimal shear stress level and the model is sufficient
Geometry
Definition of Geometry - definition of boundary conditions – simulation – post processing –
calculation of cost function
Fluid – Solid Interaction Study
calculation of cost function Σ
Stochastic variation of geometry
Definition of boundary conditions – simulation – post processing – calculation of cost
function
calculation of new cost function Σnew
Σnew < Σtrue false
Keep geometry
n n
Transient changes of the geometry
Praktiske Problemer
Bubbles, the friend of
every person dealing with
microfluidics
Praktiske Problemer
Sometimes you can even
use them for something
Like e.g. ink/laser-jet printers
Sample separation
Praktiske Problemer: Bobbler
Whre do we see them?
•Pumps
•Flow splitter
•Injection ports
•Temperature changes
•Different surface energies in surfaces
•Too hydrophilic systems
e.g. syringes
Gas solubility = function
Of temperature
Fill hydrophob
2nd fill
Praktiske Problemer: Bobbler
How to get rid of them?
•Good Priming (high speed)
•Surface tension reduction (Tween 20/50 soap)
•Dissolve them
•Pressure changes
•Good surface characteristics
•If you have bubbles and cells the bubbles function as lawn-mower…
Cases
Cases Mikrodsipensering
Left 2,5 µL evaporation of
Na-Fl stained water
Right 60 pico litre evaporation of
Na-Fl stained water
Intensity profiles of the figures
125 µm125 µm
Contact
Ulrich Krühne
Teamleder Microfluidics
Gregersensvej 6H, 2630 Taastrup
+45 7220 3302
http://www.teknologisk.dk/specialister/22769