Microfluidic components 2016 sami.franssila@aalto.fi
Contents Pumping Valving Dosing/dispensing Centrifugal fluidics PCR CE Optofluidics flow control applications
Pumps bubble pumps membrane pumps diffuser pumps rotary pumps electrohydrodynamic electro-osmotic ultrasonic pumps vacuum pumps Only some of these scale beneficially into microscale !!
Membrane pumps: actuation
Pumps without moving parts Surface tension driven pump Electro-osmotic pump Nozzle-diffuser pump, Olsson, Stemme 1997
Osmotic pump
Passive Active valves mechanical pneumatic geometric thermopneumatic hydrophobic phase-change electrostatic piezoelectri thermal expansion
Membrane valve, pneumatic actuation PDMS as flexible membrane Air in actuation channel, Liquid in fluidic channel. Air pressure deflects thin membrane against the wall of fludic channel. Why is it important that the fluidic channel is hemispherical ?
PDMS valve actuation http://www.wormbook.org/chapters/www_microfluidics/microfluidics.html
How would this work ? http://web.stanford.edu/group/foundry/Chip_Bonding.html
Cell stretch chip Zhang & Jiang, Lab Chip 2012 p 3441
PDMS flap valve (1) 3-layer PDMS structure Thin central layer bends and opens and closes the valve.
PDMS flap valve (2) PMMA/PDMS valves and pumps for disposable microfluidics DOI: 10.1039/B907254C
Peristaltic pump = 3 valves in series
Geometric valves Pillar “forest” controls the rate of capillary flow. Rapid constriction of the flow channel will stop the flow. Side channel offers timing of flow. Transducers 2005, p. 1565
Dosing/dispensing: ink jet MEMS Handbook
Electrospray nozzles
Electrospray nozzles
Microfluidic probe Juncker Delamarche Nature Materials 2005
In-channel dispensers Nguyen p.
PCR DNA copy machine
Thermal cycling Gold nanorod-facilitated localized heating of droplets in microfluidic chips Zhiyong Li, Pan Wang, Limin Tong, and Lei Zhang: Optics Express 2013
µPCR = rapid thermal ramping
Exponential amplification
Microfluidic PCR Silicon version:
Microfluidic PCR (2) SU-8 version:
Continuous flow PCR 3 contact temperature blocks Flow rate has been fixed so that the sample remains the right time in each temperature zone.
Electrophoresis chip with electrochemical detection
CE chip fabrication: channels in silicon (2)
CE chip fabrication: electrodes on polycarbonate (3) Lift-off
CE chip fabrication: electrodes on polycarbonate (4) Lift-off
Bond Si and PC to complete fabrication Polycarbonate Si
Optofluidics in PDMS One photomask !!
Optoelectrofluidics in silicon 13 photomasks required !!