SU-8 Polymer in Microfluidics - Micronovamicronova.tkk.fi/files/Micronova Seminar 2005/SU-8... ·...

Santeri Tuomikoski, 9. 12. 2005

SU-8 Polymer in Microfluidics

Santeri TuomikoskiMicroelectronics CentreMicrofabrication group

Helsinki University of Technology


MicrofluidicsDevelopment towards integrated systems

Micro total analysis systems, µ-TASLab on a chip – concept

Smaller dimensions => large area/volumeImproved reactions, separations and detections

Faster and more sensitive separations or reactionsPrice should be minimized

Cheap fabricationConsumption of chemicals and analytes

Possible material selection is wide


Polymer microfabricationPossible techniques

Replication of structures to polymer• Hot embossing, Injection molding, Casting…

Direct fabrication methods for polymers• Lithography, Laser ablation…


LithographyRelatively easy fabricationModerate price of fabricationLarge freedom for fabrication

Other processing equipment are usable

Lithography good for research of microfluidicsSelection of materials

Lot of different materialsLimited amount suitable for structural material


Epoxy photoresist SU-8Patterning with UV-lightSU-8 enables good processing capabilities

Lot of research done with the material in MEMSChannels and other structures can be accurately patterned

Problem with enclosure of the channels

Various methods are published, but have limitations

SU-8 properties for microfluidics are not well known

CH3C

O

CH2

CHH2C O

O

CH2

CHCH2

O

CH3

CH2

CH3C

O

CH2

CHH2C O

O

CH2

CHCH2

O

CH3

CH2

CH3C

O

CH2

CHH2C O

O

CH2

CHCH2

O

CH3

CH2

CH3C

O

CH2

CHH2C O

O

CH2

CHCH2

O

CH3


Microchannels from SU-8Channel formation with lithographyEnclosure with adhesive bondingFree-standing channelsHigh yield of channelsUniform shape of channelsEasy inlet fabrication

Santeri Tuomikoski, Sami Franssila, Free standing microfluidic chips by adhesivebonding and release etching, Sens. Actuators A, 120, (2005), 408-415

Santeri Tuomikoski, Sami Franssila, Wafer-level bonding of MEMS structures with SU-8 epoxy photoresist, Physica Scripta, T114, (2004) 223-226


SU-8 channels


Microfluidics with SU-8Separation

ElectrophoresisSolid phase extraction - electrophoresis

Detection methodsOptical detection

• Fluorescence• Laser induced fluorescence (LIF)

Electrical conductivity detectionMass spectrometry

• Coupling microchip with mass spectrometer


Electrophoresis

Heiger, D., An introduction High performance capillary Electrophoresis, Agilent Technologies, 2000


EOF-characterization

Sikanen, T., Tuomikoski, S., Ketola, R., Kostiainen, R., Franssila S., Kotiaho, T., Characterization of SU-8 for electrokinetic microfluidic applications, Lab on Chip, 5, (2005), 888-896.


Integrated SPE-ZE chipElectrophoresis channel integrated with SPESample concentrationSample purificationSelective extraction

Tuomikoski, S., Virkkala, N., Rovio, S., Hokkanen, A., Siren, H., Franssila, S., Design and fabrication of integrated sold phase extraction – zone electrophoresis microchip, J. Chromatogr A. Accepted for publication.


SPE-ZE


SPE-ZELaser induced fluorescence detectionBeam is split => detection of two spots simultaneouslyPossible to detect separation and SPE

Argon Laser488 nmCCD

camera

XYZ-table

Lens, f=100 mm

Mirror

Lens, f=50 mm

Bandpass filter488+/- 5 nm

Bandpass filters520+/- 5 nm

Chip

Fluidics andelectricalconnections

Beam splitter

Attenuation filters

0500

10001500200025003000350040004500

0 50 100 150 200

Time (sec)

Fluo

resc

ence


Microchips with mass spectrometer

Huikko, K., Östman, P., Grigoras, K., Tuomikoski, S., Tiainen, V.-M., Soininen, A., Puolanne K., Manz, A., Franssila S., Kostiainen R., Kotiaho, T., Lab on chip, 3, (2003), 2, 67-72.

Tuomikoski, S., Huikko, K., Grigoras, K., Östman, P., Kostiainen, R., Baumann, M., Abian, J., Kotiaho, T., Franssila, S., Lab on chip, 2, (2002), 4, 247-253.

Östman, P.; Marttila, S. J.; Kotiaho, T.; Franssila, S.; Kostiainen, R.; Anal. Chem. ; 2004; 76 (22); 6659-6664.

Kauppila, T. J.; Östman, P.; Marttila, S.; Ketola, R. A.; Kotiaho, T.; Franssila, S.; Kostiainen, R.; Anal. Chem., 2004; 76 (22); 6797-6801.


Electrospray ionization MS


SU-8 ESI-chips

Tuomikoski, S., Sikanen, T., Ketola, R., Kostiainen, R., Kotiaho, T., Franssila S., Fabrication of enclosed SU-8 tips for electrospray ionization mass spectrometry, Electrophoresis, Accepted for publication.


SU-8 ESI-chips


Taylor cone with SU-8 tipsWell defined Taylor coneNo liquid spreading at the tipUniform electrospray


Results with SU-8 ESI

An averaged (60 scans) mass spectra (a) and total and verapamil ion currents (b) of 5 µM verapamil in methanol-water (80/20, v/v) with 5 mM ammonium acetate. The measurements were carried out with electroosmotic flow alone with microchannel diameter of 100 µm × 50 µm and with spraying voltage of +2,5 kV

0,0E+00

1,0E+06

2,0E+06

3,0E+06

4,0E+06

5,0E+06

6,0E+06

100 150 200 250 300 350 400 450 500

m/z, amu

Inte

nsity

, cps

[M+H]+=455.4

214.3

1,0E+00

1,0E+01

1,0E+02

1,0E+03

1,0E+04

1,0E+05

1,0E+06

1,0E+07

1,0E+08

1,0E+09

0 1 2 3 4 5 6 7 8

Time, min

Inte

nsity

, cps

Total ion current (100-500 amu), RSD 3,53 %

Verapamil ion current (455.4 amu), RSD 6,71 %


Results with SU-8 ESI

0,0E+00

5,0E+05

1,0E+06

1,5E+06

2,0E+06

2,5E+06

3,0E+06

550 650 750 850 950 1050 1150 1250 1350m/z, amu

inte

nsity

, cps+20 +18

+22+21 +17

+15

+14

+13

+23

+24

+25

+16

+19

+26

SU-8 tip with horse heart myoglobin sample. A summed mass spectrum (10 scans) is measured with pressure driven flow of 750 nl/min. Applied voltage was +2.5 kV. Sample solution contained 0.1 mg/ml horse heart myoglobin in 1:1 acetonitrile:water solution with 0,1 % of formic acid.


Electrode integration for SU-8


ConclusionsSU-8 is good material for microfluidics

Solvent compatibilityUniformly charged wallGood detection possibilitiesNo noticed interaction of SU-8 and analytes

Successful fabrication of enclosed channelLong channelsLarge scale for width and heightBonding of large areas and small pillarsEasily integrated systems


AcknowledgementsVTT

Stella RovioHeli SirénAri HokkanenTarja Nevanen

Funding:TEKES Academy of Finland

HUT/MECSami FranssilaTero RistolainenNina Virkkala

UH/Analytical chemistryTiina SikanenTapio Kotiaho

UH/Faculty of PharmacyIiro KorpisaloRaimo KetolaRisto Kostiainen

Thank you for your attention

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