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Surface characterization of laser-ablated polymers used for microfluidics
D L Pugmire1, E A Waddell, R Haasch
1National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA. pugmire@nist.gov
Analytical Chemistry
|February 28, 2002
Summary
Laser ablation of polymers like PETG, PVC, and polycarbonate under oxygen creates microchannels with high electroosmotic (EO) mobility. Ablation under nitrogen or argon results in low EO mobility and altered surface chemistry.
Area of Science:
- Polymer science
- Surface chemistry
- Microfluidics
Background:
- Excimer laser ablation is used to fabricate microfluidic devices.
- Atmosphere during ablation can influence polymer surface characteristics.
Purpose of the Study:
- To investigate how different ablation atmospheres affect polymer microchannel surface chemistry and electroosmotic (EO) mobility.
- To determine optimal conditions for fabricating microfluidic devices with desired surface properties.
Main Methods:
- Polymer samples (PMMA, PETG, PVC, polycarbonate) were ablated using excimer laser.
- Surface chemistry was analyzed using X-ray photoelectron spectroscopy (XPS).
- Electroosmotic mobility was measured using current monitoring.
Main Results:
- PMMA showed minimal surface changes due to low light absorption.
- PETG, PVC, and polycarbonate exhibited significant surface chemistry and EO mobility changes.
- Ablation under nitrogen or argon led to low EO mobility and loss of native chemical structures.
- Ablation under oxygen resulted in retained native structures and higher EO mobilities.
Conclusions:
- Ablation atmosphere critically impacts surface chemistry and EO mobility of specific polymers.
- Oxygen atmosphere is preferable for fabricating microfluidic channels with high EO mobility.
- Laser ablation parameters, including atmosphere, must be carefully controlled for microfluidic device fabrication.