Processing of PMMA for microfluidic applications

Application note No. AN1012IL02
Experiments and image processing:
Joe Yu1), Paul Webster 1), Ben Leung 1), Kevin Mortimer1), Logan Wright1)

Report written by:
Joe Yu1) (edited by James Fraser1))

1)
Queen’s University
Material: PMMA
Application
DNA, amino acids, peptides and protein analysis, profiling saccharides, pollutants, nerve agents, and explosives screening, electrophoretic separation of ions, and detection of purines
Current methods of fabrication: hot embossing, room temperature imprinting, injection molding, laser ablation, in situ polymerization and solvent etching. Chen et al. [Eletrophoresis. Fabrication, modification, and application of poly(methyl methacrylate) microfluidic chips, 29: 1801-1814 (2008)] gives an overview of applications and fabrication techniques.
Specifically, Sun et at. [J. Micromech. Microeng. Low-pressure, high-temperature thermal bonding of polymeric microfluidic devices and their applications for electrophoretic separation, 16: 1681-1688 (2006)] use a CO2 laser with varying power and scan speeds. Showcased is a trench cut at 0.75 W average power and a scan speed of 32 mm/s giving a volumetric removal rate of 120 μm3/μsec. Feature size, heat affected zone and processing speed are all important considerations for the application.

Laser tested
Ekspla PL10100 (centre wavelength: 1064 nm, repetition rate: 50 kHz). Patterning done with galvo scanning.

EKSPLA note: due to the continuous product improvements, laser models were replaced respectively: NL640 and NL15100 were replaced by Baltic and BalticHP series, PL10100 was replaced by Atlantic series.

In situ imaging
White light interferometer centred at 800 nm (“OCT M mode”) with image line rates up to 312 kHz (axial image).
Ex situ imaging
Bright field microscopy.