Title: Morphology and geometry of CO2-laser machined PMMA microchannels: influence of molecular weight and number of cut passes

Authors: C.Y. Yue, Y.C. Lam, Nimai C. Nayak

Addresses: Singapore-MIT Alliance, Manufacturing Systems and Technology Programme, Nanyang Technological University, 65 Nanyang Drive, 637460, Singapore; School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore. ' Singapore-MIT Alliance, Manufacturing Systems and Technology Programme, Nanyang Technological University, 65 Nanyang Drive, 637460, Singapore; School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore. ' Singapore-MIT Alliance, Manufacturing Systems and Technology Programme, Nanyang Technological University, 65 Nanyang Drive, 637460, Singapore

Abstract: Laser micromachining has been utilised for fabricating channels in polymeric microfluidic devices. The present work focuses on a study of the influence of polymer molecular weight (Mw) on the depth and width of microchannels in polymethyl methacrylate (PMMA) that are machined using a CO2 laser. PMMA of four molecular weights, namely, 96.7 kDa, 120 kDa, 350 kDa and 996 kDa were used. The laser cut was performed at low power ratings of between 0.25 W to 2.5 W and the cutting speeds ranged from 7.0 to 64 mm/s. The depth and width of the machined microchannels varied from 18 μm to 660 μm and 110 μm to 450 μm respectively. The effect of the number of cut passes during laser micromachining on the morphology of the microchannel was considered by subjecting each microchannel up to 7 cut passes. It was demonstrated that microchannels with smooth surfaces could be obtained using CO2 laser machining and that the conditions for obtaining the smooth microchannels depend on the polymer molecular weight.

Keywords: laser ablation; polymethyl methacrylate; PMMA; molecular weight; channel depth; channel width; surface morphology; cut passes; laser machining; microchannels; micromachining; polymeric microfluidic devices; microfluidics.

DOI: 10.1504/IJNM.2010.034775

International Journal of Nanomanufacturing, 2010 Vol.6 No.1/2/3/4, pp.85 - 98

Published online: 22 Aug 2010 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article