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An Extra Laser Welding Technique for Bonded Poly (methyl methacrylate) (PMMA) Chips to Avoid Edge Dehiscence
J-L. Wang and Z-F. Yin

Using a CO2 laser beam is an excellent technique for fabrication of microchannels with complicated shapes in most of polymer substrates; however, the bulges always occur along the microchannels and the substrate usually bends after CO2 laser ablation, which result in the dehiscence of the chip. In the present work, an extra welding method was developed for further increasing the bonding strength of poly (methyl methacrylate) (PMMA) microfluidic chips. The influence of the thickness of PMMA substrate on the stress distribution was investigated by numerical simulation based on the actual measurements of the deformation of PMMA bulges and substrate. Simulation results indicated that the deformed substrate with PMMA bulges will lead to the edge dehiscence of bonded PMMA chip. The study on the relationship between welding parameters on the bonding strength of the chip showed that the bonding strength can reach up to 1.54 MPa. Leakage tests also demonstrated the bonded PMMA chip can stand up to an air pressure of greater than 1.00 MPa.

Keywords: CO2 laser, poly (methyl methacrylate) (PMMA), polymer, microfluidic chip, microchannels, edge dehiscence, numerical simulation, Mooney-Rivlin model

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