MICROCLEAR – A NOVEL METHOD FOR DIODE LASER WELDING OFTRANSPARENT MICRO STRUCTURED POLYMER CHIPS

摘要

Laser welding is a well established method for bondingof polymers. However, reliable and fast bonding oftransparent micro structured polymer chips used as biochemical sensor disposables with transparent coverfoils show a lot of unsolved problems. On the one handthese originate from the filler particles necessary forthe welding process, which could cause fluorescencewhich is mostly undesirable for the bio-medicalapplications with optical detection. On the other hand,a large effort has to be made with conventionalwelding methods such as quasi-contour welding andmask welding techniques since a precise alignmentbetween mask and work piece or laser spot andmicrostructure, respectively, is required. Furthermore,they require expensive polymers with dye fillers.These problems could be overcome with the newlydeveloped Microclear technology. Thereby a masklesswelding technique using a laser-diode bar with aline focus in combination with a special absorber layertechnique is applied. In the cover foils a dye absorberinterface layer is generated by controlled in-diffusionof a laser radiation absorbing dye, into which the laserenergy is deposited. No additional carrier material isrequired for the generation of the absorber layer. Dueto the very local confinement of the laser energy in thethin interface region, thermal damage of the microstructuredsubstrate is avoided and the radiation itselfdoes not have to be confined to the contact zone ofboth weld partners. Experimentally the novelMicroclear technology is successfully demonstrated bywelding of multi-channel polymer chips used forelectrophoresis.