No abstract

The authors demonstrate that optical gratings with 600 and 1500nm periods on a Pd40Ni40P20 bulk metallic glass (BMG) can be faithfully imprinted in air from Si dies. Results of scanning electron microscopy, atomic force microscopy, and optical diffraction analysis show the fine line feature of ∼150nm. The gratings have smooth and uniform surface profiles with comparable optical properties as the original Si dies. The BMG gratings can be further used to imprint the second-generation replicas on polymethylmethacrylate. Thereby, BMG is a suitable material not only for imprinting nanostructured parts such as gratings, but also as a good die material for nanoimprints.

Glass is an excellent material for use as a microfluidic chip substrate because it has great chemical and thermal stability. This work describes a flexible platform for the rapid prototyping of microfluidic chips fabricated from glass. A debris-free laser direct-writing technology that requires no photomask generation is developed. A 266 nm laser with a high repetition rate is employed in laser-induced backside wet etching (LIBWE) for glass machining. A microfluidic pattern is designed using computer drawing software and then automatically translated into computer numerical control motion so that the microtrench is directly fabricated on the glass chip. The overall machining speed can be increased by increasing the repetition rate to ∼6 kHz. Without a clean room facility or the highly corrosive acid, HF, the overall development time is within hours. Trenches with complex structures that are hard to fabricate by photolithography were easily produced by laser direct-writing. An integrated microreactor/concentrator is demonstrated. The crack-free and debris-free surface was characterized by SEM and a surface profiler. Various effective etching chemicals for the LIBWE process were investigated to understand the etching mechanism. The minimal laser power used for glass etching was approximately 20 mW for a 6 µm wide microtrench. Several new compounds have been demonstrated to be effective in ablation. The etch threshold is minimum and does not decrease further as the unit length absorbance increases above 8000 in acetone solution.