Crack-free direct-writing on glass using a low-power UV laser in the manufacture of a microfluidic chip

Abstract

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.

Surface Micro-Structuring of Silica Glass by Laser-induced Backside Wet Etching

“…3). 71,72) When a tightly focused beam of the single-mode laser was incident on the silica glass without liquid in the air, well-defined etching pit with 10 mm in diameter, which was free of debris and microcracks around the area, was formed by such conventional ablation. 74) However, upon the irradiation of several laser shots accumulated at the same position to make a deep pit structure on the surface, cracks were randomly formed around etched area, indicating that single-shot irradiation was a key for this well-defined micro-fabrication at the conventional ablation condition.…”

Effects of shear stresses and antioxidant concentrations on the production of reactive oxygen species in lung cancer cells

“…The pattern was drawn in AutoCAD (Autodesk) and then loaded into a CO 2 laser scriber (M-300, Universal Laser Systems or ILS2, Laser Tools & Technics Corp.) to ablate desired patterns on PMMA substrates. [53][54][55] Three layers ( Fig. 1(a), thickness ¼ 1 mm) were bound together via double-sided tapes (8018, 3M) to form the integrated chip ( Fig.…”

Photomasks Fabrication Based on Optical Reduction for Microfluidic Applications

“…Many maskless photolithography approaches, typically based on UV laser direct writing coupled by motorized stages [5][6][7][8], have been proposed, but since the mask approach results the most simple and practical method, innovative ideas have been suggested. Qin et al [9] described how image setting system can be useful to generate mask with feature sizes larger than 20 µm.…”