Laser-treated glass platform for rapid wicking-driven transport and particle separation in bio microfluidics

In this work, we present a laser-based fabrication technique for direct patterning of micro-channels consisting of interconnected micro-cracks on soda-lime glass. Using a CO₂ laser to deposit energy at a linear rate of 18.75 to 93.75 mJ mm^-1, we were able to manipulate the micro-crack formation, while enabling rapid manufacturing and scalable production of cracked-glass microfluidic patterns on glass. At the higher end of the energy deposition rate (93.75 mJ mm^-1), the laser fabricated microfluidic channels (1 mm wide and 20 mm long) had extremely fast wicking speeds (24.2 mm s^-1, ×10 faster than filter paper) as a result of significant capillary action and laser-induced surface hydrophilization. At the lower end (18.75 mJ mm^-1), 3-4 μm wide micro-cracked crevices resulted in an increased mesh/sieve density, hence, more efficiently filtering particle-laden liquid samples. The reproducibility tests revealed an averaged wicking speed of 10.6 ± 1.5 mm s^-1 measured over 21 samples fabricated under similar conditions, similar to that of filter paper (∼85%). The micro-cracked channels exhibited a stable shelf life of at least 82 days with a wicking speed within 10-13 mm s^-1.