Abstract
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.
Highlights
At the lower end (18.75 mJ mmÀ1), 3–4 mm wide micro-cracked crevices resulted in an increased mesh/sieve density, more efficiently filtering particle-laden liquid samples
The reproducibility tests revealed an averaged wicking speed of 10.6 Æ 1.5 mm sÀ1 measured over 21 samples fabricated under similar conditions, similar to that of filter paper ($85%)
Together, wicking and particle separation are two principal necessities for many micro uidics and lab-on-a-chip applications, but they o en require multiple distinct materials which are difficult to integrate with established microfabrication techniques and materials
Summary
Due to its optical transparency, rigidity, bio-compatibility, and ease of surface modi cation/functionalization, glass has traditionally been one of the workhorse materials in the fabrication of micro uidic and other biomedical lab-on-a-chip devices.[1,2,3] Recently, researchers have investigated lower-cost, exible substrates such as functionalized polymers[2,4,5] and paper,[6,7,8] whose remarkable inherent wicking properties and ltration capabilities have allowed the realization of a variety of passive analytical microsystem.[8,9,10] Wicking, in particular, offers the advantage of passive liquid transport[11,12] without the need for a micro-pump, signi cantly reducing the system complexity and cost. At the higher end of the energy deposition rate (93.75 mJ mmÀ1), the laser fabricated microfluidic channels (1 mm wide and 20 mm long) had extremely fast wicking speeds (24.2 mm sÀ1, Â10 faster than filter paper) as a result of significant capillary action and laser-induced surface hydrophilization.
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