Optimization of selective laser etching (SLE) for glass micromechanical structure fabrication

Abstract

In this work, we show how femtosecond (fs) laser-based selective glass etching (SLE) can be used to expand capabilities in fabricating 3D structures out of a single piece of glass. First, an investigation of the etching process is performed, taking into account various laser parameters and scanning strategies. These results provide critical insights into the optimization of the process allowing to increase manufacturing throughput. Afterward, various complex 3D glass structures such as microfluidic elements embedded inside the volume of glass or channel systems with integrated functional elements are produced. A single helix spring of 1 mm diameter is also made, showing the possibility to compress it by 50%. Finally, 3D structuring capabilities are used to produce an assembly-free movable ball-joint-based chain and magnet-actuated Geneva mechanism. Due to minimized friction caused by low (down to 200 nm RMS) surface roughness of SLE-produced structures, the Geneva mechanism was shown to be capable of rotating up to 2000 RPM.

Peculiarities of Integrating Mechanical Valves in Microfluidic Channels Using Direct Laser Writing

“…Another option would be to use glass micromechanics, produced by fs selective glass etching (SLE). These were shown to also provide assemblyfree capabilities of fabrication, somewhat similar to MPP, yet more sensitive to manufacturing parameters [32]. Additionally, multistep 3D additive manufacturing can also be employed in a similar fashion [33][34][35].…”

Microfluidic quantum sensing platform for lab-on-a-chip applications

“…giving rise to high selectivity and, thus, high spatial resolution (∼ 1 µm in XY and ∼ 2 µm in the Zdirection, [34]). The main advantage is that 3D internal channels can be fabricated as long as the total distance to the next opening is ∼ 10 mm [33] to ensure sufficient exchange of etching medium.…”

“…The modified glass is subsequently wet-etched with either potassium hydroxide or hydrogen fluoride solution (see Fig. 2c) with significantly increased etching rates compared to non-illuminated sections, thus, exposing the negative 3D image [33,34]. The etch-rate increase of the laser-modified material can be more than 1,400:1 in quartz silica [33],…”

Microfluidic quantum sensing platform for lab-on-a-chip applications

“…We employ selective laser etching (SLE) to produce the microfluidic platform from quartz glass, i.e., synthetic fused silica [36,37] 2b) [38]. Three-dimensional spatial selectivity is achieved due to the highly nonlinear nature of the light-matter interaction in the focal volume [38].…”