Glass etching to bridge micro- and nanofluidics

Area of Science:

• Materials Science and Engineering
• Microfluidics and Nanofluidics
• Fabrication Techniques

Background:

• Current fabrication methods for micro- and nanostructures can be complex and costly.
• There is a need for versatile and scalable techniques to produce structures with tunable dimensions.
• Controlling feature size at the nanoscale is crucial for advanced applications in microfluidics and sensing.

Purpose of the Study:

• To propose a simple, economical, and flexible fabrication technique for micro- and nanostructures.
• To demonstrate the transformation of microscale glass ridges into nanoscale features.
• To fabricate repeatable and mechanically stable polydimethylsiloxane (PDMS) micro/nanostructures.

Main Methods:

• Fabrication of glass molds with micro-nanostructures using glass microlithography.
• Controlled glass etching (specifically undercutting) to transform micro-ridges to nanoscale dimensions via isotropic etching and chromium shielding.
• Utilizing glass structure mold-copying to replicate structures in polydimethylsiloxane (PDMS).
• Characterization using Scanning Electron Microscopy (SEM) and Laser Interferometry (LI).

Main Results:

• Successfully transformed microscale glass ridges into nanoscale structures with triangular cross-sections.
• Achieved precise control over nanoscale dimensions by leveraging edge effects during the late etching stage.
• Fabricated well-repeatable, mechanically stable, and tunable PDMS channels and cones.
• Demonstrated the utility of the fabricated structures for sample preconcentration down to the single nanochannel level.

Conclusions:

• The proposed glass microlithography and etching technique offers a simple and economical route to micro- and nanostructures.
• The method provides flexibility in design and precise control over feature size, enabling tunable PDMS devices.
• The fabricated micro/nanostructures are suitable for advanced applications, including highly sensitive preconcentration in nanochannels.