Microchannels inside bulk PMMA generated by femtosecond laser using adaptive beam shaping

Area of Science:

• Materials Science
• Laser Physics
• Microfabrication

Background:

• Femtosecond laser processing is a key technique for fabricating microstructures in polymers.
• Achieving precise control over microchannel geometry, especially circularity and length, remains a challenge.
• Spherical aberration and input beam shape significantly impact laser-induced channel formation.

Purpose of the Study:

• To report the generation of internal microchannels with extended lengths in Polymethyl methacrylate (PMMA) using femtosecond laser.
• To investigate the influence of spherical aberration correction and input beam ellipticity on microchannel circularity.
• To demonstrate the applicability of this laser-based fabrication method for creating microfluidic devices.

Main Methods:

• Utilizing femtosecond laser pulses for material ablation and channel generation within PMMA.
• Employing a spatial light modulator to compensate for depth-dependent spherical aberration.
• Implementing adaptive optics to generate a rotatable elliptical input beam for optimized beam shaping.
• Analyzing the effect of input beam ellipticity and spherical aberration correction on the circularity of the generated microchannels.

Main Results:

• Successfully generated internal microchannels of virtually unlimited length within PMMA.
• Demonstrated precise control over the circularity of the microchannel cross-section by correcting spherical aberration.
• Showcased the impact of input beam ellipticity on the resulting channel geometry.
• Fabricated functional microfluidic testing structures within a transparent polymer using the developed technique.

Conclusions:

• Femtosecond laser processing, with advanced optical compensation techniques, allows for high-aspect-ratio microchannel fabrication in PMMA.
• The presented method offers precise control over microchannel geometry, crucial for advanced microfluidic applications.
• This technique provides a versatile platform for creating custom microfluidic devices and other complex microstructures in transparent polymers.