Femtosecond laser micromachining of dielectric materials for biomedical applications

Abstract

Techniques for microfluidic channel fabrication in soda-lime glass and fused quartz using femtosecond laser ablation and ablation in conjunction with polymer coating for surface roughness improvement were tested. Systematic experiments were done to characterize how process variables (laser fluence, scanning speed and focus spot overlap, and material properties) affect the machining feature size and quality. Laser fluence and focus spot overlap showed the strongest influence on channel depth and roughness. At high fluence, the surface roughness was measured to be between 395 nm and 731 nm RMS. At low fluence, roughness decreased to 100 nm-350 nm RMS and showed a greater dependence on overlap. The surface roughness of laser ablation was also dependent on the material properties. For the same laser ablation parameters, soda-lime glass surfaces were smoother than fused quartz. For some applications, especially those using quartz, smoother channels are desired. A hydroxyethyl methacrylate (HEMA) polymer coating was applied and the roughness of the coated channels was improved to 10-50 nm RMS.

Time integrated transient reflectivity versus ablation characteristics of Borofloat, BK7, and B270 optical glasses ablated by 34 fs pulses

“…The variance in the response of different target materials to irradiation with ultrashort pulses was examined as well [16,[36][37][38]. Single pulse ablation characteristics of silica have been reported [16,30,[33][34][35]37,[39][40][41][42][43][44][45]. CaF 2 [46], sapphire [16,40,47], various types of glasses [38,41,42,[48][49][50][51] and even polymers, e.g.…”

Multiscale Topological Guidance for Cell Alignment via Direct Laser Writing on Biodegradable Polymer

“…26 Recent application of femtolaser is in microfabrication of micro-electro-mechanical systems (MEMS) devices based on polymer, glass, 27 silicon wafer, 28 and dielectric materials such as soda-lime glass and fused quartz. 29 In tissue engineering application, femtosecond laser was reported in generating surface modification on polymer thin films such as poly(glycolic acid), 30 polypropylene, 31 and poly(ecaprolactone). 30,32 Creating microchannels directly on a biodegradable polymer scaffold using femtosecond laser has not been reported till date.…”

Flat fibre and femtosecond laser technology as a novel photonic integration platform for optofluidic based biosensing devices and lab-on-chip applications: Current results and future perspectives

“…The inscription procedure can therefore lead to markedly different results, and methods can be employed to improve or control roughness, such as overwriting existing channels, optimise the laser inscription energy and write velocity, in addition to control of the height of the laser focus point relative to the sample surface. Furthermore, these levels of average roughness can be significantly improved by post processing the samples, for example, coating the channels with hydroxyethyl methacrylate (HEMA) polymer coating that can lead to coated channels with an rms roughness of 10-50 nm [13]. Methods that introduce glass reflow in the femtosecond laser processed areas of the samples can also be used to improve levels of roughness, such as the use of optical polishing with CO 2 lasers or processing in a high temperature oven [14,15].…”