Femtosecond pulsed laser direct write production of nano- and microfluidic channels

Abstract

Nano-and microfluidic channels were produced by selectively delaminating 1200 nm thermally grown oxide films ͑SiO 2 ͒ films from Si͑100͒ substrates using a femtosecond pulsed laser. Single pass channels exhibiting bell-like cross sections with widths of 24 m and heights of 355 nm were directly written at a speed of 1 cm/ s, while larger channels ͑320 m in width and ϳ15 m in height͒ were produced by laterally overlapping single pass channels. The results of an investigation of the interior surfaces of the channels via atomic force microscopy and scanning electron microscopy are presented.

Quantized structuring of transparent films with femtosecond laser interference

“…This geometry for internal laser cleaving has not been previously reported inside a transparent material and greatly extends the control over the laser modification in contrast with internal structuring over the whole laser focal volume 6 or structuring confined at a film/substrate interface. 9,[25][26][27]32 Further, the predicted plasma disks were shown by intensified CCD imaging (Figure 3) to validate the quantized ejection of multiple segments in a temporal sequence. Both internal structuring and quantized ejection of films was observed in 500-1500 nm thick films with either uniform ( Supplementary Fig.…”

“…5,6 In a different approach, femtosecond laser light has been transmitted through a thin transparent film and confined to interact within the thin penetration depth of an underlying silicon substrate 7,8 on length scales much smaller than the depth of focus. This narrow interaction zone explodes between the thin film and bulk substrate to form thin-film blisters and nanofluidic networks at the interface 9 at low exposure, or the ejection of the whole film at high exposure. These ejection principles underlie the driving mechanisms in laserinduced forward transfer 10 for patterning dielectrics, 11 printing or additive manufacturing, 12 releasing layers, 13 matrix-assisted pulsed laser evaporation-direct write 14 and cell ejection by laser pressure catapulting.…”

Nanomorphing with Ultrafast Lasers and Biomedical Applications

“…Thus femtosecond laser machining rates would approach rates competitive with photolithographic techniques, while enabling nanoscale and three dimensional features to be formed outside of a clean room. This phenomenon also holds promise for industrial applications ranging from large arrays of nanowells to both in-plane and out-of-plane modification of patterned structures, performed entirely with a single optical machining device (McDonald, 2006). The high aspect ratio also relaxes the requirements for nanoscale calibration between the laser focus and a surface when holes are drilled, providing a useful way to fabricate the initial few microns of the pores that interface with the surface and a subsurface channel.…”

Interferometric femtosecond laser processing for nanostructuring inside thin film

“…Alternatively, focused ultrashort laser light has been used to selectively eject thin dielectric films from an underlying substrate driven by strong light-material interaction at the buried substrate-dielectric interface [13][14][15][16][17][18]. In this case, the short penetration depth of laser light in the underlying substrate confines the light-material interaction to a very narrow zone in comparison with the long depth of focus.…”