“Overpass” at the junction of a crossed microchannel: An enabler for 3D microfluidic chips

Abstract

Reported here is the design and fabrication of three-dimensional (3D) "overpass" microstructures at the junction of crossed microfluidic channels by femtosecond laser direct writing of photopolymers. The post-integrated overpass could be used for guiding different microfluids across the junction without mixing; therefore it is proposed as an enabler for achieving 3D microfluidic chips based on conventional two-dimensional (2D) microchannels. As representative examples, bi-crossed and tri-crossed microchannels have been equipped with bi-connected and tri-connected overpasses, respectively. Flow tests confirm 3D flowing capability. The integration of such overpass structures at the microchannel junction provides an opportunity to impart 3D capability to conventional 2D microchips, thus the method may hold great promise for both functionalization and miniaturization of Lab-on-a-Chip systems.

In-channel integration of designable microoptical devices using flat scaffold-supported femtosecond-laser microfabrication for coupling-free optofluidic cell counting

“…Microoptical components require high surface smoothness to guarantee their optical performance compared with other microcomponents. [16][17][18][19][20]30,31 Moreover, the flatness of the internal surfaces of the microchannels on which the components are created significantly affects their quality. Over areas measuring a few dozen microns on a side, the surfaces fabricated by FLAE have adequate optical quality.…”

“…This method has been used to integrate various 3D functional microdevices, [16][17][18][19][20] such as a microfilters, 16 mixers 18 or overpasses, 19 into a 2D microchannel for controllable filtering of particles, high-efficiency mixing of different solvents, and guiding of different fluids and cell migration, respectively. However, all these works concern the integration of mechanical devices or 3D models in microchannels.…”

Femtosecond laser three-dimensional micro- and nanofabrication

“…Therefore, TPP is generally used for integration of functional microcomponents into planar open microfluidic structures prepared using other techniques such as photolithography. Functional microfluidic systems that can perform controlled filtering of particles, high-efficiency mixing of different solvents, and individual guiding of different fluids have been successfully fabricated by the integration of TPPfabricated microfilters, 84 mixers, 69,85 and overpasses 86 into open microfluidic channels, respectively. A more detailed review of TPP applications for microfluidic device fabrication is available in Ref.…”

Femtosecond laser internal manufacturing of three-dimensional microstructure devices

“…Zhou et al [58] made a 3D channel structure through two-photon exposure of BSB-S 2 (2002); He et al [84] developed a method to build a 3D 'overpass' at the junction of crossed microchannels as a microchannel switch. Lindenmann et al [85] demonstrated a photonic chip-to-chip interconnection technique, named photonic wire bond (PWB), capable of linking nanophotonic SOI waveguides.…”