Journal: Lab on a Chip

Article Title: Direct laser writing-enabled 3D printing strategies for microfluidic applications

doi: 10.1039/d3lc00743j

Figure Lengend Snippet: Fundamental concepts and developments for “direct laser writing (DLW)”. (a) Theory of two-photon absorption. Dashed lines = behaviour of an atom; upward and downward arrows represent absorbed and emitted photons, respectively. (b) Conceptual illustration and experimental results from the first demonstration in the literature for fabricating a three-dimensional (3D) model by exposing a liquid photomaterial to UV light in a point-by-point, layer-by-layer manner. (c) Conceptual illustrations of two configurations of the “stereolithography apparatus (SLA)” for building 3D objects via point-by-point, layer-by-layer polymerization of a photomaterial. (d) Schematic of the optical system and experimental results from the first demonstration in the literature for fabricating 3D microstructures via two-photon polymerization (2PP). (e–i) Conceptual illustrations of a representative DLW manufacturing process to produce 3D “DLW” microstructures. (e) Uncured photomaterial atop a print substrate. (f) A pulsed infrared (IR) laser is scanned point by point and/or layer by layer to initiate 2PP in target locations. (g) Completion of the DLW printing process. (h) The print is immersed in a developing agent to remove any uncured photomaterial. (i) Completion of the development process results in final microstructures—still adhered to the print substrate—comprising cured (crosslinked) photomaterial.

Article Snippet: Specifically, the photomaterial's refractive index ( n ) must match the specifications for a particular DLW 3D printer ( e.g. , n ≈ 1.5 at 780 nm for Nanoscribe Photonic Professional systems) and—because the objective lens is fully immersed in the photomaterial ( )—it cannot contain any materials that could corrupt or degrade the lens ( e.g. , certain solvents, acids, or bases).

Techniques:

Journal: Lab on a Chip

Article Title: Direct laser writing-enabled 3D printing strategies for microfluidic applications

doi: 10.1039/d3lc00743j

Figure Lengend Snippet: Microfluidic systems fabricated by enclosing DLW-printed 3D microstructures. (a–c) Conceptual illustrations of a representative fabrication protocol. (a) Microstructures DLW-printed onto a planar ( i.e. , flat) substrate ( e.g. , glass). (b) Channel enclosure. (Left) Alignment of an unenclosed microchannel with integrated macro-to-micro fluidic interfaces ( e.g. , an unenclosed PDMS microchannel with inlet/outlet ports) to the microstructures; and then (right) enclosure of the microfluidic system ( e.g. , via PDMS-to-glass bonding). (c) Loading of fluid into the enclosed microfluidic channel comprising DLW-printed 3D microstructures. (d–f) Representative examples in the literature. (d) PDMS-on-glass microfluidic system containing an array of DLW-printed 3D microrotors. (e) DLW-printed microstructures enclosed in microfluidic channels via : (top) mechanical clamping, and (bottom) PDMS-to-glass oxygen plasma bonding. (f) Microfluidic tissue culture system with DLW-printed 3D microfluidic capillary grids enclosed by mechanical clamping. (Top) Conceptual illustrations. (Bottom) Fabrication results.

Article Snippet: Specifically, the photomaterial's refractive index ( n ) must match the specifications for a particular DLW 3D printer ( e.g. , n ≈ 1.5 at 780 nm for Nanoscribe Photonic Professional systems) and—because the objective lens is fully immersed in the photomaterial ( )—it cannot contain any materials that could corrupt or degrade the lens ( e.g. , certain solvents, acids, or bases).

Techniques: Clinical Proteomics

Journal: Lab on a Chip

Article Title: Direct laser writing-enabled 3D printing strategies for microfluidic applications

doi: 10.1039/d3lc00743j

Figure Lengend Snippet: Microfluidic systems fabricated by DLW-printing 3D microstructures inside of an unenclosed channel and then enclosing the channel with a planar substrate. (a–c) Conceptual illustrations of an example fabrication protocol. (a) DLW-printing of microstructures directly inside of an unenclosed microchannel ( e.g. , wet-etched glass). (b) Channel enclosure by sealing a planar substrate ( e.g. , a PDMS slab) with integrated macro-to-micro fluidic interfaces atop the microchannel's open surface. (c) Loading of fluid into the enclosed microfluidic channel comprising DLW-printed 3D microstructures. (d–f) Representative examples in the literature. (d and e) Micrographs of microfluidic structures, including (d) microfilters with arbitrary pore designs and (e) multidirectional crossing manifold micromixers, which were DLW-printed inside wet-etched glass microchannels and then sealed using flat PDMS slabs. (f) A 3D micromixer that was DLW-printed inside unenclosed SU-8 photoresist-on-Si microchips and then sealed using a flat PDMS slab.

Article Snippet: Specifically, the photomaterial's refractive index ( n ) must match the specifications for a particular DLW 3D printer ( e.g. , n ≈ 1.5 at 780 nm for Nanoscribe Photonic Professional systems) and—because the objective lens is fully immersed in the photomaterial ( )—it cannot contain any materials that could corrupt or degrade the lens ( e.g. , certain solvents, acids, or bases).

Techniques:

Journal: Lab on a Chip

Article Title: Direct laser writing-enabled 3D printing strategies for microfluidic applications

doi: 10.1039/d3lc00743j

Figure Lengend Snippet: Microfluidic systems fabricated by DLW-printing 3D microstructures directly inside (and fluidically sealed to the entire luminal surfaces) of enclosed microchannels—strategies referred to as “ in situ DLW ( is DLW)”. (a–d) Conceptual illustrations of an example fabrication protocol. (a) Enclosed microfluidic device with tapered (≥30–34°) microchannel sidewalls and integrated macro-to-micro fluidic interfaces. (b) Liquid-phase photomaterial loaded into the device. (c) Microdevice after is DLW of “DLW” microfluidic structures. (d) Loading of fluid through the complete microfluidic system ( i.e. , through the “DLW” microfluidic structures). (e–j) Representative examples in the literature. (e) A microfluidic spinneret is DLW-printed inside a PDMS-on-glass microfluidic system with sol–gel-coated microchannels. (f) A porous microfilter is DLW-printed inside a commercial borosilicate glass microchannel chip. (g) A micromixer with integrated filter structures is DLW-printed inside a glass microchip (produced by femtosecond laser-assisted wet etching). (h) Micrographs of (top) interweaving tubular microvessel structures, and (bottom) a microfluidic transistor (left) and fluidic barrier structure (right), which were all is DLW-printed inside microdevices composed of the thermoplastic material, cyclic olefin polymer (COP). (i) A microfluidic circuit comprising two sets of fluidic microgrippers and two distinct microfluidic transistors, which were all is DLW-printed inside of a COP–COP microdevice. (j) Micrographs (top) before, and (bottom) after is DLW-printing of microfluidic barrier structures inside of a COP–COP microdevice via a photografting approach (based on benzophenone (BP) surface modification).

Article Snippet: Specifically, the photomaterial's refractive index ( n ) must match the specifications for a particular DLW 3D printer ( e.g. , n ≈ 1.5 at 780 nm for Nanoscribe Photonic Professional systems) and—because the objective lens is fully immersed in the photomaterial ( )—it cannot contain any materials that could corrupt or degrade the lens ( e.g. , certain solvents, acids, or bases).

Techniques: In Situ, MicroChIP Assay, Produced, Polymer, Modification

Journal: Lab on a Chip

Article Title: Direct laser writing-enabled 3D printing strategies for microfluidic applications

doi: 10.1039/d3lc00743j

Figure Lengend Snippet: Conceptual illustrations of a representative “oil-immersion” configuration-based DLW manufacturing process to produce 3D “DLW” microstructures. (a) Uncured photomaterial atop a thin, optically transparent print substrate with immersion oil between the underside of the print substrate and the objective lens. (b) A pulsed IR laser is scanned through the immersion oil, print substrate, and then the photomaterial (including in some case, previously polymerized microstructures) to initiate 2PP in target locations. (c) Completion of the oil-immersion mode DLW printing process.

Article Snippet: Specifically, the photomaterial's refractive index ( n ) must match the specifications for a particular DLW 3D printer ( e.g. , n ≈ 1.5 at 780 nm for Nanoscribe Photonic Professional systems) and—because the objective lens is fully immersed in the photomaterial ( )—it cannot contain any materials that could corrupt or degrade the lens ( e.g. , certain solvents, acids, or bases).

Techniques:

Journal: Lab on a Chip

Article Title: Direct laser writing-enabled 3D printing strategies for microfluidic applications

doi: 10.1039/d3lc00743j

Figure Lengend Snippet: Microfluidic components fabricated by DLW-printing independent 3D microfluidic entities for subsequent manual fluidic interfacing. (a–c) Conceptual illustrations of an example fabrication protocol. (a) DLW-printing of an independent microfluidic entity and removal from the print substrate. (b) Manual interfacing of the DLW-printed microfluidic entity to a mesoscale fluidic capillary, followed by the application of a sealant/adhesive. (c) Loading of fluid into (and through) the complete microfluidic component. (d–h) Representative examples in the literature. (d) DLW-printed 3D cell scaffold manually interfaced with a fluidic channel. (e) DLW-printed nuclear magnetic resonance (NMR) microfluidic component manually interfaced with mesoscale fluidic capillaries with connections fluidically sealed using epoxy. (f) DLW-printed nozzle manually interfaced with (and glued to) a glass capillary for microdroplet generation. (g) DLW-printed microfluidic structure manually interfaced (without sealants/adhesives) with a capillary bundle for delivery and sampling of nanolitre volumes. (h) DLW-printed modular gas dynamic virtual nozzle (with integrated micromixers) manually interfaced with (and glued to) glass capillaries for serial femtosecond crystallography at X-ray free-electron lasers.

Article Snippet: Specifically, the photomaterial's refractive index ( n ) must match the specifications for a particular DLW 3D printer ( e.g. , n ≈ 1.5 at 780 nm for Nanoscribe Photonic Professional systems) and—because the objective lens is fully immersed in the photomaterial ( )—it cannot contain any materials that could corrupt or degrade the lens ( e.g. , certain solvents, acids, or bases).

Techniques: Adhesive, Nuclear Magnetic Resonance, Sampling

Journal: Lab on a Chip

Article Title: Direct laser writing-enabled 3D printing strategies for microfluidic applications

doi: 10.1039/d3lc00743j

Figure Lengend Snippet: Microfluidic components fabricated by DLW-printing 3D microfluidic structures directly atop (and fluidically sealed to) meso/macroscale fluidic couplers and systems—strategies referred to as “ ex situ DLW ( es DLW)”. (a–d) Conceptual illustrations of an example fabrication protocol. (a) Photomaterial deposited on the tip of a mesoscale fluidic capillary. (b and c) “DLW” microfluidic structures es DLW-printed atop the capillary (b) before, and (c) after development. (d) Loading of fluid through the complete microfluidic component ( i.e. , through and out of the “DLW” microfluidic structures). (e–i) Representative examples in the literature. (e and f) Micrographs of (e) micropiston-actuated microgrippers, and (f) pneumatically actuated bistable microgrippers, es DLW-printed onto glass capillaries for manipulating microspheres. (g) Microfluidic structures with arbitrary geometries es DLW-printed onto fused silica glass capillary tubes and loaded with fluid. (h) Hollow microneedle arrays es DLW-printed onto “Digital Light Processing (DLP)” 3D-printed capillaries for injecting fluid into excised mouse brains. (i) Hollow conical microneedles es DLW-printed atop a microfluidic chip with external ports (prepared by femtosecond irradiation, annealing, grinding, and polishing).

Article Snippet: Specifically, the photomaterial's refractive index ( n ) must match the specifications for a particular DLW 3D printer ( e.g. , n ≈ 1.5 at 780 nm for Nanoscribe Photonic Professional systems) and—because the objective lens is fully immersed in the photomaterial ( )—it cannot contain any materials that could corrupt or degrade the lens ( e.g. , certain solvents, acids, or bases).

Techniques: Ex Situ, Irradiation

Journal: Lab on a Chip

Article Title: Direct laser writing-enabled 3D printing strategies for microfluidic applications

doi: 10.1039/d3lc00743j

Figure Lengend Snippet: Conceptual illustrations of a representative “vat” configuration-based DLW manufacturing process to produce 3D “DLW” microstructures. (a) Uncured photomaterial inside a vat with a print substrate (in an inverted orientation) with its surface immersed in the photomaterial with an air objective lens positioned below the base of the vat. (b) A pulsed IR laser is scanned through the vat and then the photomaterial to initiate 2PP in target locations while the print substrate is raised up from the vat (layer by layer). (c) Completion of the vat DLW printing process.

Article Snippet: Specifically, the photomaterial's refractive index ( n ) must match the specifications for a particular DLW 3D printer ( e.g. , n ≈ 1.5 at 780 nm for Nanoscribe Photonic Professional systems) and—because the objective lens is fully immersed in the photomaterial ( )—it cannot contain any materials that could corrupt or degrade the lens ( e.g. , certain solvents, acids, or bases).

Techniques:

Journal: Lab on a Chip

Article Title: Direct laser writing-enabled 3D printing strategies for microfluidic applications

doi: 10.1039/d3lc00743j

Figure Lengend Snippet: Summary of key characteristics of primary DLW-based strategies for fabricating 3D microfluidic technologies. Green text = advantageous capabilities; red text = disadvantageous capabilities

Article Snippet: Specifically, the photomaterial's refractive index ( n ) must match the specifications for a particular DLW 3D printer ( e.g. , n ≈ 1.5 at 780 nm for Nanoscribe Photonic Professional systems) and—because the objective lens is fully immersed in the photomaterial ( )—it cannot contain any materials that could corrupt or degrade the lens ( e.g. , certain solvents, acids, or bases).

Techniques:

Journal: Journal of Clinical Medicine

Article Title: Accuracy Assessment of Molded, Patient-Specific Polymethylmethacrylate Craniofacial Implants Compared to Their 3D Printed Originals

doi: 10.3390/jcm9030832

Figure Lengend Snippet: Comparison of the 3D printed templates ( a , b , beige) with the patient-specific implants according to the n-point registration with five manually placed control points ( c , d , purple), and the superimposition ( e , f ). Left: cranial template and PSI; right: temporo-orbital template and PSI.

Article Snippet: Subsequently, the STL files of the virtually planned templates were imported into the slicing software of a 3D printer (MakerBot Print v. 4.5.0.1729, MakerBot Industries, Brooklyn, New York, NY, USA).

Techniques: Comparison, Control