PDMS microfluidic devices bonded to a glass substrate were formed via conventional soft lithography using SU8-2025 Photoresist (MicroChem Corp.) masters on 3″ silicon wafers (WRS Materials).34 Photomasks were designed in AutoCAD (Autodesk) and printed as transparencies (CAD/Art Services). Prior to use, masters were treated with (tridecafluoro-1,1,2,2-tetrahydrooctyl)tri-chlorosilane (Gelest, Inc.) under vacuum for 2–4 hours. PDMS was mixed 10:1 (RTV615A:RTV615B) (Momentive) and cured for 1 hour at 70 °C. PDMS molds were removed from the master and punched with 20 Ga needles to create ports. PDMS molds and glass slides (Cover Glass, Thickness 1½, 22 × 40 mm, Corning, Inc.) were bonded following oxygen plasma activation (PDC-32G, Harrick Plasma). Devices were incubated at 70 °C overnight and treated with 1% (tridecafluoro-1,1,2,2-tetrahydrooctyl)trichlorosilane in FC-40 (Sigma Aldrich). All channels were 40 μm in height.
Su 8 2025 photoresist
Manufactured by MicroChem
Sourced in United States
SU-8 2025 is a high-contrast, epoxy-based photoresist designed for microfabrication applications. It is a negative-tone resist that undergoes cross-linking upon exposure to ultraviolet (UV) light, resulting in exposed areas becoming insoluble in the developer solution. The SU-8 2025 formulation is optimized for a wide range of film thicknesses, typically from 10 to 50 micrometers.
Automatically generated - may contain errors
Lab products found in correlation
Pdc 32g, by Harrick (2 mentions)
Su 8 developer, by MicroChem (2 mentions)
Fc 40, by Merck Group (1 mentions)
Autocad, by Autodesk (1 mentions)
Sylgard 184, by Dow (1 mentions)
Sylgard 184 silicone elastomer kit, by Dow (1 mentions)
Trichloro, by Merck Group (1 mentions)
H perfluorooctyl silane, by Merck Group (1 mentions)
Fluorinert fc 40 oil, by Merck Group (1 mentions)
Isopropanol, by Avantor (1 mentions)
Acetonitrile, by Avantor (1 mentions)
Methanol, by Avantor (1 mentions)
Sylgard 184 silicone elastomer kit pdms, by Dow (1 mentions)
Elix 3, by Merck Group (1 mentions)
Harris uni core 0, by Ted Pella (1 mentions)
Sylgard 184, by Thermo Fisher Scientific (1 mentions)
Autocad software, by Autodesk (1 mentions)
15 protocols using su 8 2025 photoresist
1
PDMS Microfluidic Device Fabrication
2
Fabrication of Double-Layer Microfluidic Chip
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The double-layer microfluidic chip was fabricated following the standard soft lithography described previously [11 (link),12 (link)]. Two pieces of the silicon molds, including the upper fluidic layer and the bottom staggered herringbone layer, were constructed from 20 μm high SU-8 2025 photoresist (Microchem, Westborough, MA, USA). The staggered herringbone mixer (SHM) structure was designed based on previous work [10 (link)]. Two polydimethylsiloxane (PDMS) layers were bonded through baking at 80 °C for 12 h to give a radial chip with 18 s-shaped airborne bacteria capture channels. Access holes of 1.5 mm diameter were drilled along the edge of the round chip of each channel to be used as inlet. Meanwhile, a 3.5 mm diameter hole was drilled in the center of the chip for air flow and bacteria-capture outlet, connecting the 18 airborne bacteria-capture units.
3
Fabrication of Microfluidic Devices with Photolithography
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Patterns of microstructures are fabricated on 3-inch silicon wafers with photolithography patterned Su8-2025 photoresist (Microchem Corp, MA, USA). The heights of photoresist were set to 60 μm, 20 μm and 45 μm, respectively, by different spin speeds for 70 μm droplet generation, 25 μm droplet generation and droplet merging chips. The patterns of the microfluidic channels were created in Autodesk AutoCAD software. PDMS (polydimethylsiloxane) prepolymer (Sylgard 184, Dow Corning Corp., MI, USA) and curing agent were mixed at a ratio of 10 : 1 and poured onto the wafer. After degassing and heating under 75 °C for 15 min, the PDMS was peeled off and the inlets and outlets both for the fluidic channels and electrodes were punched. The structured PDMS was then bonded with pre-heated PDMS substrates as described previously.23 (link) The temperature of the PDMS chips was kept above 60 °C until the electrode channels were filled with melted gallium indium alloy (52 °C gallium indium alloy, Abond Mechatronics Corp., Shandong, China). PTFE (polytetrafluoroethylene) tubes (id. 0.38 mm, od. 0.88 mm, Jinkairui Corp., Guangdong, China) were inserted into the inlets and outlets.
4
Fabricating Hydrophobic PDMS Microfluidic Devices
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SU-8 2025 photoresist (MicroChem, Westborough, MA, USA) is used to make master structures on a 3-inch silicon wafer using standard photolithography techniques. Curing agent and PDMS prepolymer (Momentive, Waterford, NY, USA; RTV 615) are mixed 1 : 10, degassed in a vacuum chamber, poured onto the master mold in a petri dish, further degassed until no bubbles are present, and baked at 65 °C for 4 hours. PDMS replicas are removed from the master, punched with a 0.75 mm biopsy punch (TedPella, Inc., Redding, CA, USA; Harris Uni-Core 0.75), bonded to glass slides (75 × 50 × 1.0 mm, 12-550C, Fisher Scientific) using a plasma bonder (Technics Plasma etcher), and placed at 150 °C for ten minutes to strengthen bonds. Devices are treated with Aquapel with a five-minute contact time and purged with air, rendering them hydrophobic. Devices are baked for at least 30 minutes at 65 °C to evaporate any remaining Aquapel.
5
PDMS Microwell Chip Fabrication
6
PDMS Film Fabrication and Mounting
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First, a layer of SU-8 2025 photoresist (MicroChem) was spin-coated onto a 100 mm wafer at 3000 rpm for 1 min. Then, after heating the wafer on a hot plate at 95°C for 2 min, a PDMS mixture at 12:1 (mass) ratio (base: curing agent; SYLGARD 184) was spin-coated on top of the SU-8 layer at 1200 rpm for 1 min. After curing the PDMS in an oven at 65°C for 2 hours, the film was released by immersing the wafer in a bath of mr-Dev 600 (micro resist technology). Then, the released film was transferred to a bath of toluene, which swells the film by 50%, and the film was quickly fixed afterward into an aluminum frame with a rubber O-shaped ring to retain the amount of swelling. Next, the film was washed using isopropanol and dried by nitrogen flow, which caused the film to shrink. The shrinking created a small amount of pretension that is needed to prevent wrinkling and folding of the PDMS when subjected to the frictional forces against the moving belt. Before placing the frame on the setup, a droplet of silicone oil with a viscosity of 5 mPa·s was placed in the middle of the film, which swells the middle part of the film, to reduce the pretension. Last, a lubrication oil (consisting of a mixture of W40 engine oil and the silicone oil) was applied on the belt to reduce friction and prevent tearing of the film. The process of mounting the PDMS film is shown in fig. S5.
7
Fabricating PDMS Microfluidic Devices
8
Fabrication of SU8 Microfluidic Devices
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3″ silicon test wafers (University Wafer, Catalog #447, Boston, MA) were rinsed extensively with acetone and isopropyl alcohol, then placed on a hotplate at 300 °C for a minimum of two hours to drive off water. Wafers were then coated with SU8 2025 photoresist (MicroChem Corp., Westborough, MA) and spun on a WS-400-6NPP spin coater (Laurell Technologies Corporation, North Wales, PA) using empirical protocols. After soft bake, photoresist was exposed on a Karl Suss MJB3 mask aligner (Suss MicroTec, Garching bei München, Deutschland) using transparency masks (printed by CAD/Art Services, Bandon, OR) mounted on a quartz slide (Chemglass Life Sciences, Vineland, NJ). Wafers were then post-exposure baked according to MicroChem protocol and developed using SU8 Developer (MicroChem). The thickness of resultant channel masks was confirmed at multiple locations using a NewView 7300 optical profilometer (Zygo Corp., Middlefield, CT), and re-verified after device assembly with fluorescence imaging. To facilitate later release of molded devices, wafers were treated with 1% v/v Trichloro(1 H,1 H,2 H,2H-perfluorooctyl)silane (Sigma-Aldrich Corp., St. Louis, MO) in hexanes for 5–30 minutes, dependent on ambient humidity, at room temperature and washed extensively with isopropyl alcohol before overnight hard bake at 80 °C in a hybridization oven.
9
Microfluidic Chip Fabrication Protocol
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Microfabrication. Microfluidic chips were generated using custom-made microfluidic master molds. The master molds were made using standard soft-photolithography processes using SU-8 2025 photoresist (Microchem, USA). The designs were made on AutoCAD (available upon request) to produce chrome photomasks (jd-photodata, UK). The observation device was taken from a previous study (Goulev et al. 2017) (link). The mold of the dust filter chip (see below for details) was made by spin-coating a 25µm layer of SU-8 2025 photo-resist on a 3" wafer (Neyco, FRANCE) at 2700 rpm for 30sec. Then, we used a soft bake of 7min at 95°C on heating plates (VWR) followed by exposure to 365nm UVs at 160 mJ/cm² with a mask aligner (UV-KUB3 Kloé®, FRANCE). Finally, a post-exposure bake identical to the soft bake was performed before development using SU-8 developer (Microchem, USA). The mold for the spiral-shaped cell filter device (see below for details ) was obtained by spinning SU-8 2025 at 1750 rpm to achieve a 50µm deposit. Bakes were 6 min long at 95°C and UV exposure was done at 180 mJ/cm². A hard bake at 150°C for 15min was then performed to anneal potential cracks and to stabilize the resist. Finally, the master molds were treated with chlorotrimethylsilane to passivate the surface.
10
Soft Lithography for PDMS Microfluidic Devices
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