Su 8 2050 negative photoresist

In this paper, SU-8 2050 negative photoresist and propylene glycol methyl ether acetate (PGMEA, 1-methoxy-2-propanol acetate) developer (MicroChem Corp., Westborough, MA, USA) were used to prepare the micro electroforming mold. Polished 1 mm thick stainless steel (1Cr18Ni9Ti) sheet was employed as the substrate. An n-methyl pyrrolidinone solution was used to remove the cross-linked SU-8 structure after micro electroforming. The structures and roughness were examined using a confocal laser scanning microscope (CSLM, Olympus LEXT OLS4000, Olympus Corporation, Tokyo, Japan).

The entire microfluidic device consists of three layers: the sample layer, the buffer layer, and the top microchannel layer. The sample layer and buffer layer were fabricated by molding processed polymethyl methacrylate (PMMA) templates. The microchannels were fabricated by standard photolithography techniques [38 (link)]. The patterns of the chip were designed using AutoCAD 2022 (Autodesk, San Francisco, CA, USA), and SU-8 2050 negative photoresist (Microchem, Newton, MA, USA) was spin-coated onto the pretreated silicon wafer to create a 40 μm high photoresist layer. After spin coating, the baked wafer was exposed to 365 nm UV. The patterned wafer was baked again and developed using a SU-8 developer (Microchem). The polydimethylsiloxane (PDMS, Dow Corning Sylgard 184) was mixed with a curing agent at a 10:1 ratio, poured onto the PMMA templates and patterned wafer, and cured at 80 °C for 2 h. The cured PDMS replicas were peeled off. A puncher with a 1.00 mm inner diameter was used to punch inlet holes for the microchannel of the PDMS device. After plasma treatment, the cured PDMS chips were brought into contact and heated in an oven at 80 °C to achieve an irreversible bonding. For more details see Supplementary Materials (Figure S1).

Luria Bertani (LB) broth are composed of 0.5% yeast extract, 1% peptone, 1% NaCl and deionized water, all of which were purchased from Beijing Ao Xing Bio-tech (Beijing, China). Ethanol and amoxicillin were obtained from Sigma-Aldrich (Shanghai, China). SU-8 2050 negative photoresist was purchased from Micro Chem Corp. (Newton, MA, USA). Polydimethylsiloxane (PDMS) Sylgard 184 was obtained from Dow Corning (Midland, MI, USA). Borosilicate glass was achieved from Matsunami (Kyoto, Japan). FilmTracer TM SYPRO^® Ruby Biofilm Matrix Stain was purchased from Invitrogen (Waltham, MA, USA).