Autocad 2007

The schematic diagram of the device is as shown in Fig. 1A. The device was composed of two layers of polydimethylsiloxane (PDMS) with several microchambers. The top layer of the chip has one cell culture chamber which was 500 µm in height, 6 mm in width and 11 mm in length and the bottom layer has three microchambers, each of which was 500 µm in height, 2 mm in width and 16 mm in length. Between two pieces of PDMS, there was a polycarbonate membrane (Whatman Inc., Piscataway, NJ, USA), with the pore size of 0.4 µm, which allowed the transition of cytokines and small molecular compounds (19 (link)). Each chamber has one inlet and one outlet, respectively. Perfusion system could be linked with the inlet of each chamber to provide the fluid flow.
Microfluidic chip was fabricated using a conventional microfabrication technique. The mask was designed by AutoCAD 2007 (Autodesk, Inc., San Rafael, CA, USA) and printed on transparencies with 4,000 dpi resolution. The master was fabricated by photoresist SU-8 3035 through soft lithography technique. Then the microfluidic chip was fabricated in PDMS by replicating molding the master, followed by the curing process of PDMS at 80°C in an oven for one hour. After that, PDMS layer was peeled off from the master. A polycarbonate membrane and two pieces of PDMS were sealed together after the treatment by oxygen plasma for 1 min.

The microfluidic chip was fabricated by using AutoCAD 2007 (Autodesk, USA) and a CO₂ laser machine (LaserPro Venus, GCC, Taiwan) for constructing channel patterns on a “poly(methyl methacrylate) (PMMA)” plate (length/width/depth: 270 mm/210 mm/1.5 mm), as described previously.^{29–32 (link)} The microfluidic chip (length/width/depth: 86 mm/50 mm/6 mm) consisted of three PMMA chips, namely the cover chip (with three inlets for sample injection and twenty screw orifices for binding), the middle chip (with a cross-junction channel and twenty screw orifices), and the bottom chip (with an outlet and twenty screw orifices). The three chips were integrated using screws (0.5 mm pitch, 4 mm diameter), as illustrated by ESI Fig. S1.† The microfluidic chip could be disassembled for reuse and cleaning by loosening the screws.^{29–32 (link)}