Microfluidic moulds were made by photolithography. The photomask motif was designed and printed by computer-aided design software (DraftSightTM, Dassault Systèmes, France) and a photoplotter (FPS25000, Fortex Engineering Ltd., UK). Dry photoresist films (SY300 film, Fortex Engineering Ltd., UK) with a final thickness of 150 μm were attached to a 75 × 50 × 1 mm glass slide (12-550 C, Fisher Scientific, Canada) using a dry film laminator (FL-0304-01, Fortex Engineering Ltd., UK). The photomask was combined against the laminated photoresist surface and exposured to UV light (AY-315, Fortex Engineering Ltd., UK). The unexposed photoresist was dissolved by the developer and rinse solutions (SY300 Developer/Rinse, Fortex Engineering Ltd., UK). Two graphite electrodes (Isomolded Graphite Plate, Graphitestore.com Inc., USA) were covered with a protective laminate and placed onto the mould in a side-by-side arrangement such that their overlap with the channel would result in an exposure area of 3 × 10 mm. Then a mixture of PDMS and a cross-linker was poured over the mould, and the assembly was cured at 70 °C overnight. Four inlets and three outlets were punched into the device to admit fluid conduits. Two glass plates were plasma bonded (PCD-001, Harrick Plasma, USA) for 90 seconds at 600 mTorr to the device. One to seal the channels (on the bottom side) and the other was placed on the outer surface (top side) to prevent oxygen penetration through the air-permeable PDMS material. Inlets and outlets were connected to connective tubing (PFA tube 1/16", Hamilton Inc., Canada) that were made gas-impermeable using a layer of gas-impermeable tape (Loctite 249 Anaerobic Blue Threadlocker Tape, Medium Strength, Henkel Corp., Canada), and an epoxy coating (LOCTITE Epoxy, HenKel Corp, Canada). The same epoxy was applied to all remaining exposed PDMS. Gas tight glass syringes (DGA glass syringe, 50 mL, Sigma-Aldrich, Canada) were connected to the tubing and operated at selected flow rates by syringe pumps (PhD 2000, Harvard Apparatus, MA). (d) Cross-section schematic (y-z plane) showing 150 µm channel height, and device fabrication materials: PDMS (blue), graphite (black), glass cover slip and outer layer sealing protection (grey), epoxy walls (yellow). Outlet 2 is not shown as it is blocked after membrane formation.