Figure 6.

Photos of a multi-channel fluidic system fabricated for simultaneous detection of analytes. The as-prepared substrates with pre-loaded urease of concentration 50 mg ml⁻¹ and pH marker are seen in (a). From left to right (1–4), the volume of urease immobilized on the reaction zone was 10, 20, 20 and 0 µl (control). (b) The multi-device after the test was performed using 30 µl of 1 M urea dispensed in the common port of entry. From left to right (1–4), the first three reaction zones shows a change in colour indicating that enzymatic reaction had taken place. The fourth reaction zone shows no colour change expected from a substrate with no pre-loaded enzyme.