Figure 1

(a) Barcodes of “−” and “+” symbols as created using Code 39. The two characters (highlighted with the red brackets above and below the barcodes) are identical apart from the 4 elements in the middle of each character (dashed green box); start and stop characters are denoted by “*” (highlighted with the blue brackets). (b) Enlarged image demonstrating the design of the assay strips, as patterned using a microfluidic PDMS chip. The wide bars of the “−” character have been “divided” into four separate binding strips. The first and third serve as test lines while the second and fourth serve as control lines for the test. Barcodes are scanned by placing the PC plate atop a piece of paper with printed barcode, apart from the strips indicated in the green dash-line box. In the case of a positive test, all channels will produce a visible signal that can be scanned, reading as “−”, while in a negative test, only channels two and four will produce a signal, reading as “+”.