Contact-printed fNAP arrays. A print solution containing 3 μM nucleic acid probe, EDC, and NHS was prepared in MES buffer at a pH of 4.5. 10 μL of the solution was deposited onto polydimethylsiloxane stamps and incubated for 8 mins. Concurrently, glass slides wrapped with the target polyethylene substrate were carbon dioxide plasma-treated for three minutes. The solution was subsequently pipetted off, to permit control over residual volume present on the stamps. The stamps were then momentarily exposed to nitrogen flow, and then placed onto carbon dioxide plasma-treated substrates and weighed down with 500g of mass under 65% humidity.