We have developed a laser-direct write (LDW) technique that allows the fabrication of LFDs with enhanced sensitivity and improved limit-of-detection. This LDW technique comprises of the deposition of a photo-polymer and its subsequent photo-polymerisation to create specifically shaped impenetrable walls within the nitrocellulose membrane section of an LFD that hosts the test-zone. These polymerised walls are intentionally designed to create constrictions of a specific width at the test-zone within which the sample interacts with pre-deposited reagents.
The constriction has the effect of reducing both the flow-rate and the size of the test-zone. This thereby results in an increased incubation-time and an increased reagent concentration at the test zone, producing an increased sensitivity and lowered limit-of-detection for these devices.
We have implementated a CRP-assay on our proposed LFD, which shows sensitivity and limit-of-detection improvements of 62x and 32x respectively when compared to a standard LFD.