From lateral flow devices to a novel nano-color microfluidic assay

Improving the performance of traditional diagnostic lateral flow assays combined with new manufacturing technologies is a primary goal in the research and development plans of diagnostic companies. Taking into consideration the components of lateral flow diagnostic test kits; innovation can include modification of labels, materials and device design. In recent years, Resonance-Enhanced Absorption (REA) of metal nano-particles has shown excellent applicability in bio-sensing for the detection of a variety of bio-molecular binding interactions. In a novel approach, we have now integrated REA-assays in a diagnostic microfluidic setup thus resolving the bottleneck of long incubation times inherent in previously existing REA-assays and simultaneously integrated automated fabrication techniques for diagnostics manufacture. Due to the roller-coating based technology and chemical resistance, we used PET-co-polyester as a substrate and a CO(2) laser ablation system as a fast, highly precise and contactless alternative to classical micro-milling. It was possible to detect biological binding within three minutes - visible to the eye as colored text readout within the REA-fluidic device. A two-minute in-situ silver enhancement was able to enhance the resonant color additionally, if required.