Development of Enhanced Lateral Flow test Devices for Point-of-Care Diagnostics

Lateral flow Imunoassays (LFIA) are common, simple to use point-of-care devices for the diagnostic market. Conventionally LFIAs are limited in their complexity since they are optimized for minimally trained operators. Paper-based analytical devices (PAD) are advanced sensors based on a wide range of recently developed techniques for complex analytical methods. In this research, a point-of-care (POC) immunosensor was developed based on techniques adapted from lateral flow and paper-based analytical devices. Alternating layers of paper and tape were used to expand the common 2D design of lateral flow tests to 3D in order to enable complex fluid flow control. Four fluidic valves were integrated for automatic sequential loading of three different fluids to a detection area. Fabrication processes, reagent concentrations, materials and device geometries were optimized and a chip-yield of 92% was achieved. A three step alkaline phosphatase (ALP)-based enzyme-linked immunosorbent assay (ELISA) procedure with Rabitt IgG as model analyte was used to prove the working principle of the sensor. After optimization of crucial assay parameters practicability was verified by visual detection of signal development on nitrocellulose membrane after reaction of ALP and NBT/BCIP with a good detection limit of 4.8 fm