Significantly improved analytical sensitivity of lateral flow immunoassays by using thermal contrast.

The ability to rapidly identify diseases enables prompt treatment and improves outcomes. This has increased the development and use of rapid point-of-care diagnostic devices capable of biomolecular detection in both high-income and resource-limited settings.[1] Lateral flow assays (LFAs) are inexpensive, simple, portable, and robust,[2] making LFAs commonplace in medicine, agriculture, and over-the-counter personal use such as for pregnancy testing. Although the analytical performance of some LFAs are comparable to laboratory based methods,[1a] the sensitivity of most LFAs is in the mM to μM range,[2–3] which is many folds less sensitive than other molecular techniques such as enzyme-linked immunoassays (ELISA). As a consequence, LFAs are not particularly useful for detection early in a disease course when there is low level of antigen. Due to the increasing need for highly sensitive molecular diagnostics, researchers have focused on developing microfluidics,[1a, 1b] biobar codes,[1c, 1d] and enzyme-based immunoassay technologies[4] technologies to fulfill the need since these technologies have nM to pM detection sensitivity for protein analysis and can potentially be miniaturized as handheld point-of-care diagnostic devices.[1c] These emerging technologies are still early in development and are not yet field-ready.