Effective testing for HIV allows for detection of acute infections (new and rebound), appropriate antiretroviral treatment, suppression of viral load, and interruption of transmission. However, early detection of infection or regular self-monitoring at point-of-need or at home remains a challenge. Lateral flow assays are a well-established, inexpensive point-of-need diagnostic method, and commonly are favored when applicable because of their ease of use and low cost. Where they most commonly fall short is in analytical sensitivity, notably in antigen-detection diagnostics for infectious diseases. Our goal is to develop radically-improved LFAs by implementing the inexpensive, shelf-stable chemi-excitation chemistry of glow sticks in a point-of-care format to excite fluors without light or optical filters. Our preliminary results suggest this chemistry enables LFAs with greatly improved limits of detection (very low pg/mL), using a standard smartphone with a $2 adaptor and no sophisticated optical components. Our central hypothesis is that our novel, reagent-optimized chemi-excited lateral flow assay technology integrated with a storage-stable reagent cartridge and readable with a smartphone will lead to a new, widely-useful and potentially very-superior class of highly-sensitive lateral flow assays. We will test this hypothesis through 5 specific aims: (1) Development of a highly-sensitive and easily-usable lateral flow assay for HIV p24 in human blood, including development of novel avidity-enhanced dual-fibronectin-domain binders, (2) Immune complex dissociation (ICD) for rebound/breakthrough HIV diagnosis, (3) Testing with 300 negative and archived-positive human samples from diverse cohorts, (4) To evaluate clinical performance using fresh samples from patients and usability with a diverse population of subjects at high risk of HIV infection/rebound (R33 Phase), (5) Easier usability by more people, quality assurance for test items (R33 Phase).