Fluorescence Imaging System Using a Repurposed Smartphone With Automated Signal Detection and Quantification

ABSTRACT Fluorescence imaging is a powerful technique widely used in biomedical diagnostics due to its high sensitivity and specificity in detecting biomolecular targets. However, conventional fluorescence imaging systems are typically expensive, bulky, and restricted to centralized laboratory settings, limiting their use in point‐of‐care and resource‐limited environments. This study presents a standalone, cost‐effective fluorescence detection platform developed from a repurposed smartphone and integrated with a custom mobile application for automated image acquisition, signal processing, and quantitative analysis. Quantitative image processing, including region‐of‐interest extraction and histogram‐based intensity measurement, was performed directly on the smartphone. The smartphone‐based measurements showed strong correlation with microscope data, with Spearman rank coefficients of 0.924 (4× objective) and 0.912 (10× objective), indicating high agreement in signal trends across both systems. This work demonstrates the feasibility of repurposing outdated smartphones to develop a fluorescence detection platform with measurement capabilities comparable to conventional fluorescence microscopes. Despite the absence of complex mechanical components such as translation stages and the use of only simplified optical elements, the system retains sufficient analytical performance for potential use in field‐deployable diagnostics and decentralized healthcare applications.