Recent Progress of Electrochemiluminescence Imaging for Single‐Entity Analysis

Electrochemiluminescence (ECL) has become an indispensable analytical technique in bioanalysis due to its near‐zero background noise, high sensitivity, wide dynamic range, cost‐effectiveness, and simple instrumentation. Conventional ECL methods focus on ensemble‐averaged measurements, the inherent heterogeneity of biological systems necessitates single‐entity analysis to reveal hidden mechanisms and rare events obscured in bulk assays. Recent advances in ECL microscopy have enabled the interrogation of diverse single‐entity, spanning single cells, bacteria, molecules, and nanoparticles, offering unprecedented insights into their physicochemical and biological properties. This review begins with a concise introduction to the fundamental principles and unique advantages of ECL. Subsequently, it systematically summarize cutting‐edge applications of ECL imaging across multiple scales, emphasizing breakthroughs in single‐cell analysis, single‐bacteria detection, single‐molecule resolution, and single‐nanoparticle characterization. Finally, it thoroughly discuss persistent challenges and future directions, such as improving spatial resolution, developing new and efficient ECL emitters, and integrating machine learning algorithms with ECL imaging.