In modern biomedical research, environmental monitoring, and food safety, the demand for the detection of biological and chemical substances is increasingly shifting toward ultrahigh sensitivity, high specificity, and real-time responsiveness. As the concentration levels of target analytes—such as disease biomarkers, trace pollutants, and minute drug molecules—are often at the picomolar (pM) or femtomolar (fM) level, traditional detection methods are becoming inadequate to meet the growing demands for precise diagnosis and early warning.