Sensitive Colorimetric Biosensors Based on Perovskite Heterojunction Phototransistors.

Colorimetry has held an important position in biomolecule detection due to its broad applicability, operational simplicity, and intuitively interpretable results. However, conventional colorimetric analysis relies heavily on bulky and complex facilities, which hinder miniaturization and limit its use for on-site rapid detection. Moreover, its sensitivity and dynamic range are constrained by the performance of traditional photodetectors. To address these limitations, this study introduces a novel colorimetric platform based on perovskite heterojunction phototransistors (PHP). Leveraging their inherent signal amplification as three-terminal devices, PHP can sensitively detect subtle absorbance variations induced by biomolecular reactions. The biosensing performance was evaluated through the detection of human immunoglobulin G (IgG) and glucose, achieving detection limits of 0.24 pM and 25.1 nM, respectively, and a dynamic range spanning 6 orders of magnitude─significantly surpassing conventional colorimetric systems. The proposed biosensor also exhibits high specificity and is low-cost and easy to operate, offering a promising avenue for the application of high-performance phototransistor-based biosensors in healthcare and early disease diagnosis.