Achieving highly sensitive and specific detection of human IgG and glucose is of great significance for early disease diagnosis and efficacy evaluation. Although traditional methods such as ELISA and PCR are sensitive and reliable, their complex operation and high costs make them difficult to meet the needs of on-site rapid testing. In contrast, colorimetric methods, with advantages such as simple operation, intuitive results, and low cost, are widely used in clinical diagnosis, food safety, and environmental monitoring. Based on the Lambert-Beer law, phototransistors can achieve quantitative detection of target analytes by measuring changes in absorbance caused by color development reactions. By modulating the electric field and photo-regulating channel carrier density, phototransistors possess high gain and internal signal amplification capabilities, demonstrating significant potential in the field of biosensing. Perovskite materials have become ideal photosensitive layer materials due to their high light absorption coefficient, tunable bandgap, and long carrier diffusion length. To overcome the limitations of traditional colorimetric biosensors, such as low sensitivity and narrow dynamic range, this study employs a PCBM/MAPbI3 heterostructure to construct phototransistors, utilizing the charge trapping effect (CTE) to achieve highly sensitive responses to subtle light absorption changes.

This study aims to enhance sensitivity, broaden the dynamic range, and simplify the system by proposing the use of a PCBM/MAPbI₃ planar heterojunction structure. With MAPbI₃ serving as the conductive channel and photosensitive layer, and PCBM as the electron acceptor layer and interface passivation layer, the formed Type II heterojunction effectively promotes exciton dissociation and charge carrier separation. The photogenerated electrons are captured in PCBM, while holes migrate in the MAPbI₃ channel to form photocurrent gain. The sensor exhibits excellent linear response within the range of human IgG concentrations from 100 pg/mL to 100 μg/mL, with high sensitivity and a detection limit as low as 0.24 pM. Compared to various human IgG sensors reported in recent literature, its detection performance is significantly improved, making it widely applicable in the field of trace biomolecule detection.

Source: Sensor Expert Network