Novel Flexible Wearable Field-Effect Transistor Aptasensor with DNA Hydrogel for In Situ Wireless Detection of Organophosphorus Pesticide Residues

Organophosphorus pesticides (OPs) are widely applied for crop pest control, but human health and the environment are seriously threatened by their excessive use. Therefore, rapid detection of pesticide residues is of great importance. In this work, a flexible aptasensor was developed by integrating an indium oxide electrolyte-gated field-effect transistor (EG-FET) with a surface-adhered DNA hydrogel obtained via rolling circle amplification (RCA) for in situ detection of OPs residues. The target pesticides were specifically recognized by the responsive DNA hydrogel, which underwent structural collapse and consequently modulated carrier depletion in the n-type FET channel. Furthermore, a wireless detection device based on a dual-channel potentiostat and a smartphone-based human-machine interface was established, enabling the detection of four OPs, including omethoate (OMT), phorate (PHO), isocarbophos (ICP), and chlorpyrifos (CPF). The EG-FET aptasensor exhibited a good linear relationship between signal response and pesticide concentration in the range of 1 pg/mL–10 ng/mL, with the limit of detection of 0.244, 0.273, 0.132, and 0.301 pg/mL, respectively. The developed device was characterized by compactness and low-cost fabrication. This work proposes a new approach to detecting small-molecule contaminants, opening avenues for transforming agricultural, food safety, and environmental monitoring from passive post-event detection to active process control.