Highly Improved Sensitivity of FET Sensors Based on a Pulsed Temperature Profile for Lead Ion Detection

This study presents the development of a lead-based molecular probe integrated with an extended-gate field-effect transistor (EGFET) for the highly sensitive detection of lead ions (Pb²⁺). The molecular probe was carefully selected and engineered to exhibit a strong binding affinity for Pb²⁺ while maintaining both thermodynamic stability and structural robustness. To enhance sensing performance, we employed a pulsed temperature profile strategy that accelerates molecular interactions and overcome energy barriers, followed by a stabilization step to preserve the integrity of the formed complexes. Through this approach, the sensor achieved an ultralow detection limit of 1 pM, highlighting the crucial role of molecular probe structural stability and thermodynamic properties in improving overall sensing efficiency. DNA linkers functionalized with reactive groups and fluorescent labels were employed to enable real-time monitoring of surface modification and facilitate efficient molecular immobilization, thereby enhancing the sensor's versatility. Moreover, constructing a monolayer sensing interface allowed direct regulation of the electric double layer (EDL), resulting in rapid signal responses. Selectivity tests confirmed the sensor's preferential interaction with Pb²⁺ ions. Overall, this study developed an innovative sensing platform that achieves ultralow detection limits and high selectivity for Pb²⁺. The platform is highly versatile and can be extended to EGFET-based sensing of a wide range of molecules.