Recent Progress in BiFeO₃-Based Sensor Technologies: Fundamentals, Performance Metrics, and Diverse Applications

Bismuth ferrite (BiFeO₃, BFO) is a prototypical multiferroic perovskite that simultaneously exhibits ferroelectricity, antiferromagnetism, piezoelectricity, and strong visible-light absorption due to its relatively narrow band gap. The interplay among lattice distortions, defect chemistry, and orbital hybridization not only underpins these multifunctional responses but also renders them highly tunable through defect-dipole modulation, band-gap engineering, and interface or surface control. Owing to the unique coupling between ferroic and electronic functionalities, BFO has emerged as a versatile platform for next-generation sensing technologies, including optoelectronic, pressure, gas, humidity, and biosensors. This review systematically examines the structure-property relationships in BFO, recent advances in synthesis and modification strategies, and their implications for sensor performance across diverse domains. Special emphasis is placed on the microscopic mechanisms governing its sensing behavior, including band-structure modulation, defect-mediated charge transport, and surface adsorption-driven chemistry, as well as on strategies to leverage these mechanisms for sensing performance optimization. Finally, we outline the opportunities and challenges in harnessing BFO's multifunctionality for practical sensing applications in environmental, healthcare, industrial, and energy-related fields.