  Quantum sensing and imaging of magnetic fields has attracted broad interests
due to its potential for high sensitivity and spatial resolution. Common
systems used for quantum sensing require either optical excitation (e.g.,
nitrogen-vacancy centres in diamond, atomic vapor magnetometers), or cryogenic
temperatures (e.g., SQUIDs, superconducting qubits), which pose challenges for
chip-scale integration and commercial scalability. Here, we demonstrate an
integrated organic light emitting diode (OLED) based quantum sensor for
magnetic field imaging, which employs spatially resolved magnetic resonance to
provide a robust mapping of magnetic fields. By considering the monolithic OLED
as an array of individual virtual sensors, we achieve sub-micron magnetic field
mapping with field sensitivity of ~160 $\mu$T Hz$^{-1/2}$ um$^{-2}$. Our work
demonstrates a chip-scale OLED-based laser free magnetic field sensor and an
approach to magnetic field mapping built on a commercially relevant and
manufacturable technology.
