Magneto-optical microscopy platform for quantitative imaging of hemozoin in blood for malaria diagnosis.

Malaria remains a major global health challenge, particularly in low-resource settings where diagnostic infrastructure is limited. The gold standard diagnostic is manual light microscopy which is slow, labor-intensive, and dependent on expert interpretation limiting the management of malaria. Here, we present a magneto-optical (MO) imaging approach that exploits the magnetic anisotropy and optical dichroism of hemozoin crystals to achieve label-free, quantitative detection of malaria infection within a conventional polarizing microscope. In our implementation, an external magnetic field induces torque on the paramagnetic hemozoin crystals, aligning their long axes along the field vector. This alignment modulates the optical anisotropy of the specimen, producing a measurable field-dependent change in transmitted polarization contrast. Unlike previously reported standalone magneto-optical devices, which rely on bulk optical scattering or transmission modulation, our approach integrates MO directly into a conventional polarizing microscope setup, allowing simultaneous imaging and quantitative MO signal analysis at the microscopic scale. By integrating ratiometric intensity analysis and threshold-based segmentation metrics, we advance malaria imaging beyond purely observational assessment, enabling a quantitative correlation between MO signal strength and hemozoin concentration, and thus, with parasite developmental stage. These metrics are also well-suited for automated malaria diagnostics, as they provide stable, objective parameters that can be reliably computed without expert intervention. Moreover, because microscopy expertise is already well established in many malaria-endemic regions, embedding this approach within the familiar framework of microscopy offers a practical and rapid pathway for integrating the technique into routine malaria diagnosis.