A Chip-based Miniature MRI Platform with Integrated Frontend Probe for In-Situ 3D Cell Culture Monitoring

Three-dimensional (3D) cell culture is gaining attention for its ability to better mimic tissue environments in vitro, enhancing drug screening efficiency. Tracking biological dynamics in such a setup requires advanced monitoring technologies. This paper presents a miniature magnetic resonance imaging (MRI) platform tailored for imaging 3D cell-culture morphology within a microliter-volume microwell, enabling real-time and on-site visualization of biological dynamics. The system utilizes an MRI application-specific integrated circuit for excitation and detection of the nuclear magnetic resonance (NMR) signal. To cope with the small-volume sensing, the platform features a customized frontend probe, which includes a miniaturized saddle coil and a PDMS-molded sample well for in-situ microliter sample containment and detection. Our proof-of-concept measurements on samples demonstrate an MRI image resolution of 90×128×88 $\rm \mu m$^³, along with continuous, multi-perspective (transverse and longitudinal) imaging of 3D cultures, including spheroid slice visualization. These results highlight the system's applicability and potential for future biological analysis and drug screening, offering researchers a valuable tool for advancing in vitro studies.