A compact electromagnetic syringe stirrer and temperature controller for the reliable dispensing of living cells and microparticles

Lab-on-chip technologies frequently require biological samples, such as cells or microorganisms, to be maintained inside a syringe for prolonged periods of time during operations. Challenges include preventing cell sedimentation, ensuring cell viability, and maintaining buffer rheological properties (i.e. viscosity and density) constant, particularly in applications like 3D bioprinting and diagnostic assays. To address these challenges, we have developed the Syringe Electromagnetic Controller (SEC), an integrated system capable of simultaneously stirring and thermoregulating samples inside a syringe. SEC prevents sedimentation through the cyclic movement of a magnet actuated by an electromagnetic field, while maintaining a stable temperature (within ± 0.5 °C from a set-point) with a feedback loop. The system is compact, cost-effective, and easily integrated into various setups. Experimental validation shows that SEC effectively keeps living cells in suspension and at a constant temperature without compromising cell viability. Thus, we have ultimately demonstrated the functionality of SEC as a versatile solution for enhancing the reliability of lab-on-chip applications.