High-efficiency microfluidic chip integrating with micropatterned planar spiral sensors for magnetic nanoparticle detection

Magnetic nanoparticles have garnered significant attention in the biomedical field due to their remarkable biocompatibility and diverse applications. However, existing methodologies for quantifying magnetic-labeled samples face limitations, particularly regarding the stringent requirements for magnetic sensors and the complexities associated with integrating these systems into microfluidic platforms. This study introduces an innovative planar magnetoimpedance sensor for magnetic nanoparticle detection, designed with a micropatterned spiral configuration and integrated into a microfluidic channel. The spiral configurations of the planar sensor are designed and optimized through micromagnetic simulations, where the domain properties of the sensors are examined by varying the turn widths of the spiral micropatterns from 70 μm to 210 μm. The optimal width is identified at 70 μm for effective measurement of magnetic particles. The magnetoimpedance sensor is fabricated using wet chemical etching based on an FeSiC ribbon. The computation-guided design of the magnetoimpedance sensor achieves impressive sensitivity and resolution values of 2.5% Oe-1 and 0.01 Oe, respectively. The designed sensor, integrated with the microfluidic channel, can detect magnetic nanoparticles as small as 0.2 μg. Both experiment and simulation results demonstrate that the magnetoimpedance effect is significantly influenced by the configurations of the transverse magnetic domain, resulting in detectable variation of the stray field in the MI sensor's output signals. Integrating the magnetoimpedance sensor with the microfluidic system provides several advantages, including cost-effectiveness, rapid response times, and user-friendliness. This quantitative detection method for magnetic nanoparticles holds substantial promise for applications in biological concentration detection and other advanced research domains.