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