A Fully Integrated GMR Biosensor with On-Chip Coils and Sensors Achieving 605 Resolution FoM for Multiplexed PoC Diagnostics

This paper presents a fully integrated GMR biosensor chip for point-of-care in vitro diagnostics featuring on-chip sensors, excitation coils, and a digital back-end. The system achieves <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$120 \text{nT}_{\text {rms }}$</tex> noise, 0.38 ppm sensitivity, <0.2% mismatch, and a resolution FoM of 605, outperforming prior GMR designs with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$21 \times$</tex> faster readout and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10 \times$</tex> lower baseline with full integration. Real-time IL-6 immunoassay results demonstrate high specificity and multiplexing, enabling compact, high-throughput PoC testing.