A CMOS Front-End With Integrated Magnetoresistive Sensors for Biomolecular Recognition Detection Applications

The development of giant magnetoresistive (GMR) sensors has demonstrated significant advantages in nanomedicine, particularly for ultrasensitive point-of-care diagnostics. To this end, the detection system is required to be compact, portable, and low power consuming at the same time that a maximum signal to noise ratio is maintained. This paper reports a CMOS front-end with integrated magnetoresistive sensors for biomolecular recognition detection applications. Based on the characterization of the GMR sensor's signal and noise, CMOS building blocks (i.e., current source, multiplexers, and preamplifier) were designed targeting a negligible noise when compared with the GMR sensor's noise and a low power consumption. The CMOS front-end was fabricated using AMS 0.35 mu m technology and the magnetoresistive sensors were post-fabricated on top of the CMOS chip with high yield (97.9%). Due to its low circuit noise (16 nV/root Hz) and overall equivalent magnetic noise (11.5 nT/root Hz), the full system was able to detect 250 nm magnetic nanoparticles with a circuit imposed signal-to-noise ratio degradation of only -1.4 dB. Furthermore, the low power consumption (6.5 mW) and small dimensions (7.59 mm(2)) of the presented solution guarantees the portability of the detection system allowing its usage at the point-of-care.