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

Abstract

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 [Formula: see text] technology and the magnetoresistive sensors were post-fabricated on top of the CMOS chip with high yield ( [Formula: see text]). Due to its low circuit noise (16 [Formula: see text]) and overall equivalent magnetic noise ([Formula: see text]), 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 ([Formula: see text] ) of the presented solution guarantees the portability of the detection system allowing its usage at the point-of-care.

Magnetoresistive biosensors with on-chip pulsed excitation and magnetic correlated double sampling

“…As such, this measurement is long enough for 1/ f noise (from both the sensors and the readout electronics) to severely distort the measurements. This is particularly true for GMR sensors which are known to have high 1/ f noise due to their multi-layer structure with multiple interface layers 21 , 32 , 39 , 40 . Correlated double sampling (CDS) is a classical circuit technique to suppress 1/ f noise 41 , 42 .…”

Detection techniques of biological and chemical Hall sensors

“…14,15 If required a momentary and enormous screening tests for diseases like Ebola and SARS, traditional bulky devices are not suitable. 16 Considering advantages of magnetic sensing technologies, the miniaturized systems bring down the size and cost because of benets from integrated thin-lm magnetic sensors like Hall sensors [17][18][19][20][21][22] giant magnetoresistance (GMR) 23,24,[24][25][26][27][28][29] and tunneling magnetoresistive (TMR) [30][31][32] and uxgate sensors, 33,34 etc. Although the GMR and uxgate sensors can be integrated with sensor readout circuitry to signicantly reduce system size [35][36][37] and they are more sensitive than Hall sensors to detect the weak magnetic eld, the used materials for fabrication are relatively not common in the foundry, which causes high cost for the GMR, TMR and uxgate sensors.…”

A readout circuit for tunnel magnetoresistive sensors employing an ultra-low-noise current source

“…1c, both the thermal and the flicker noise of the MOS current source typically dominate over the sensor and the frontend voltage amplifier, presenting the bottleneck for the achievable noise performance of the overall sensor system. To mitigate this problem, in [4], [5], the MOS transistor implementing the bias current source is embedded in a feedback loop to reduce its current noise.…”

“…However, in the implementations of [4], [5], the noise of the opamp inside the feedback loop significantly contributes to the total output current noise, limiting the presented noise floor to about 10 pA/…”