There has been a long-standing interest in controlling and instrumenting the human body. Whether to restore lost function with neural prosthetics, monitor blood glucose levels, or augment human capabilities, there are countless opportunities for sensors inside ( e.g., ingestible, injectable, and implantable) and outside ( e.g., wearable) the body. However, many challenges exist when instrumenting the body. First, many use cases ( e.g., implanted sensors) require long-term recording to capture anomalous behavior—sometimes with limited accessibility—necessitating ultralow power consumption. Second, the power reduction challenge is further exacerbated by size constraints, which limit battery capacity or harvestable energy levels. Third, the signals of interest are often low bandwidth (kHz) and small in amplitude (µV to mV); thus, low-noise front ends are needed. Addressing these challenges has led to a large body of work on the design of highly power-efficient, low-noise amplifiers for biomedical integrated circuits.@en

Magnetic nanotechnologies have shown significant potential in several areas of nanomedicine such as imaging, therapeutics, and early disease detection. Giant magnetoresistive spin-valve (GMR SV) sensors coupled with magnetic nanotags (MNTs) possess great promise as ultra-sensitive biosensors for diagnostics. We report an integrated sensor interface for an array of 256 GMR SV biosensors designed in 0.18 μm CMOS. Arranged like an imager, each of the 16 column level readout channels contains an analog frontend and a compact ΣΔ modulator (0.054 mm2) with 84 dB of dynamic range and an input referred noise of 49
nT/√Hz. Performance is demonstrated through detection of an ovarian cancer biomarker, secretory leukocyte peptidase inhibitor (SLPI), spiked at concentrations as low as 10 fM. This system is designed as a replacement
for optical protein microarrays while also providing real-time kinetics monitoring.@en