Microbial contamination and infection are important events related to life and health. The related biological micro/nano sensing detection system is an emerging frontier technology combining electronic information with life sciences, which involves the cross integration of materials science, micro/nano electronics, life science and information science. Aiming at the key problem of high-sensitivity signal extraction and signal conversion of target biomarkers in Giant Magneto Resistance (GMR) sensor sample detection method, this paper studies and develops a high-precision data acquisition instrument, which realizes the conversion of high-sensitivity biological signals to electrical signals and the amplification of multi-stage magnetic signals. The instrument can be used for the detection of soil, liquid, and food samples in multiple scenarios.