Scanning superconductivity quantum interference device（SQUID）microscopy with sample handling unit and the movable and positioning sample platform

can realize measurement of the magnetic characteristics and magnetic field distribution of magnetic particles in biological sample.The magnetic field detecting unit is an important component of the system.Introducing the structure and detection principle of the magnetic field detecting unit

deriving conversion formula of the magnetic flux

magnetic field and voltage

establishing magnetic particle model

and analyzing the influence of different coil parameters on the magnetic field sensitivity and spatial resolution through simulation.Superconducting receiving coil with diameter of 500μm

30turns is made

magneti

c field sensitivity is 1.46×10-13T/（Hz）

1/2

and spatial resolution is 500μm.Magnetic particle model and simulation analysis provide theory basis for system design and experimental data analysis.