A MAGNETIC MEASUREMENT SYSTEM BASED ON AN ULTRASENSITIVE PLANAR HALL MAGNETORESISTIVE BIOSENSOR (PHR) AND A METHOD FOR MEASURING LOW SPECIFIC BIOPARTICLES CONCENTRATIONS AND QUANTIFYING BIO-PARTICLES INTERACTIONS

摘要

A magnetic measurement system (2) for measuring a concentration of specific bio-particles through a sensitive detection of magnetic particle labels comprises an aptamer-based magnetic hybrid AMR/PHR sensor (12) having an active surface (22) on which at least one magnetic particle (28) is ready to be or is closely bound through a sandwich-type aptamer structure that includes a captured unitary bio-particle.;The magnetic measurement system is characterized in that an actual amplitude of an applied DC constant magnetic field onto the magnetic track (24) of the sensor (12) is closely located in a vicinity of an optimum amplitude of the permanent DC magnetic field comprised in a set of two optimum values H1, H2 of the permanent DC magnetic field, each optimum value H1, H2 maximizing locally the absolute value of a first quantity $H\cdot \frac{\partial V_{\mathit{MR}}}{\partial H},\mathop{\mathrm{image}}$ where H is the amplitude of the applied magnetic field and $\frac{\partial V_{\mathit{MR}}}{\partial H}\mathop{\mathrm{image}}$ is the derivate of the differential voltage with respect to the magnetic field at the applied field H.