In-line monitoring of magnetic microparticles using GMR sensors in microfluidic systems

This paper presents the development of a giant magnetoresistive (GMR) sensor array for the in-line monitoring of magnetic microparticles in microfluidic systems. The GMR sensors employ Ni80Fe20/Cu multilayers with the thickness of each layer controlled between 1 nm to 3 nm, achieving a maximum magnetoresistance (MR) value of 16%. The multilayer films exhibit specific magnetoresistive properties that can be employed for the in-line detection of particular biological molecules bound to magnetic microparticles. The electrical current variations in the developed GMR sensor array in the presence of magnetic microparticles show that the GMR sensor array can be used for real-time monitoring of magnetic microparticles in microfluidic systems