Scanning magnetometer based on magnetoimpedance sensor for measuring a remnant magnetization of printed toners

In this work, a scanning magnetometer based on a giant magnetoimpedance sensor was used to study the toner material of a black-and-white laser printer that contains iron oxide nanoparticles. We measured the local perpendicular magnetic field component of various sizes black toner strips, magnetized in a perpendicular magnetic field. Our calibration samples were two-wire current lines, which are the current analogue of magnetized toner strips. Magnetic images of the samples were obtained. It was found that investigated toner samples have an average concentration of magnetic nanoparticles per unit area of order of 6 mu g/mm(2). At this concentration of nanoparticles, the remnant magnetic moment of the sample 1.6 x 5 mm(2) in size was about of 0.046 mu A.m(2) and could be reliably registered by the scanning magnetometer. The magnetic image of the toner sample was compared with a hysteresis loop obtained using a vibrating sample magnetometer.