A Novel Method for Magnetic Isolation and Characterization of Polycarbonate-Urethane Wear Particles

Ferrography is a method for separating wear particles onto a slide. The method is based on the interaction between an external magnetic field and the magnetic moments of the particles suspended in a flow stream. It is advantageous in providing high detectability rate for a relatively large range of particle sizes (0.5–200 μm) [1]. A newer generation of ferrography, known as Bio-Ferrography, allows particles from five fluid samples to be isolated simultaneously on one slide and analyzed in terms of their number, chemistry, shape, dimensions, surface morphology, structure, etc. Since magnetization does not naturally occur in polymeric and biological materials, wear particles of such origins must be magnetized prior to Bio-Ferrography. This can be done, for instance, by binding to a ferromagnetic element, such as Er⁺³, originating from erbium chloride (ErCl₃) solution. Such Bio-Ferrography technology has already been applied successfully in hip wear simulations for the separation of ultrahigh molecular weight polyethylene (UHWPE) wear debris suspended in bovine serum as lubricant [2].