Embodiments of the invention relate generally to ferromagnetic microdisks, methods of detecting target bioanalyte using ferromagnetic microdisks, and kits (such as for using in the laboratory setting) containing the reagents necessary to make, and/or use ferromagnetic microdisks for bioanalyte detection, depending on the user's planned application. The methods and products allow the fabrication of ferromagnetic microdisks, and their use in the detection of biological molecules with high sensitivity, little or no signal decay, improved safety, convenience, and lowered cost for use and disposal.