High-sensitivity detector for molecular sensing using magnetic particles

A scheme for molecular sensing using magnetic tracer particles and a microcantilever torsional magnetometer is investigated. The present report deals with the example of explosive 2,4,6-trinitrotoluene (TNT) detection. The sensors consist of silicon microcantilevers functionalized with TNT aptamers that are weakly bonded to magnetic particles via TNT-analog molecules. When exposed to TNT, the magnetic signal, initially maximum, is expected to undergo a steplike decrease as the TNT molecules replace the magnetic particles on the TNT receptors. We demonstrate the feasibility of this detection technique in terms of chemical reactions and our magnetometer sensitivity that reaches the range of 10 − 11 emu at room temperature with commercial atomic force microcopy cantilevers.