Detection of Mycoplasma genitalium using a wireless magnetoelastic immunosensor

A wireless immunosensor for the detection of Mycoplasma genitalium was fabricated by immobilizing polyclonal antibody onto the surface of a magnetostrictive strip. In response to a time-varying magnetic field, the immunosensor longitudinally vibrates at a resonance frequency, emitting magnetic flux that can be remotely detected by a pickup coil. No physical connections between the immunosensor and the detection system are required, facilitating wireless aseptic operation. The binding of M. genitalium to the immunosensor surface resulted in a decrease in the resonance frequency of the immunosensor. When solutions with varying concentrations of the bacteria were tested, the shift of the resonance frequency was proportional to the concentration of M. genitalium. Under the optimized conditions, the linear range for the determination of M. genitalium was 2.0 × 103 to 2.9 × 104 color change units (ccu)/ml with a detection limit of 3.4 × 102 ccu/ml. The immunosensor was successfully applied to real samples containing M. genitalium with results similar to those previously obtained by the color change unit method.