Wireless electrodeless piezomagnetic biosensor with an isolated nickel oscillator

This study presents a fundamental concept of piezomagnetic biochemical sensor driven in a wireless-electrodeless manner. A stepped cylindrical rod of nickel is used as the oscillator, which traps the vibrational energy of axially-polarized surface-shear waves in the central part, where the diameter is slightly larger. A meander-line coil surrounding the oscillator with an air gap can cause and detect the resonant vibrations of the surface-shear waves via the piezomagnetic effect. The resonant frequency of the trapped-mode resonance is continuously measured to detect human immunoglobulin G (IgG). It decreased by 0.08% when a solution containing IgG was injected into the glass cell where the oscillator was placed alone. This oscillator is useful for fundamental studies of various biochemical reactions in a closed system in different environmental gases and different pressures.