An interrogating circuit and device for magnetostrictive biosensors

High performance biosensors for the detection of bacterial in various media have been developed using magnetostrictive/magnetoelastic resonators (MSRs). An MSR is a strip of magnetostrictive alloy coated with biological molecular recognition unit, such as antibody and phage. The sensor is based on the change in its resonant frequency. Therefore, it is critical to determine the resonant frequency of an MSR. The MSR biosensors have been developed for the detection of various pathogenic bacteria in liquid food and on the surface of fresh produce in real-time and in-situ manner. However, the instruments used to determine the resonant frequency of these sensors are bulky and expensive. Here an inexpensive circuit is developed to characterize the resonant frequency of the MRS sensors. The unique circuit design makes it is possible to have a real handheld device for the interrogation of MRS sensors. Additionally, a new methodology to enhance the signal is also introduced.