Comparison of reference sensors for noise cancellation of magnetoelectric sensors
Thin film magnetoelectric (ME) sensors offer a promising potential to measure biomagnetic signals in the near future. Unfortunately, this sensor type shows usually a large cross sensitivity to all kinds of mechanic distortion due to the resonant structure. In order to overcome this problem several sensor designs have been proposed. Beside these approaches adaptive noise cancellation techniques can be used to reduce the noise coupling while keeping the sensor setup simple. In this contribution reference sensors, realized as piezoelectric cantilevers, are presented and compared to microphones by means of their feasibility to improve the signal to noise ratio (SNR) using adaptive cancellation approaches. If a loudspeaker is used as noise source, no crucial differences are measured. But if a vibrator is used as noise source to generate structure borne noise, the piezoelectric (PE) cantilevers are superior. As the difference of the resonance frequencies between ME and PE sensor is decreased the SNR improvement increases at low excitation levels. In total an SNR improvement over 30 dB can be achieved.
2016 IEEE SENSORS