Nanogenerator and piezotronic inspired concepts for energy efficient magnetic field sensors

Highlights: • Two new strategies to enhance performance of magnetic field sensors. • Piezotronic sensor read-out for lower noise and higher energy efficiency. • Electret based sensor for large bandwidth operation at low frequencies with high amplitude. -- Abstract: Inspired by recent developments in the field of nanogenerators and piezotronics, two different approaches for the improvement of magnetic field sensing are discussed and their feasibility has been experimentally demonstrated. In the first concept, it could be shown that a piezotronic read-out eliminates the need for an external pre-amplifier in MEMS type cantilever sensors. This leads to reduced noise and lower power consumption, which makes the sensors interesting for self-powered applications. Furthermore, the lower noise is measured at short integration times, which reveals further application strategies for piezotronic sensor read-out. In the second concept, a new nanogenerator inspired utilization of electret film allows a reduction of the resonance frequency of cantilever sensors. This reduction is accompanied by higher amplitudes and lower Q-factors allowing energy efficient broadband measurements. A theoretical model has been developed based on an anharmonic oscillator, which is in good agreement with the observed experimental results. Both the demonstrated strategies can help to improve the energy efficiency of the presented magnetic field sensors, allowing lower power consumption and a decreased noise level.