A self-powered magnet-less tunable piezoelectric vibration sensor based on stress distribution

This paper presents a self-powered tunable piezoelectric vibration sensor based on stress distribution. The piezoelectric sensor features split electrodes to adjust the resonance frequency. Turning electrically OFF configurable electrodes changes the sensor stiffness by varying the stress level. Unlike previous works, the proposed tunable sensor does not use a magnet or an auxiliary mass. The effect of the tuning mechanism on the resonance frequency, voltage sensitivity, and power density has been investigated through theoretical analysis, simulation, and experimentation. The paper explores the effect of the stress level on sensor linearity. The paper also examines the impact of thickness and length on the frequency tuning range. The tuning mechanism achieves a tuning range of 8.6 Hz with a thickness ratio of 0.2 and a length of 90 mm, surpassing the capabilities of most fine-tuning mechanisms. The tunable sensor has a good linearity of R² ≈ 0.98. Within 116.9 Hz to 120.8 Hz, the minimum power density is 100 μW/cm³ for a 1 g input excitation level. In mode 100, the sensor voltage sensitivity and power density increase by about 83% and 11%, respectively, compared to a conventional sensor. The self-powered tunable piezoelectric vibration sensor can compensate for physical uncertainty, such as inherent variability in material properties and manufacturing tolerances.