Theoretical analysis of the sensor effect of cantilever piezoelectric benders

Abstract

Piezoelectric bending mode elements such as bimorph and unimorph benders can be used as both actuation and sensing elements for a wide range of applications. As actuation elements, these devices convert electric input energy into output mechanical energy. As sensing elements, they convert external mechanical stimuli into electrical charge or voltage. In this article, the sensing effect of cantilever mounted piezoelectric bimorph unimorph and triple layer benders subjected to external mechanical excitations are discussed. General analytical expressions relating generated electric voltage (or charge) to the applied mechanical input excitations (moment M, tip force F, and body force p) are derived based on the constitutive equations of these bending devices. It is found that the clamping effect of each component in the bender devices decreases the dielectric constant. The bimorph bender has a higher voltage sensitivity than the unimorph or triple layer bender with the same geometrical dimensions. The dependence of voltage and charge sensitivities on the thickness ratio and the Young’s modulus ratio of the elastic layer and piezoelectric layer under different conditions are discussed and compared for the unimorph and triple layer benders.

Sensitivity of Micro Cantilever Mass Sensor Transduced by PZT Film

“…It's clear that the cantilever width b will decreases at the cost of lower piezoelectric charge output Q (t). On the other hand, the decrease of cantilever length L will reduce the tip displacement δ (t) notably because δ (t) is proportional to L 3 for a given excitation force F (19) . This is what we have to consider during device design and optimization.…”

“…According to the basic constituent equations of bimorphs (18) (19) , when we fix the thickness of the structural layer t e as did in this paper, the piezoelectric induced charge Q (t) and open circuit voltage V (t) for a given cantilever tip displacement δ (t) are: k is the electromechanical coupling coefficient of the PZT film, e E is the Young's modulus of the structural layer and p E is the Young's modulus of the PZT film. It's clear that the cantilever width b will decreases at the cost of lower piezoelectric charge output Q (t).…”

Energy recovery power supply for piezoelectric actuator

“…Different piezoelectric actuators were available: thick PZT (Ferroperm Piezoceramics), PZT fibers composite (Smart Material) and Thunder® (Face International). There were already several comparative studies of these actuators [11][12][13][14]. Due to the clamped capacitance, the piezoelectric devices are absorbing reactive energy.…”

Thermally activated paraffin-filled McKibben muscles

“…Artificial muscles are of interest for assisting human movement in cases of injury/disability or for use in robotics and medical devices (Gordon et al, 2006;Tarnita et al, 2009;Villegas et al, 2012;Tommasino et al, 2012). Artificial muscles normally offer three different types of actuation movements: torsional (Foroughi et al, 2011), tensile (Hunter and Lafontaine, 1992) and bending (Wang et al, 1999). Tensile contractile is the most common movement in skeletal muscle in humans and animals, allowing complex and agile movements as in jumping and lifting (Josephson, 1993).…”