Measured Output Voltages of Piezoelectric Devices Depend on the Resistance of Voltmeter

Abstract

Piezoelectric mechanical energy harvester (MEH) has been developed as an important emerging variant of piezoelectric devices. Experiments in the literature show that the voltage–time curves of piezoelectric devices encompass both positive and negative characteristics even though the strain in the piezoelectric material is always positive during the applied cycling load. This does not agree with the results predicted by the piezoelectric theory of open circuit. Here, both the experiments and theory are performed to understand this important problem. A zirconate titanate (PZT) MEH is fabricated and the output voltages are recorded with three voltmeters. It is found that the measured voltages depend on the resistance of voltmeter. The peak value of voltage increases with the increase of the resistance of voltmeter, which is contrary to the established knowledge that the measurement results are independent of the instruments used. A theoretical model considering the voltmeter with finite resistance is established. The charge is allowed to go through the voltmeter and switch the directions during increasing and releasing of strain. The results by this model agree well with those from the experiments. The findings suggest that the resistance of voltmeter should be reported for voltage measurement of the piezoelectric devices.

Shear deformation dominates in the soft adhesive layers of the laminated structure of flexible electronics

“…Due to the favorable properties, many emerging flexible electronic applications and their variants with the stretchability have been developed such as stretchable and foldable silicon integrated circuits ( Kim et al, 2008;Li et al, 2013b ), electronic eye cameras ( Ko et al, 2008;Song et al, 2013 ), epidermal electronics ( Kim et al, 2011 ), fingertip electronics Ying et al, 2012 ), transient electronics ( Hwang et al, 2012;Li et al, 2013a ), stretchable batteries and conformal piezoelectric energy harvesters ( Dagdeviren et al, 2014;Su et al, 2015a ). There is a critical mechanics issue in the design of a laminated structure of flexible electronics, i.e., how to stack the hard layers, where the brittle component is placed, in order that the entire electronic device exhibits the best performance while premature mechanical failure is avoided in repeated bending in use.…”

A Traction-Free Model for the Tensile Stiffness and Bending Stiffness of Laminated Ribbons of Flexible Electronics

“…For the bending stiffness, a uniformly distributed bending moment z m is applied to the two ends of the ribbon while other forces and moments are zero (Fig. 2a) Moreover, the result of the traction-free model is closer to that of the plane-stress model, instead of the plane-strain model that has been usually adopted in the past mechanical analysis for simplicity [14,15].  is studied in Fig.…”

“…Flexible electronics have attracted increasing interest in the last decade due to its great potential applications [1,2]. Examples include electronic eye cameras [3], stretchable electronic skin [4][5][6], flexible health monitoring system [7][8][9][10], stretchable batteries [11], multifunctional integumentary cardiac membranes [12,13], piezoelectric energy harvesters [14][15][16][17][18], smart gloves for gesture recognition and smart clothing for sitting posture monitoring [19]. More and more studies turn to practical applications [19][20][21] from ideal concepts of flexible electronics [22][23][24][25][26][27].…”

“…These laminated ribbons usually are subjected to loads of tension and bending. Their effective tensile stiffness and bending stiffness, which are frequently used as fundamental parameters in the mechanical analysis, are usually obtained by the plane-strain hypothesis [14,15,17,[40][41][42][43][44][45].…”

Piezoelectric Buckled Beam Array on a Pacemaker Lead for Energy Harvesting

“…As discussed in the literature, the voltage output from a piezoelectric buckled beam was proportional to the change of local curvature. In our FEM simulations, the local curvature showed significant changes at different configurations.…”