Design and Implementation of Interface Circuits Intended for Printed Piezoelectric Micropower Harvesters on Flexible Substrates

Abstract

Interface circuits with low power dissipation is proposed and implemented, which is useful for efficient AC/DC voltage conversion of thin-film piezoelectric micro-power stack mounted harvesters. The focus is on low-power (< 1 μW) elements consisting of printed PVDF-TrFE piezoelectric polymer on BaSrTiO3 coated flexible substrate with total thickness of the stack 3.1 μm. Using silver thin films as bottom and top electrodes, the samples exhibited stable piezoelectric rms voltage between 200 mV and 400 mV produced from functional area of ∼1.5 cm2 when stimulates it with sine-wave vibration with frequency of 50 Hz and intensity equivalent to mass loading between 1–80 g. The current registered from a single harvesting element is not greater than 1 μA. For this type of harvesters two power processing circuits intended are designed and built. The first circuit is a voltage doubler, for which the rectified output voltage is approximately equal to twice of the amplitude of the input voltage. The second circuit is a voltage quadrupler; as compared to the first one it provides higher voltage for charging a small and thin-size chip supercapacitor connected to the output port, but due to diodes voltage drops a smaller value of the energy efficiency can be obtained. For the implementation of the electronic circuits, low-power Schottky diodes with a forward voltage below 100 mV at current up to 0.1 mA are chosen. An experimental study to verify the efficiency of the proposed circuits is performed with laboratory made thin-film piezoelectric harvesters.

Analysis of the Methods for Realization of Low-Power Piezoelectric Energy Harvesting Circuits for Wearable Battery-Free Power Supply Devices

“…In cases where a higher output voltage is required, multipliers with a larger multiplication factor are used. Figure 19 shows a circuit diagram of a voltage quadrupler [45,60,61]. Compared to the voltage-doubler circuit, the voltage-quadrupler circuit results in a lower energy efficiency value because it contains a larger number of passive components.…”

“…One of the main trends in the construction of lowpower electronic converters is increasing the output power (>1 mW and mainly providing a larger output current) and simultaneously reducing the power dissipation (≤10 µW). As can be seen in Tables 1 and 2, a higher value for electrical energy efficiency can be achieved by designing the electronic circuits basically using circuit variants of synchronized switch harvesting on inductor (SSHI) [8,[81][82][83][86][87][88][89][90][91][92][93][94], voltage rectifiers employing MOS transistors [53,81,85,87,94] or voltage multipliers with Schottky diodes [7,[59][60][61]84,86], active diodes [82,87,91,93], cold-start-up circuits [8,11,83,89], active and sleep mode of operation [8,81], self-powered circuits from the signal source, and providing a buck/boost DC-DC converter mode of operation [92], as well as a charging control circuit for an energy storage element. An interesting implementation of an electronic circuit for a cold start, which can determine an increase in energy efficiency, is given in [55].…”

Impedance Spectroscopy of Lead-Free Ferroelectric Coatings

“…where R 1 is the serial resistance of L 1 , L 1 is the parallel equivalent inductance and C 1 is the parallel equivalent capacitance. Based on the analysis of Equation (11) and the formulas, the basic parameters for the elements in the equivalent circuit and for the coefficients of the analytical expression of the complex resistance were obtained: k = R 1 = 200 Ω; ξ ≈ 0.01 (or Z max ≈ 850 kΩ); T 2 = 1 2π f p = 27.067 µs;…”

“…In our previous study, we found that printed PVDF-TrFE on BaSrTiO 3 (BST) sputtered film exhibited an excellent performance, and that a composition between them arose due to diffusion of the PVDF-TrFE particles between the crystallites of the BST [11]. This combination was explored for energy harvesting and energy storage applications [12].…”