Design and optimization of lightweight bending strain energy harvesters using irradiation cross-linked polypropylene ferroelectret

Abstract

In this work, a concept for strain-bending energy harvesting with lightweight ferroelectrets subject to metallic host structures is proposed. The energy harvester (EH) works with the ferroelectret irradiation cross-linked polypropylene (IXPP) and uses the piezoelectric δ33-mod by transferring in-plane strain energy of a host structure to a compression of an IXPP stack. This is achieved with a simple and lightweight transmission made of structural steel. In this way, a high ratio of generated power per used EH mass can be achieved. To demonstrate this, miniature EHs as unit cells for larger EH systems are investigated. The strain magnitude of the excitation in an aircraft wing of 4.5*10^-5 m/m at 1.5 Hz from previous work is partly taken into account for calculations. In an analytical modeling approach, the energy conversion abilities of the presented concept is compared to concepts using PZT ceramics to stress the usefulness in cases where strain energy is the prominent source of vibration energy. Further, an optimization algorithm is presented for a static and a dynamic case without a host structure and for a dynamic case with an aluminum host structure. The optimized power output and power output per total EH mass for the three cases is calculated to 1.52µW and 271µW/kg, 0.7mW and 80mW/kg as well as 6.53µW (at 1N excitation magnitude) and 10.8mW/kg (at 1N excitation magnitude) respectively. Finally, experimental results for case three are presented to validate the model of the proposed and optimized EH topology up to 500Hz. The results further show a good mechanical reproducibility of the measured transfer behaviour and a fairly good reproducibility of the mechanical-electrical results due to deviations in material properties. A comparison of the model with the experimental results shows a good agreement. Therefore a linear ferroelectret model appears to be suitable to predict the system behaviour in lower and higher frequency ranges as well as for high ferroelectret material strains. The optimized EH provides a comparably high ratio of power output per mass when added to a structure like an aircraft which is shown in a comparison to other research works. The performance in a real application can be further improved to 52 mW within a 1m² area using a clustering approach, discussed in the paper. Large deformations of of lightweight structures like aircraft wings at low and high frequencies can thus be exploited to provide enough electrical power decentrally for low-power consumers.

Flexible sensor and energy harvesting technology based on ferroelectret for the acquisition of mechanical and physiological parameters close to the body

“…As expected, an increase in the seismic mass and/or an increase in the acceleration induced by the shaker leads to an increase in the energy generated. [6] Further investigations are part of ongoing research work aimed at optimising the active principle for the planned application in wearables [7]. To this end, new ferroelectrets with modified structures are also being investigated.…”

“…Harvester principle using the 𝑑31-mode [3,4] Which of these different concepts is to be favoured depends on the respective application and its boundary conditions. In principle, concept 2. is more suitable for integration into belts or flat textile structures on which forces act that lead to inplane deformation or applications in which low-frequency vibrations can be used to achieve in-plane deformation of the electret [7]. Concept 1. offers advantages in the realisation of a vibrating system in a higher frequency range.…”

Smart Cushions with Machine Learning-Enhanced Force Sensors for Pressure Injury Risk Assessment

“…The FFS has a planar structure, with the ferroelectret film sandwiched between polydimethylsiloxane (PDMS) layers, and serves as the calibration unit for the FCS, assisting it in determining the direction of the force. Previous studies demonstrate that the irradiated cross-linked polypropylene (IXPP) ferroelectret has the advantages of high piezoelectric activity, excellent flexibility, and easy fabrication. − As a result, the commercial ferroelectret films were made from IXPP resin (DM-PEM00080, Darmu New Materials and Technology Co., Ld., Shanghai, China), which were selected as the key sensing material in the sensor. The optical diagram of the 2D-FS sample is shown in Figure b.…”

Leveraging Ferroelectret Nanogenerators for Acoustic Applications

“…To date, FENGs have enabled intriguing advances in energy harvesting [24,25], robotics [26], biomechanical monitoring [27], etc. Moreira et al [19] provided a brief introduction to FENG.…”