Enhancing the Bandwidth and Energy Production of Piezoelectric Energy Harvester Using Novel Multimode Bent Branched Beam Design for Human Motion Application

Abstract

In recent years, harvesting energy from ubiquitous ultralow-frequency vibration sources, such as biomechanical motions using piezoelectric materials to power wearable devices and wireless sensors (e.g., personalized assistive tools for monitoring human locomotion and physiological signals), has drawn considerable interest from the renewable energy research community. Conventional linear piezoelectric energy harvesters (PEHs) generally consist of a cantilever beam with a piezoelectric patch and a proof mass, and they are often inefficient in such practical applications due to their narrow operating bandwidth and low voltage generation. Multimodal harvesters with multiple resonances appear to be a viable solution, but most of the previously proposed designs are unsuitable for ultralow-frequency vibration. This study investigated a novel multimode design, which included a bent branched beam harvester (BBBH) to enhance PEHs’ bandwidth output voltage and output power for ultralow-frequency applications. The study was conducted using finite element method (FEM) analysis to optimize the geometrical design of the BBBH on the basis of the targeted frequency spectrum of human motion. The selected design was then experimentally studied using a mechanical shaker and human motion as excitation sources. The performance was also compared to the previously proposed V-shaped bent beam harvester (VBH) and conventional cantilever beam harvester (CBH) designs. The results prove that the proposed BBBH could harness considerably higher output voltages and power with lower idle time. Its operating bandwidth was also remarkably widened as it achieved three close resonances in the ultralow-frequency range. It was concluded that the proposed BBBH outperformed the conventional counterparts when used to harvest energy from ultralow-frequency sources, such as human motion.

Development of 2400–2450 MHz Frequency Band RF Energy Harvesting System for Low-Power Device Operation

“…where L is the length of the patch, f is the operating frequency, c represents the speed of light, W is the width of the patch, h is the height of the substrate, and ε e f represents effective dielectric constant, which can be computed using Equation (3).…”

“…where L is the length of the patch, f is the operating frequency, c represents the speed of light, W is the width of the patch, h is the height of the substrate, and 𝜀 represents effective dielectric constant, which can be computed using Equation (3). The design of the inset aimed to establish the input impedance when looking at the edge of the patch to a predetermined target impedance.…”

“…Consequently, portable devices have assumed a pivotal role in crucial sectors, such as medical applications, security, communication, and industrial systems monitoring [1]. In situations where devices must be deployed in remote or difficult-to-access areas, making battery reinstatement and maintenance impractical, a successful approach involves the adoption of renewable energy harvesting [2,3]. This approach aims to eliminate the reliance on batteries or enhance the battery's life cycle.…”

Linear Segmented Arc-Shaped Piezoelectric Branch Beam Energy Harvester for Ultra-Low Frequency Vibrations

“…The design performed better in power density than the conventional PEH since a single piezoelectric patch was used to generate multiple resonance peaks. Further studies on the branch beam concept were conducted by Upadrashta et al [30], Izadgoshasb et al [31] and Piyarathna et al [32]. Even though the devices mentioned above were superior to the conventional PEH, they either carried excessive proof masses for performance improvement, were not satisfying for multi-directional ultra-low frequency vibrations, such as human motion, or had limited performance improvement in an ultra-low frequency range.…”