A DOUGHNUT-SHAPED PIEZOELECTRIC ENERGY HARVESTER

Abstract

ABSTRACT A DOUGHNUT-SHAPED PIEZOELECTRIC ENERGY HARVESTER The present invention discloses a novel structure; relates to energy harvesting devices and it will generate micro-energy (energy at micro level), more specifically, a post/pillar can also be utilized to generate micro-energy for powering everyday applications and wearable technologies in biomedical electronic devices, reducing dependency on traditional batteries and helps to environmental sustainability. Figure. 1

Specification

Description:A DOUGHNUT-SHAPED PIEZOELECTRIC ENERGY HARVESTER


FIELD OF INVENTION

The present invention discloses an energy-harvesting device comprising a Doughnut shaped mechanical structure with double serendipity piezoelectric beam etched within the doughnut for energy harvesting. Upon exposure to the physical disturbance, the piezoelectric beams will vibrate, and it will generate micro-energy (energy at micro level). More specifically, the present invention discloses a novel structure including a post/pillar configured to generate micro-energy for powering biomedical electronic devices or applications.

BACKGROUND ART
At present, there is urgent demand for Energy harvesting sources and devices that extract ambient energy from various environments to power electronic devices sustainably. These sources include solar radiation, thermal gradients, vibration, and kinetic motion. And devices working on these renewable sources to convert the energy forms into usable electrical power are used in applications such as wireless sensor networks, wearable electronics, remote monitoring systems, IoT devices and biomedical electronics. They are offering solutions for powering devices in remote locations or where traditional power sources are impractical. Energy harvesting holds promise for reducing reliance on batteries and extending the lifespan of autonomous electronic systems, contributing to a more sustainable future.
The piezoelectric-based energy harvesting devices comprises materials that produces voltage at micro level when subjected to mechanical strain. The vibration of the surrounding environment makes the piezoelectric beam resonate, resulting in mechanical strain and this strain energy is converted into electrical energy.
Cantilever-shaped piezoelectric harvesters are popular due to their simplicity in converting vibrational energy. This invention helps to improve the efficiency and applicability of such devices through innovative design and material enhancements.
In the prior art, an US specification US20170215008 discloses a multi-directional high efficiency piezoelectric energy transducer. This design efficiently captures multi-directional low-frequency vibrations, making it suitable for implantable devices, wearable electronics, and wireless sensor networks.
In another prior art an US specification US20110109203 discloses a flexible piezoelectric structure featuring a high piezoelectric coefficient film attached to a flexible substrate having title Flexible piezoelectric structures and method of making same. This design efficiently suitable for providing energy at micro level for wearable devices.
In another prior art an Indian specification INA202311086375 energy harvesting system integrated into a shoe or footwear using a piezoelectric transducer to capture energy from mechanical stress and heat. The system combines piezoelectric and thermoelectric techniques, enabling simultaneous energy harvesting from both sources.
In another prior art a PCT application WO2012011797 discloses a Piezoelectric energy harvester apparatus designed with a hollow cylindrical structure containing a piezoelectric cantilever bridge. When rainwater from a roof enters the structure, it causes the cantilever to vibrate due to buoyant force, generating micro energy. This energy can power low-power devices, like those used in precision agriculture. Additionally, it serves as an alternative energy source during the rainy season when sunlight is unavailable.
In yet another prior art a Chinese application CN105186922A, discloses a piezoelectric triboelectric MEMS wideband-energy harvester and its preparation method. The harvester includes a silicon-based piezoelectric cantilever beam with a fixed silicon base, piezoelectric thick film, and integrated silicon mass with a frictional layer. This harvester achieves high output power in low-frequency environments, solving traditional MEMS harvester limitations.

OBJECT OF INVENTION:
The principle object of the present invention is to provide a doughnut-shaped piezoelectric energy harvester to harvest mechanical energy from ambient vibrations.
In another object, the said doughnut-shaped structure ensures that vibrations are uniformly distributed to the cantilever beams where under condition when the cantilever beams vibrate, the piezoelectric material generates an electric potential due to the mechanical stress applied by the vibrations.
As per another object of the present invention the seismic mass optimizes the vibration frequency, aligning it with the natural resonant frequency of the cantilever beams, thus maximizing energy output.

SUMMARY OF INVENTION:
Therefore, to justify the demand for energy harvesting devices that extract ambient energy from physical environment, a doughnut structure piezoelectric energy harvesting device is presented with optimized thickness and length ratios having double serendipity cantilever beam etched in doughnut shaped mechanical structure to achieve resonant frequencies that match common environmental vibrations. The introduction of a composite piezoelectric material that combines high piezoelectric coefficient ceramics with flexible polymers, ensuring durability and enhanced energy conversion. The cantilever beams have specific dimensions and are designed to enhance energy conversion efficiency. A seismic mass is attached to the beams to optimize the resonance frequency and maximize the gathered energy.
The performance of the energy harvester as double piezoelectric beam has been examined in relation to frequency response alterations and the load resistance significantly impacts the harvested power level that offer the potential to harvest energy efficiently at low frequencies, outperforming conventional harvesters.
Substrate and Seismic Mass: Made of a flexible substrate material like Brass, structural steel, silicon etc. It provides strength and stiffness which helps in mechanical integrity of the piezoelectric layer. Brass also having good coefficient of thermal expansion, good conductor of electricity and good corrosion resistance which makes it suitable for moisture environment applications. The beam's dimensions are carefully chosen to match the frequency of ambient vibrations.
Piezoelectric Layer: Materials like PVDF, PZT, and Lithium Niobate etc. are versatile material with a balanced combination of mechanical strength, chemical resistance, electrical properties, non-reactive and pure thermoplastic materials.
Electrodes: Thin metal electrode layer (silver, Gold, copper etc.) in ring shaped attached on the surface of the piezoelectric layer to collect generated charges. They are having excellent electrical and thermal conductivity.
In an embodiment, there is provided an energy-harvesting device comprising a doughnut shaped mechanical structure having 20 mm as diameter, characterized by double serendipity piezoelectric beams etched within the doughnut, each beam having dimensions of 15 mm 2.5 mm and 1 mm. There is a creation of self-enable systems and allows centralised energy generation at micro level. It suggests the potential for self-energy generation without dependent on centralized power grids, making it worthy for applications in remote areas or medical electronics.
In another embodiment, there is provided a cuboid seismic mass is attached to the free end of each piezoelectric beam, the seismic mass having dimensions 2 mm 2 mm and 1 mm. The cantilever beams are made of piezoelectric materials like PVDF, PZT, Lithium Niobate etc. and the seismic mass is made of brass.
As per another embodiment, the said energy-harvesting device is configured to optimize energy conversion by tuning the resonant frequency of the cantilever beams through the addition of the seismic mass. This overcomes the dependency of conventional energy sources and extract the voltage when subjected to a frequency range from 100 Hz to 600 Hz.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES:

Figure 1 illustrates an upper view in X-Y Axis of the doughnut-shaped mechanical structure with double serendipity cantilever having seismic mass in accordance with the present invention;
Figure 2 illustrates Side view in Y-X Axis of the proposed model having seismic mass in accordance with the present invention;
Figure 3 illustrates Side view in X-Z Axis of the proposed model having seismic mass in accordance with the present invention;
Figure 4 illustrates Front view in X-Z-Y Axis of the proposed model mentioning the acrylic plastic part in accordance with the present invention;
Figure 5 illustrates an upper view in X-Z-Y Axis of the proposed model mentioning the Brass material part (substrate and seismic mass) in accordance with the present invention; Figure 6 illustrates Top view in X-Z-Y Axis of the proposed model mentioning the piezoelectric material part in accordance with the present invention;
Figure 7 illustrates an upper view in X-Z-Y Axis of the proposed model mentioning the
Electrode (Silver material) part in accordance with the present invention;
Figure 8 illustrates a Bottom view in X-Z-Y Axis of the proposed model mentioning the Electrode (Silver material) part in accordance with the present invention;
Figure 9 illustrates Side view in Y-Z-X Axis of the proposed model mentioning the Piezoelectric material part in accordance with the present invention;
Figure 10 illustrates Top view in Y-Z-X Axis of the proposed model mentioning the terminal part in accordance with the present invention;
Figure 11 illustrates Top view in Y-Z-X Axis of the Meshing of proposed model in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION WITH FIGURES:

The present invention discloses a novel structure; relates to energy harvesting devices and it will generate micro-energy (energy at micro level). More specifically, a post/pillar can also be utilized to generate micro-energy for powering everyday applications and wearable technologies in biomedical electronic devices, reducing dependency on traditional batteries and helps to environmental sustainability.
The Figure 1 depicts an overhead (X-Y axis) view of a unique mechanical design comprising a doughnut-shaped structure featuring a double serendipity cantilever with an attached seismic mass. The doughnut shape provides a circular framework that supports the cantilevers. These cantilevers, positioned within the central cavity of the doughnut for precise response and stability under mechanical stress. This configuration is advantageous for energy harvesting and sensing applications, as it maximizes the mechanical efficiency and electrical output within a compact design.
Figure 2 and Figure 3 are schematic diagram showing a side view in Y-X axis and X-Z axis of the proposed model having seismic mass. The seismic mass, typically located at the free end of the cantilevers, plays a crucial role by enhancing the device's sensitivity to vibrations or forces. As the mechanical pressure is applied on the cantilevers, it induces stress and strain within the cantilevers, generating an electrical response due to the piezoelectric effect.
Figure 4 presents a front view (X-Z-Y axis) of the proposed mechanical structure, focusing on the integration of acrylic plastic components within the model. The structure is characterized by its doughnut-shaped frame, which serves as the mechanical support and insulation to the overall design.
Figure 5 and Figure 6 illustrates a top view (X-Z-Y axis) of the proposed doughnut-shaped mechanical structure, highlighting the integration of the acrylic plastic and piezoelectric material. This model features piezoelectric elements strategically positioned within the central cavity of the doughnut shape, specifically on the double serendipity cantilevers
Figure 7 and Figure 8 provides an upper view (X-Z-Y axis) lower view of the proposed mechanical structure, emphasizing the integration of silver electrodes. This model showcases a doughnut-shaped framework, with silver electrodes strategically placed within the structure.
Figure 9 illustrates the side view in Y-Z-X Axis of the proposed model mentioning the Piezoelectric material part.
Figure 10 provides a top view (Y-Z-X axis) of the proposed doughnut-shaped mechanical structure, highlighting the terminal part of the system. This view focuses on the layout and positioning of the terminal for connecting external circuitry to the device.

Figure 11 illustrates a top view (Y-Z-X axis) of the meshing applied to the proposed doughnut-shaped mechanical structure. The mesh is shown covering the entire model, including the doughnut-shaped frame, the cantilevers, and the integrated components like the piezoelectric material and terminals.
When a piezoelectric energy harvester resonates with an ambient vibration source, it achieves its highest displacement, which in turn maximizes the voltage produced. This phenomenon significantly enhances the efficiency of converting mechanical energy into electrical energy, a critical factor for energy harvesting applications. The key to achieving this resonance lies in aligning the natural frequency of the piezoelectric energy harvester with the frequency of the ambient vibrations.
To ensure this alignment, the natural frequency of the harvester must be precisely tuned to match the frequency of the ambient source. This tuning is heavily influenced by the dimensions of the harvester, including its length, width, and thickness. These geometric parameters play a crucial role in determining the natural frequency, which can be calculated using established equations in mechanical and materials engineering.
V(F)=(3/2)(1-α^2/h^2 )(L/wh)d_31 F (1)
f_r=((0.16h)/L^2 )〖(E/ρ)〗^(1/2) (2)

Wherein, "V(F)" indicates the voltage output from the serendipity piezoelectric beam, "F" indicates the force applied to the piezoelectric beam, "α" represents thickness of the centre shim, "h" indicates total length of piezoelectric beam, "w" indicates the width of the beam, " " represents piezoelectric transverse voltage coefficient, "E" average Young's modulus of elasticity and "ρ" indicates average density of the beam. Equation (2) shows that the natural frequency is inversely related to beam length and the density of the beam.

Inventive step
The described energy-harvesting device offers a novel approach to capturing ambient mechanical vibrations and converting them into usable electrical energy. The innovative design of the doughnut-shaped structure, coupled with the double serendipity piezoelectric beams and optimized seismic mass, ensures high efficiency and robustness, that makes it suitable for various applications in wireless sensors and autonomous devices.
The present innovative design for PEH which achieved the movement ranging from 4 μm to 115 μm, when subjected to a frequency range from 100 Hz to 600 Hz and an acceleration of 1g and the stress calculated in the piezoelectric layer varies from 9.6e+05 N/m² to
5.98e+06 N/m², and produced voltage ranging from 1 V to 20 V.
Although the field of the invention has been described herein with limited reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention.
Reference:
Zhengbao YangJean W. Zu, "Multi-directional high-efficiency piezoelectric energy transducer", US20170215008A9, 2014.
Michael C. McAlpineYi Qi, "Flexible piezoelectric structures and method of making same", US20110109203A1, 2012.
Sahil kumar, Saikat Chakraborty, Abhishek Kumar Mourya, Shubham singh et al., "Energy Harvesting system using piezoelectric transducer", INA 202311086375, 2024.
Shaharia Bhuyan MohammadZainuddin Khairul-HakiminTaher et al., "Piezoelectric based energy harvester", WO2012011797A1, 2011.
Nanchang Institute of Technology, China, " Piezoelectric-triboelectric combined MEMS wideband-energy harvester and preparation method thereof", CN105186922A, 2015.
, Claims: WE CLAIM:

1. A doughnut-shaped piezoelectric energy harvester comprising of:
a doughnut-shaped mechanical structure featuring a double serendipity cantilever with an attached seismic mass;
a plurality of cantilevers made of piezoelectric material disposed within the central cavity of the said doughnut for precise response and stability under mechanical stress including connecting electrodes;
a seismic mass is attached to the said beams configured to optimize the resonance frequency and maximize the gathered energy.
wherein said doughnut shape provides a circular framework that supports the said cantilevers; and
wherein said doughnut structure piezoelectric energy harvesting device is presented with optimized thickness and length ratios having double serendipity cantilever beam etched in doughnut shaped mechanical structure achieving resonant frequencies that match common environmental vibrations as it maximizes the mechanical efficiency and electrical output.

2. The doughnut-shaped piezoelectric energy harvester as claimed in claim 1, wherein said doughnut-shaped mechanical structure is 20 mm as diameter, with double serendipity piezoelectric beams etched within the doughnut, each beam having dimensions of 15 mm
2.5 mm and 1 mm.

3. The doughnut-shaped piezoelectric energy harvester as claimed in claim 1, wherein a cuboid seismic mass is attached to the free end of each piezoelectric beam, the seismic mass having dimensions 2 mm 2 mm and 1 mm.

4. The doughnut-shaped piezoelectric energy harvester as claimed in claim 1, wherein said cantilever beams are made of piezoelectric materials like PVDF, PZT, Lithium Niobate and the like.

5. The doughnut-shaped piezoelectric energy harvester as claimed in claim 1, wherein seismic mass is made of brass, structural steel, silicon and the like.

6. The doughnut-shaped piezoelectric energy harvester as claimed in claim 1, wherein said energy-harvesting device is configured to optimize energy conversion by tuning the resonant frequency of the cantilever beams through the addition of the seismic mass.

7. The doughnut-shaped piezoelectric energy harvester as claimed in claim 1, wherein said harvester is configured to overcome the dependency of conventional energy sources and extract the voltage when subjected to a frequency range from 100 Hz to 600 Hz.

8. The doughnut-shaped piezoelectric energy harvester as claimed in claim 1, wherein said electrodes are thin metal layer (silver, Gold, copper etc.) in ring shaped attached on the surface of the piezoelectric layer to collect generated charges with high electrical and thermal conductivity.

9. The doughnut-shaped piezoelectric energy harvester as claimed in claim 1, wherein said doughnut-shaped mechanical structure, highlight the integration of the acrylic plastic and piezoelectric material; and wherein said piezoelectric elements are strategically positioned within the central cavity of the said doughnut shape, specifically on the double serendipity cantilevers.

10. The doughnut-shaped piezoelectric energy harvester as claimed in claim 1, wherein, said harvester is configured to generate micro-energy for powering everyday applications and wearable technologies in biomedical electronic devices, reducing dependency on traditional batteries and helps to environmental sustainability.

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