Piezoelectric-transducer energy harvester, in particular for powering an autonomous cardiac capsule, with a bending stiffness gradient oscillating structure
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Solution Overview
Problem
The challenge is to simplify the architecture of Piezoelectric Energy Harvesters (PEH) and corresponding implantable medical devices, while reducing the volume occupied by the pendular unit and associated components, and optimizing the mechanical characteristics of the oscillating beam to enhance performance and reduce manufacturing costs.
Innovation Solution
The proposed solution involves a piezoelectric-transducer energy harvester with a pendular unit that includes a flexible piezoelectric beam with a semiconductor central core, integrated electronic components such as a power management unit and energy storage elements, and a method of manufacturing that forms a bending stiffness gradient along the beam to optimize energy conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a conventional battery is used to power implantable medical devices, then the device can operate for extended periods, but the device volume becomes too large for miniaturization requirements
Solution Approach 1:
The patent combines the energy harvesting function and energy storage function into a single integrated structure. The piezoelectric beam serves both as the oscillating element for energy harvesting and as the structural support for the battery, eliminating the need for separate mounting components and reducing overall device volume while enabling extended operation through continuous energy harvesting from cardiac movements
Solution Approach 2:
The piezoelectric beam performs multiple functions simultaneously: it acts as the oscillating mass for mechanical energy harvesting, provides structural support for the battery, and converts mechanical energy to electrical energy through piezoelectric effect. This multi-functionality reduces the number of separate components needed, enabling device miniaturization while maintaining extended operational duration
2Volume of moving object
If the pendular unit volume is reduced for miniaturization, then the device becomes more compact, but the energy harvesting performance deteriorates
Solution Approach 1:
By merging the battery mounting function into the piezoelectric beam structure itself, the patent eliminates additional volume-consuming components. The battery is positioned to utilize the beam's structural volume, allowing the pendular unit to maintain adequate mass and dimensions for effective energy harvesting while achieving compact overall device volume suitable for implantation
3Ease of manufacture
If the beam structure is simplified for easier manufacturing, then production costs decrease, but the mechanical characteristics and energy conversion efficiency are compromised
Solution Approach 1:
The patent integrates battery mounting features directly into the piezoelectric beam structure, such as recesses or attachment points formed during beam fabrication. This approach simplifies manufacturing by combining multiple components into one structural element while maintaining the beam's mechanical properties and piezoelectric performance through standard fabrication processes
Solution Approach 2:
The beam structure incorporates localized features for battery mounting only where needed, without compromising the overall beam integrity or piezoelectric performance. The mounting features are strategically positioned to minimize impact on the beam's oscillation characteristics and energy conversion efficiency while providing adequate support for the battery
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the overall volume of the system, improves performance by integrating multiple functions into a single structure, and simplifies industrialization and manufacturing processes, while maintaining the efficiency of energy harvesting and powering implantable medical devices.
Implementation Method 1
a beam which is piezoelectric and adapted to convert into an oscillating electric signal a mechanical energy produced by oscillations of the pendular unit
Data Source
AI summary
The harvester comprises a pendular unit comprising a beam that is elastically deformable in bending, a mount clamping a proximal end of the beam, and an inertial mass mounted at a free, distal end of the beam. The beam converts into an oscillating electric signal a mechanical energy produced by pendular unit oscillations. The beam comprises a flexible structure including a central core, a piezoelectric layer on at least one face of the central core, and at least one surface electrode on an external face of the piezoelectric layer. The central core of the flexible structure is made of a semiconductor material adapted to form an integrated circuit substrate. The substrate made of a semiconductor material of the central core includes monolithic integrated structures, and the arrangement, over the extend of the central core substrate, of said integrated structures forms in the longitudinal direction a plurality of successive areas having different bending stiffness coefficients from an area to another.