Self-Biased Piezoelectric-Piezoresistive Sensor for Energy Harvesting
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Solution Overview
Problem
Current sensing devices face challenges in efficiently harnessing ambient vibrations to power themselves without external energy sources, particularly in generating high-quality sensory data in a cost-effective and durable manner using accessible probing systems.
Innovation Solution
A self-biased sensing device is developed, incorporating a vertical integration structure with a piezoelectric thin film layer and a piezoresistive thin film layer, where the gate electrode regulates charge flow in response to strain, allowing for energy harvesting and storage without an external power source, and includes interdigitated or fractal metallization structures for enhanced current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If piezoelectric and piezoresistive materials are used in micro-harvesters, then energy harvesting capability is improved, but device complexity increases
Solution Approach 1:
The patent combines piezoelectric and piezoresistive materials into a single integrated micro-harvester device, merging two separate sensing mechanisms into one unified structure that can both harvest energy and sense pressure simultaneously
Solution Approach 2:
The micro-harvester device is designed to perform multiple functions: energy harvesting from ambient vibrations, pressure sensing, and electrical signal generation, eliminating the need for separate devices and reducing overall system complexity
2Ease of operation
If external power sources are used to manipulate piezoelectric material, then electrical control capability is improved, but energy independence deteriorates
Solution Approach 1:
The device generates its own electrical power through the piezoelectric effect by harvesting mechanical energy from ambient vibrations, eliminating the need for external power sources and achieving self-powered operation
Solution Approach 2:
The piezoelectric material is subjected to periodic mechanical stress from ambient vibrations, generating electrical signals through repeated cycles of mechanical-to-electrical energy conversion
3Measurement precision
If capacitive sensing mechanisms are used, then sensor sensitivity is improved, but output signal strength deteriorates
Solution Approach 1:
The device uses a composite structure combining piezoelectric and piezoresistive materials, where the piezoresistive component provides strong output signals while the piezoelectric component enables energy harvesting and sensitive pressure detection
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
The device generates sufficient output current and voltage from mechanical stress, enabling self-operation and long-term monitoring applications, such as cardiac activity monitoring, with improved sensitivity and reduced energy consumption.
Implementation Method 1
The upper harvester has a piezoelectric thin film layer... the piezoelectric thin film layer of the upper harvester is in a plane substantially perpendicular to a direction of the applied stress on the sensor
Implementation Method 2
a piezoresistive thin film layer for providing a channel region permitting passage of charge carriers between the source region and the drain region
Data Source
AI summary
A sensing device, a method for fabrication thereof, and a method for operating the same are disclosed. The sensing device includes an upper harvester having a piezoelectric (PE) thin film layer, a pressure sensor having a first metallization layer forming a source region and a drain region, a piezoresistive (PR) thin film layer that provides a channel region permitting passage of charge carriers between the source region and the drain region, a second metallization layer forming a gate electrode and regulating flow of the charge carriers through the piezoelectric thin film layer in response to a strain on the PE thin film layer, and an insulating layer disposed between the PR thin film layer and the second metallization layer. In other embodiments, the device includes a lower harvesting including a PE thin film layer for harvesting electrical energy from the stress of a mechanical load on the device.