Flexible Piezoelectric Sensor With Integrated Thin-Film EMI Shielding
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Solution Overview
Problem
Existing flexible piezoelectric sensors face challenges in effectively shielding against electromagnetic interference and capacitive coupling noise, which degrade signal quality due to their integration with wearable electronic devices, necessitating a lightweight and flexible electromagnetic shield solution.
Innovation Solution
A flexible piezoelectric sensor design integrates a short-circuited metal layer as an electromagnetic shield within a polymeric matrix, using standard microfabrication techniques, ensuring mechanical flexibility and signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional metal electromagnetic shields are used, then electromagnetic shielding effectiveness is improved, but device weight increases
Solution Approach 1:
The patent employs thin metal films (aluminum, copper, or silver) with thickness of 10-100 nm deposited as additional layers on the flexible substrate, replacing traditional bulk metal shields. These thin films provide effective electromagnetic shielding while maintaining device flexibility and significantly reducing weight compared to conventional metal shields.
Solution Approach 2:
The patent creates a composite structure combining flexible polymeric substrate with thin metal shielding layers and piezoelectric active layers. This composite approach integrates multiple functions (flexibility, electromagnetic shielding, sensing) into a single lightweight structure, eliminating the need for separate heavy metal shield components.
2Object-affected harmful factors
If metal layers are added for electromagnetic shielding, then shielding effectiveness is improved, but device flexibility deteriorates
Solution Approach 1:
The patent uses extremely thin metal films (10-100 nm) deposited on flexible polymeric substrates, which maintain the overall flexibility of the device. The thin film structure provides electromagnetic shielding without creating rigid structures that would compromise device bendability and conformability to skin surfaces.
Solution Approach 2:
The patent changes the thickness parameter of metal shielding layers from conventional micrometer-scale to nanometer-scale (10-100 nm), which fundamentally alters the mechanical properties while preserving electromagnetic shielding effectiveness. This parameter change enables the shield to be flexible and conformable rather than rigid.
3Measurement precision
If sensor thickness is reduced to capture minimal skin deformation, then sensitivity to micro-deformations is improved, but signal quality deteriorates due to noise
Solution Approach 1:
The patent encapsulates the piezoelectric sensor in thin flexible polymeric layers and adds thin metal shielding films, creating a protected yet flexible structure. This thin-film encapsulation and shielding system reduces noise from electromagnetic interference and capacitive coupling while preserving the sensor's ability to detect minimal skin deformations.
Solution Approach 2:
The patent introduces thin polymeric encapsulation layers and metal shielding films as intermediary structures between the piezoelectric active layer and the external environment. These intermediaries filter out electromagnetic noise and capacitive coupling effects while allowing mechanical deformations to be transmitted to the sensor for accurate measurement.
4Object-affected harmful factors
If integrated electromagnetic shielding is implemented, then noise reduction is improved, but device complexity increases
Solution Approach 1:
The patent merges the electromagnetic shielding function with the sensor structure by depositing metal shielding layers directly onto the flexible substrate during the same manufacturing process as the piezoelectric active layers. This integration eliminates the need for separate shield components and simplifies the overall device structure while providing effective noise reduction.
Solution Approach 2:
The patent designs the metal additional layers to serve multiple functions: electromagnetic shielding, structural encapsulation support, and potential electrical connection pathways. This multi-functionality reduces the need for separate dedicated shield components, thereby reducing device complexity while achieving effective noise reduction.
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 integrated shield significantly reduces electromagnetic and capacitive noise, maintaining signal quality and flexibility, achieving noise rejection comparable to commercial sensors.
Implementation Method 1
active sensors based on piezoelectric materials that directly generate a charge in response to a deformation stimulus
Implementation Method 2
an additional layer of metal material arranged on the coating layer, wherein the additional layer is short-circuited to the bottom electrode, said additional layer and bottom electrode acting as an electromagnetic shield for the sensor
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The disclosed flexible sensor comprises a flexible substrate (10) of polymeric material, a bottom electrode (30) configured as a reference electrode (120), an active layer (40) of piezoelectric material, a top electrode (50) connected to a signal conductor (110), a flexible coating layer (60) of polymeric material which cooperates with the substrate to encapsulate the electrodes and active layer, and an additional layer (70) of metal on the coating layer and short-circuited to the bottom electrode, the additional layer and the bottom electrode acting as an electromagnetic shield.