PMUT Array EMI Shielding via Conductive Layer
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Solution Overview
Problem
Piezoelectric micromachined ultrasound transducer (PMUT) devices are susceptible to electromagnetic interference (EMI), which can disrupt their operation and reduce the accuracy of biometric readings such as fingerprint sensing.
Innovation Solution
Incorporating a conductive layer or EMI shielding mesh that provides a path to ground for incoming EMI, reducing interference by electrically connecting it to the PMUT devices' electrodes and structural layers, thereby shielding the active components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PMUT devices are designed with complex configurations for multiple applications, then the functionality and versatility of the device is improved, but the susceptibility to electromagnetic interference increases
Solution Approach 1:
A conductive shielding layer is introduced as an intermediary element between the PMUT devices and the external electromagnetic environment. This shielding layer acts as a mediator that intercepts and redirects EMI away from the sensitive piezoelectric materials and electrodes, thereby protecting the device functionality while maintaining its versatility for multiple applications
2Adaptability or versatility
If the PMUT array is used in complex environmental conditions, then the application range is expanded, but the operational reliability decreases due to EMI
Solution Approach 1:
The conductive shielding layer is configured in advance to counteract electromagnetic interference before it can affect the PMUT devices. By establishing this protective barrier beforehand, the device maintains operational reliability when deployed in complex environmental conditions across various applications
3Object-affected harmful factors
If EMI shielding is added to PMUT devices, then the protection against electromagnetic interference is improved, but the device complexity increases
Solution Approach 1:
The conductive shielding layer is designed to serve multiple functions simultaneously: it provides EMI protection, maintains structural integrity of the PMUT array, and can be integrated with existing electrical connections. This multi-functionality approach adds protection while minimizing the increase in overall device complexity
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 EMI shielding effectively reduces electromagnetic interference, enhancing the operational reliability and accuracy of PMUT devices in complex environments by directing unwanted signals to ground, thus minimizing their impact on the transducers.
Implementation Method 1
The PMUT device may include a piezoelectric material that provides an electro-mechanical response based on a given input signal. For example, when an electrical signal is applied to the piezoelectric material, the material may exhibit a mechanical response. In response to a received mechanical signal, the piezoelectric material may exhibit an electrical response.
Implementation Method 2
Incorporating a conductive layer or EMI shielding mesh that provides a path to ground for incoming EMI, reducing interference by electrically connecting it to the PMUT devices' electrodes and structural layers, thereby shielding the active components.
Data Source
AI summary
A piezoelectric micromachined ultrasound transducer (PMUT) array may comprise PMUT devices with respective piezoelectric layers and electrode layers. Parasitic capacitance can be reduced when an electrode layer is not shared across PMUT devices but may expose the devices to electromagnetic interference (EMI). A conductive layer located within the structural layer or on a shared plane with the electrode layers may reduce EMI affecting the PMUT array operation.