MEMS Sound Transducer Polymer Structural Layer
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Solution Overview
Problem
There is a need for high-performance MEMS sound transducers that can efficiently generate and/or detect sound waves in the audible and ultrasonic ranges.
Innovation Solution
The MEMS sound transducer incorporates a carrier with a deflectable piezoelectric element, featuring a piezoelectric layer and a structural layer made of polymer, which enhances deflection capabilities. A compensation layer, typically made of metal or silicon dioxide, is used to counteract the contraction of the polymer structural layer, maintaining the piezoelectric element in a tension-free state and optimizing its deflection properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a structural layer made of silicon is used, then the piezoelectric element has high structural integrity, but the deflection capability is limited
Solution Approach 1:
The patent changes the material parameter of the structural layer from silicon to polymer, which has different mechanical properties (higher flexibility, lower modulus of elasticity). This parameter change enables greater deflection capability while maintaining sufficient structural integrity for the application
Solution Approach 2:
The patent creates a composite structure by combining the piezoelectric layer with a polymer structural layer. This composite material approach allows the structural layer to provide both mechanical support and enhanced flexibility, achieving a balance between structural integrity and deflection capability that neither material could provide alone
2Length of moving object
If the piezoelectric element length is shortened, then the device size is reduced, but the deflection capability decreases
Solution Approach 1:
By changing the material parameter of the structural layer to polymer, the patent enables short piezoelectric elements to maintain adequate deflection capability. The polymer's mechanical properties compensate for the reduced length, allowing the element to achieve sufficient deflection despite its compact size
3Length of moving object
If a polymer structural layer is used, then greater deflection is achieved, but mechanical tension causes the layer to contract and deform
Solution Approach 1:
The patent applies a compensation layer that generates mechanical tension in the opposite direction to counterbalance the contraction force of the polymer structural layer. This counterweight approach neutralizes the destabilizing effect, allowing the polymer layer to provide enhanced deflection without suffering from contraction-induced deformation
Solution Approach 2:
The compensation layer is designed to preemptively counteract the contraction tendency of the polymer layer before it can cause deformation. By applying an opposing mechanical tension in advance, the system prevents the harmful effect from manifesting, maintaining the structural layer's shape stability
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 configuration allows for increased deflection capabilities of the piezoelectric element while maintaining its structural integrity, enabling the MEMS sound transducer to operate effectively as both a loudspeaker and a microphone across various sound frequency ranges.
Implementation Method 1
electrical signals and deflections of the piezoelectric element are convertible into one another by means of the at least one piezoelectric layer
Implementation Method 2
the structural layer tends to contract. Due to the properties during production and/or the properties of the polymer, the at least one structural layer can have an internal mechanical tension that tends to contract the structural layer
Data Source
AI summary
In one aspect, a MEMS sound transducer for generating and/or detecting sound waves in the audible wavelength spectrum and/or in the ultrasonic range includes a carrier and at least one piezoelectric element. The at least one piezoelectric element is arranged on the carrier and is deflectable in the direction of a stroke axis. The at least one piezoelectric element has at least one piezoelectric layer and at least one structural layer, wherein electrical signals and deflections of the at least one piezoelectric element are convertible into each other using the at least one piezoelectric layer. Additionally, the at least one structural layer is made of a polymer, with the polymer comprising a polyamide.