CMUT Transducer Manufacturing with Segmented Conductive Layers
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Solution Overview
Problem
Conventional CMUT transducers are limited in simultaneously manufacturing transducers with different ultrasound frequencies on the same substrate, as their resonance frequencies are fixed by geometric and mechanical characteristics, making it difficult to achieve multifrequency operation.
Innovation Solution
The method involves forming cavities and flexible membranes on a substrate, with specific electrically-conductive layers extending over portions of the membranes to create transducers with distinct resonance frequencies, allowing for simultaneous manufacturing of CMUT transducers with different frequencies on the same substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional CMUT transducer manufacturing is used, then transducers with fixed resonance frequencies are produced, but the ability to manufacture multifrequency transducers on the same substrate is limited
Solution Approach 1:
The patent applies local quality by forming a first electrically-conductive layer that extends over only a portion of the membrane surface, creating regions with different electrical properties. This localized conductive layer modifies the electrostatic force distribution in specific areas, enabling different resonance frequencies in different regions of the same substrate while maintaining a unified manufacturing process.
Solution Approach 2:
The patent segments the membrane into regions with and without the first electrically-conductive layer, allowing independent frequency control. The second electrically-conductive layer is segmented into first and second electrodes that can be independently controlled, enabling simultaneous operation at multiple frequencies by applying different voltages to different segments.
2Manufacturing precision
If geometric and mechanical characteristics are fixed to determine resonance frequency, then manufacturing precision is improved, but adaptability to different frequencies is reduced
Solution Approach 1:
The patent changes the electrical parameters of the transducer by introducing electrically-conductive layers with specific resistance values and geometries. By modifying the electrical conductivity distribution on the membrane surface and electrode configurations, the resonance frequency can be adjusted without changing the physical geometry or mechanical properties of the membrane itself.
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 enables the formation of transducers capable of operating at different ultrasound frequencies using the same DC bias voltage, simplifying electronic control circuits and facilitating the creation of multifrequency ultrasound imaging devices.
Implementation Method 1
the flexible membrane starts vibrating under the effect of the variation of the electrostatic force exerted between the lower and upper electrodes, causing the emission of an ultrasound acoustic wave
Implementation Method 2
the flexible membrane starts vibrating under the effect of the mechanical pressure variation, causing the occurrence, between the lower and upper electrodes of the transducer, of an AC voltage superimposed to the DC bias voltage (due to the capacitance variation between the electrodes)
Implementation Method 3
The transmit frequency of a CMUT transducer generally corresponds to its resonance frequency, which depends on various parameters and in particular on the geometric and mechanical characteristics of the membrane and of the cavity
Data Source
AI summary
The present disclosure relates to a method of simultaneous manufacturing, from a same substrate (101), at least one first CMUT transducer (I) having a first resonance frequency and at least one second CMUT transducer (II) having a second resonance frequency different from the first frequency, the method comprising the steps of: a) for each transducer (I, II), forming a cavity (103) on the upper surface side of the substrate, and forming a flexible membrane (105) suspended above the cavity (103); b) forming a first layer (109) extending over a portion only of the upper surface of the membrane (105) of the first transducer (I) and which does not extend over the membrane (105) of the second transducer (II); and c) forming a second layer (111) extending over the entire upper surface of the membrane (105) of the first transducer and over the entire upper surface of the membrane of the second transducer.