Method for producing an electrical impedance tomographic image of an acoustic field and a system for performing said method
Inventors
Palmer, Timothy John • Bean, Edward Leigh • Tegerdine, David Roger
Assignees
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Publication Number
US-10488356-B2
Publication Date
2019-11-26
Expiration Date
Abstract
There is provided A method for producing an electrical impedance tomographic image of an acoustic field within a fluid, comprising the steps of: a) positioning a plurality of electrodes within a fluid; b) applying an electrical signal to each electrode within a first subset of electrodes, wherein the electrical signal applied to each electrode has a different carrier frequency and/or phase; c) measuring the electrical potential at each electrode within a second subset of electrodes; and d) processing the measured data to provide an acoustic map of the acoustic field at the required acoustic frequencies. There is also provided a system for producing an electrical impedance tomographic image of an acoustic field within a fluid using the method of any preceding claim, comprising a plurality of electrodes, a signal generator adapted to perform step (b), a device adapted to perform step (c), and a processor adapted to perform step (d).
Core Innovation
The invention produces an electrical impedance tomographic image of an acoustic field within a fluid by positioning a plurality of electrodes within the fluid. Electrical signals are applied to each electrode within a first subset of electrodes, where each electrical signal has a different carrier frequency and/or phase. Electrical potentials are measured at each electrode within a second subset of electrodes, and the measured data are processed to provide an acoustic map of the acoustic field at required acoustic frequencies.
A key aspect is how the excitation and measurement are performed using two electrode subsets, enabling impedance data to be used for tomographic processing. Impedance is measured between electrode pairs and processed to generate the acoustic map at the required acoustic frequencies. The invention also supports optional one-dimensional measurement based on a single electrode pair, where the signal strength is a function of the measured electrical impedance.
The invention further addresses non-acoustic electrical-environment effects by measuring impedance across a frequency range and compensating for global longer-term trends. These trends can include temperature, pressure, chemical composition, electrode composition, and surface effects. The carrier frequency and/or phase are selected so that the electrical properties of the measurement fluid remain substantially unchanged or that any variation with frequency and/or phase is known. The approach is implemented with system components including a signal generator, an electrical signal detector, and a tomographic processor, with electrode layouts that can be configurable, including linear/planar/conformal arrangements.
Claims Coverage
Independent claims clm-00001 and clm-00016 define the method of producing an electrical impedance tomographic image of an acoustic field in a fluid, using two electrode subsets and impedance-based acoustic mapping. Across these independent claims, the inventive features include subset-based carrier frequency/phase excitation and electrode-potential measurement, followed by processing to produce an acoustic map at required acoustic frequencies; clm-00016 additionally limits the subsets to single electrodes to provide one-dimensional measurement where signal strength is a function of impedance.
Subset excitation with different carrier frequencies and/or phases
Positioning a plurality of electrodes within a fluid and applying an electrical signal to each electrode within a first subset of electrodes, wherein the electrical signal applied to each electrode has a different carrier frequency and/or phase.
Subset electrical potential measurement and acoustic map processing
Measuring the electrical potential at each electrode within a second subset of electrodes, and processing the measured data to provide an acoustic map of the acoustic field at the required acoustic frequencies.
One-dimensional electrode-pair impedance with signal strength as a function of impedance
Configuring the first and second subsets each to comprise only a single electrode, wherein the electrical impedance is measured across the resulting electrode pair to provide a one-dimensional measurement of acoustic signal strength across the electrode pair, and wherein the signal strength is a function of the measured electrical impedance.
Overall, the claim coverage centers on impedance-based acoustic mapping from electrode subset excitation using carrier frequency and/or phase diversity, coupled with processing of measured electrical potentials into an acoustic map at required acoustic frequencies. A further core coverage point is restricting both subsets to single electrodes to obtain one-dimensional acoustic signal strength from electrode-pair impedance, with signal strength defined as a function of the measured impedance.
Stated Advantages
Compensation for non-acoustic electrical-environment trends by measuring impedance across a frequency range.
Ability to provide both acoustic map imaging and optional one-dimensional measurement of acoustic signal strength across an electrode pair.
Documented Applications
Imaging a 3D acoustic field in a fluid using electrical impedance tomography (EIT) with electrode arrays.
SONAR-related acoustic field imaging.
Conductive fluid use, including seawater, with electrodes positioned to create directionality via configurable electrode layouts.
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