Multiplexed Electrical Impedance Tomography for Real-Time Fluid Visualization
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Solution Overview
Problem
Current tomographic techniques for fluid processing in industrial settings, such as Electrical Resistance Tomography (ERT), Electrical Capacitance Tomography (ECT), and Electrical Impedance Tomography (EIT), are limited by their serial sensing approach, which restricts frame rates and measurement intervals, making them time-consuming and inefficient for real-time visualization of fluid properties.
Innovation Solution
The implementation of a multiplexed sensing approach using Code Division Multiplexing (CDM) with Pseudo-Random Noise Codes, such as M-sequences or Gold-codes, allows for simultaneous injection of current signals into multiple electrodes, enabling synchronous detection and decoding of signals to separate and decode the measurements, thereby overcoming the limitations of serial sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a serial sensing approach is used for tomographic measurements, then the measurement process is simple to implement, but the frame rate is limited and the process is time-consuming
Solution Approach 1:
Multiple electrode measurements are merged into simultaneous operations through code division multiplexing. Different electrode pairs are assigned unique pseudo-random codes, allowing their measurements to be combined in the time domain and separated through correlation processing, achieving parallel measurement capability from a shared hardware platform
Solution Approach 2:
Pseudo-random noise codes with periodic properties are used to modulate the excitation signals applied to different electrode pairs. The periodic correlation properties of these codes enable synchronous detection and separation of overlapping measurements, allowing high-speed sequential access to multiple electrode combinations
2Measurement precision
If measurement intervals are extended to improve signal-to-noise ratio, then measurement precision improves, but the frame rate decreases
Solution Approach 1:
Instead of performing discrete sequential measurements that require idle intervals, the system maintains continuous useful action by overlapping multiple measurements in time. Pseudo-random coded excitation signals allow simultaneous application to multiple electrode pairs with continuous data acquisition, eliminating dead time between measurements
Solution Approach 2:
Pseudo-random codes are applied as preliminary modulation to the excitation signals before measurement. This pre-encoding allows the system to prepare multiple measurement channels in advance, with each channel's data separable through correlation with its unique code, enabling parallel processing of what would otherwise require sequential execution
Data Source
AI summary
Apparatus is provided featuring a signal processor or processing module configured at least to: receive signaling containing information about coded and multiplexed voltages measured across pairs of electrodes in an array of electrodes configured in relation to a fluid processing structure, including a pipe, tank, vessel, vat or container, having a process fluid therein; and determine using a tomographic signal processing algorithm a tomographic indication of the process fluid, based at least partly on the signaling received. The signal processor module may be configured to provide corresponding signaling containing information about the tomographic indication of the process fluid. The tomographic indication includes a 2D or 3D image or visualization of the process fluid, including an analysis of mixing in multiphase flows, liquid interfaces or liquid-froth layers detected in the process fluid.