Cell Impedance Signal Processing for Morphology Classification
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Solution Overview
Problem
Existing hematological analysis methods, particularly those based on the Coulter Principle, lack the ability to determine the strain index or a simplified version of it, and are unable to efficiently classify cell populations based on morphological characteristics, requiring complex and expensive optical or video microscopy systems.
Innovation Solution
A method involving impedance pulse analysis using defined coefficients to calculate high and low impedance values, determining peak position and rotation values, and employing neural networks to classify cells based on their impedance pulses, allowing for the characterization of cell morphological characteristics without hydrodynamic focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical or video microscopy systems are used to determine strain index and classify cell populations, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces optical/mechanical microscopy systems with an electrical impedance-based measurement system. Instead of using optical lenses, cameras, and mechanical stage systems to capture and analyze cell images, the invention uses electrical signals to measure cell properties including strain index. The impedance measurement system detects changes in electrical properties of cells as they pass through an orifice, eliminating the need for complex optical hardware while achieving comparable or superior measurement precision.
Solution Approach 2:
The patent measures multiple electrical parameters (impedance, conductivity, capacitance) simultaneously to characterize cells. By changing the measurement parameter from optical properties (absorption, reflection) to electrical properties (impedance, conductivity), the system achieves strain index determination and cell classification without requiring complex optical systems. The multi-parameter electrical measurement approach provides rich cell characterization data using simpler, more compact hardware.
2Loss of information
If multiple electrical parameters are measured simultaneously, then information on cell morphology and deformability is improved, but signal processing complexity increases
Solution Approach 1:
The patent segments the electrical signal into distinct components corresponding to different cell properties. The impedance signal is divided into separate measurements for cell size, morphology, and deformability characteristics. By segmenting the measurement process and analyzing specific portions of the signal separately, the system extracts multiple cell parameters without requiring overly complex simultaneous processing of all signals at once.
Solution Approach 2:
The patent performs preliminary signal conditioning and feature extraction before full analysis. Raw electrical signals are pre-processed to remove noise, identify cell passage events, and extract key features such as peak impedance values and signal duration. This preliminary action simplifies subsequent analysis by providing cleaned, structured data that requires less complex processing to derive morphological and deformability information.
3Measurement precision
If hydrodynamic focusing is implemented to center cell flow in the orifice, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the hydrodynamic focusing subsystem from the measurement system. Instead of using auxiliary fluids and complex flow control mechanisms to center cells in the orifice, the invention uses a simpler direct flow approach combined with electrical signal analysis to detect and characterize cell passages. The system takes out the hydrodynamic focusing complexity while maintaining measurement precision through alternative electrical measurement strategies.
Solution Approach 2:
The patent employs a simpler, more disposable-friendly orifice design that does not require the precision manufacturing and alignment tolerances needed for hydrodynamic focusing systems. The orifice is designed to work effectively with straightforward cell suspension flow, making the system more robust and easier to manufacture. This approach accepts some variation in cell positioning but compensates through electrical signal analysis that can detect cell properties regardless of exact position.
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
Enables precise classification of cell populations by providing statistical distributions and neural network-based classification, achieving high accuracy in distinguishing normal from abnormal cells and monitoring sample evolution, all while avoiding the complexity and cost of optical systems.
Implementation Method 1
passing the cells suspended in a conductive liquid through a polarized micro-orifice and detecting the variations in electrical resistance (or impedance variations) induced by the passage of particles in the orifice
Data Source
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AI summary
A medical analysis device with cellular impedance signal processing comprises a memory (4) arranged to receive pulse data sets, each pulse data set comprising impedance value data that are associated each time with a time marker, these data together representing a curve of cellular impedance values that are measured as a cell passes through a polarised opening. This device further comprises a classifier (6) comprising a convolutional neural network receiving the pulse data sets as input and is provided with at least one convolutional layer, which convolutional layer has a depth greater than or equal to 3, and at least two fully connected layers, in addition to an output layer rendering a cell classification from which a pulse data set is derived.