Non-contact Impedance Analyzer for Microbial Growth Detection
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Solution Overview
Problem
Current methods for real-time detection of microbial growth in commercial labware with insulated walls are labor-intensive, costly, and lack the ability to perform high-throughput, non-contact measurements, especially when using off-the-shelf equipment.
Innovation Solution
A docking system with non-contact electrodes that can reproducibly attach and detach from the insulated walls of containers, allowing for physical contact at preselected locations, enabling real-time electrochemical detection of microbial growth without direct contact, using a docking arrangement with movable elements and electrical connectors connected to an analyser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrodes are placed in direct contact with growing bacteria, then real-time electrochemical detection is enabled, but custom system manufacturing is required and complexity increases
Solution Approach 1:
The patent introduces an insulating barrier (e.g., glass slide, plastic cover slip) as an intermediary between the electrodes and the bacterial culture. This mediator allows the electric field to penetrate through to the bacteria while preventing direct contact, thereby eliminating the need for custom-manufactured electrodes with exposed contacts and enabling the use of standard insulating labware.
Solution Approach 2:
The patent replaces the mechanical contact-based electrode configuration with a capacitive coupling system where electrodes are positioned close to but not touching the culture medium. This substitution eliminates the need for complex mechanical alignment and custom electrode fabrication while maintaining detection capability through electric field interaction.
2Ease of operation
If non-contact electrodes are used with insulating labware, then ease of operation improves, but measurement precision deteriorates due to spacing variations
Solution Approach 1:
The patent applies conductive adhesive tape to the outer surface of the insulating labware before inserting it into the measurement chamber. This preliminary action creates a consistent, conductive interface that ensures reliable electrical contact between the electrodes and the labware surface, eliminating spacing variations and enabling quantitative measurements while maintaining ease of operation with standard labware.
Solution Approach 2:
The patent modifies the electrical properties of the labware surface by applying conductive adhesive, thereby changing the interface characteristics from insulating to conductive. This parameter change enables consistent electrical coupling between the electrodes and labware while preserving the mechanical and chemical properties of the original insulating labware.
3Measurement precision
If biochemical phenotype methods are used for sampling and analysis, then detection capability is achieved, but time consumption and labor intensity increase
Solution Approach 1:
The patent implements continuous real-time monitoring of microbial growth through electrochemical impedance measurements. Instead of periodic sampling and discrete analysis steps, the system continuously tracks changes in electrical properties of the culture medium, providing uninterrupted data on microbial growth without removing samples from the culture environment.
Solution Approach 2:
The patent replaces mechanical sampling operations (pipetting, transferring, processing physical samples) with electrical field-based detection. By measuring changes in electrical impedance caused by microbial metabolism, the system eliminates time-consuming manual sampling and laboratory processing steps while providing equivalent or superior detection information.
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 rapid, high-throughput, and reproducible detection of microbial growth in various labware types, minimizing spacing and ensuring accurate, quantitative measurements by maintaining consistent pressure and contact between electrodes and container surfaces.
Implementation Method 1
Applying electrical signals to living cells causes reactions with the components of the cells and frequency dependent polarization, which can be related to the polar nature of lipid membranes, proton gradients on the outer surface of viable cells, and membrane-associated electron transfer reactions linked to metabolic activity. Simplified, this behaviour of the cells can be described in terms of capacitance, electrical permittivity and conductivity.
Implementation Method 2
Applying electrical signals to living cells causes reactions with the components of the cells and frequency dependent polarization, which can be related to the polar nature of lipid membranes, proton gradients on the outer surface of viable cells, and membrane-associated electron transfer reactions linked to metabolic activity. Simplified, this behaviour of the cells can be described in terms of capacitance, electrical permittivity and conductivity.
Implementation Method 3
Applying electrical signals to living cells causes reactions with the components of the cells and frequency dependent polarization, which can be related to the polar nature of lipid membranes, proton gradients on the outer surface of viable cells, and membrane-associated electron transfer reactions linked to metabolic activity. Simplified, this behaviour of the cells can be described in terms of capacitance, electrical permittivity and conductivity.
Implementation Method 4
The variation in capacitance and resistance can readily be measured by an analyser using electrochemical-impedance-spectroscopy (EIS). EIS is a fast, sensitive, and label-free technique that can characterize (bio)physical processes at the substrate-biomaterial interface.
Data Source
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Figure 4A~5
AI summary
A device and method for real-time quantitative detection of growth of microorganisms in one or more containers through one or more electrically insulated walls of each container is provided with at least one set of electrodes physically separated from each other and being adapted to establish one or more contact interfaces with insulated walls of each container. The device comprises a docking station, which is adapted to attach and detach each container, ensuring that the electrodes are positioned at the contact interfaces with predefined positions. The device further comprises at least one set of one or more electrical connectors adapted for electrical connections to the sets of electrodes. Connecting the device to an impedance analyser enables growth of microorganisms to be detected in real time with no physical contact between the samples of microorganisms and the electrodes.