Microfluidic Pillar Electrodes for Impedance Measurement of Spheroids
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Solution Overview
Problem
Existing microfluidic devices for electrical impedance measurement of biological objects, such as spheroids, face issues with electrodes that are either in contact with the object or too far away, non-transparent materials, unsuitable device configurations for visualization, and lack of perfusion capability, making it difficult to perform reliable impedance measurements close to the object and monitor its surrounding environment.
Innovation Solution
A microfluidic component with a trapping device comprising central and lateral pillars acting as electrodes, connected to a potentiostat, allowing for electrical impedance measurements close to the biological object, enabling perfusion, and monitoring the surrounding environment, using a support with a main microfluidic channel and lateral channels for fluid circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coplanar electrodes are used in existing microfluidic devices, then the device structure is simple, but the electrodes are either in contact with the biological object or too far away, preventing optimal field penetration and reliable impedance measurements
Solution Approach 1:
The patent transitions from coplanar electrodes to three-dimensional pillar structures extending into the fluid channel. The pillars are positioned at specific heights (e.g., 50-150 μm) to optimize field penetration through the biological object without requiring electrode contact, resolving the measurement accuracy issue while maintaining structural feasibility
Solution Approach 2:
The patent introduces a trapping device comprising pillars as an intermediary structure between the electrodes and the biological object. These pillars position the electrodes at optimal distances and create controlled field lines that penetrate the object effectively, mediating the interaction between electrodes and biological sample
2Ease of manufacture
If non-transparent materials are used for integrating electrodes, then the electrode integration is simple, but the biological object cannot be visualized and monitored using transmission microscopy
Solution Approach 1:
The patent applies different material properties to different regions: the support structure and trapping device use transparent materials (glass, PDMS, cyclic olefin copolymer) in the measurement zone to enable microscopy, while electrode connections use conductive materials (gold, platinum, ITO) only where electrically necessary. This local differentiation resolves both manufacturing simplicity and visualization requirements
Solution Approach 2:
The device combines transparent structural materials with conductive electrode materials in a composite construction. The support may be glass or transparent polymer with integrated transparent conducting oxide layers or metal traces, creating a multi-material system that simultaneously provides structural integrity, electrical functionality, and optical transparency
3Ease of manufacture
If the device configuration is not suitable for perfusion, then the trapping structure is simple, but the biological object cannot be perfused or its surrounding environment monitored
Solution Approach 1:
The patent designs the microfluidic channel system to serve multiple functions: the main channel transports and traps biological objects, lateral channels enable perfusion of the surrounding environment, and the same trapping pillars serve both as structural elements and as electrode support. This multi-functionality resolves the contradiction between structural simplicity and perfusion capability
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 reliable electrical impedance measurements near the biological object, permits perfusion, and allows monitoring of the surrounding fluidic environment, suitable for visualization and perfusion, using mastered manufacturing technologies.
Implementation Method 1
measuring electrical impedance through a biological object... Studies show that there may be a correlation between the viability of cells present in the spheroid and electrical impedance measurements across the spheroid
Implementation Method 2
Apply a first electrical potential to the electrode of the first central pillar, a second electrical potential to the electrode of the second central pillar... to come to monitor that area of interest
Data Source
Figure 1~2
Figure 3A~3B
Figure 3C~3D
AI summary
The invention relates to a microfluidic component used for electrical impedance measurement through a biological object (O), said microfluidic component comprising: - A support in which is made a main microfluidic channel (C_1) defining a path for the circulation of a fluid containing the biological object (O), - A trapping device positioned in the main microfluidic channel (C_1) on the circulation path of said biological object, - At least one first electrode and a second electrode intended to be each brought to a distinct electrical potential, in order to perform said impedance measurement, - Said trapping device being composed of at least one first central pillar (P_1) and a second central pillar (P_2) positioned inside the microfluidic channel, - The first central pillar being configured to form the first electrode and the second central pillar being configured to form the second electrode.