Monolithic Plastic Conductivity Sensor for Single-Use Bioreactors
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Solution Overview
Problem
Conventional contact-type conductivity sensors are costly and prone to leaks due to material interfaces and sealing issues, limiting their effectiveness in measuring liquid conductivity.
Innovation Solution
A single-piece, monolithic plastic conductivity sensor is developed, where conductive electrodes and the sensor body are formed from the same thermoplastic compound, eliminating material interfaces and using conductive additives to ensure electrical conductivity, and are assembled by heating to fuse the components together, creating a unitary, leak-resistant structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional contact-type conductivity sensors use metal electrodes with plastic or ceramic/glass sensor bodies, then the sensor can measure liquid conductivity, but the sensor is costly and prone to leaks due to material interfaces and sealing issues
Solution Approach 1:
The patent merges the electrode material and sensor body into a single integrated structure. The conductive plastic material serves dual functions as both the sensor body and the electrode, eliminating the need for separate metal electrodes and plastic/ceramic sensor bodies. This integration removes the material interfaces and sealing structures that cause leaks, directly resolving the contradiction between leak resistance and device complexity.
Solution Approach 2:
The patent uses composite plastic materials containing conductive additives (such as carbon black, metal fibers, or conductive polymers) to create a material that is both structurally sound and electrically conductive. This composite material eliminates the need for separate conductive and insulating materials, removing the interfaces between them that lead to leakage issues.
2Ease of manufacture
If conventional sensors use separate metal electrodes and plastic sensor bodies, then conductivity measurement is possible, but manufacturing cost increases
Solution Approach 1:
By combining the electrode and sensor body into a single molded component, the patent eliminates multiple assembly steps. Instead of separately manufacturing metal electrodes and plastic sensor bodies and then assembling them with sealing structures, the entire sensor is molded as one piece from conductive plastic material, significantly reducing manufacturing complexity and cost.
Solution Approach 2:
The patent changes the electrical conductivity parameter of the plastic material by incorporating conductive additives. This allows the plastic to function as both the structural sensor body and the conductive electrode, simplifying the manufacturing process and reducing costs compared to using traditional metal electrodes.
3Reliability
If conventional sensors use metal electrodes with plastic sensor bodies, then the sensor structure is established, but sealing issues and leakage occur at material interfaces
Solution Approach 1:
The patent eliminates the interface between the electrode and sensor body by making them a single integrated component. Without this interface, there is no sealing problem, directly resolving the contradiction between sealing performance and the presence of harmful leakage paths.
Solution Approach 2:
The patent uses homogeneous conductive plastic material for both the sensor body and electrodes, eliminating the heterogeneity that creates interfaces. This uniform material structure removes the sealing issues that arise from different materials meeting at interfaces.
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
The solution significantly reduces manufacturing costs and minimizes leakage, enabling a low-cost, disposable conductivity sensor that is highly resistant to leaks, making it suitable for single-use applications while maintaining accurate conductivity measurements.
Implementation Method 1
conductive electrodes and the sensor body are formed from the same thermoplastic compound, eliminating material interfaces and using conductive additives to ensure electrical conductivity
Implementation Method 2
assembled by heating to fuse the components together, creating a unitary, leak-resistant structure
Data Source
Figure 1
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AI summary
A contacting-type conductivity sensor (10) includes an electrically-insulative plastic body (20) and a plurality of electrodes (12, 14, 16, 18). The plurality of conductive electrodes (12, 14, 16, 18) is disposed in the plastic body (20). Each electrode (12, 14, 16, 18) is constructed of plastic and fused with the electrically-insulative plastic body (20). A method of manufacturing the conductivity sensor is provided along with a single-use bioreactor (50) employing the sensor (10).