Disposable pH Sensor with Locking Plunger for Bioreactor Sterilization
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Solution Overview
Problem
The existing pH sensors used in fermentation and cell culture processes face challenges due to high temperatures and rapid thermal shocks during sterilization, leading to reduced sensor lifespan and inaccurate temperature compensation, especially when transitioning from storage to operating conditions within single-use bioreactors.
Innovation Solution
Incorporating a temperature-sensitive element within the pH sensor assembly to ensure accurate temperature measurement and a locking mechanism to prevent the glass electrode from being pushed back during operation, along with improved filling methods for sealed cavities to prevent air bubbles and enhance manufacturability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a pH sensor is used in single-use bioreactors, then the capital cost is reduced and facility flexibility is improved, but the sensor is exposed to high temperatures and thermal shocks during sterilization which reduces sensor lifespan
Solution Approach 1:
The patent describes a disposable pH sensor system where the sensor is designed for single-use in bioreactors. The sensor is discarded after one use, eliminating the need for expensive sterilization processes and protecting the sensor from thermal damage. This approach trades the reusability of expensive sensors for the cost-effectiveness of disposable units, resolving the contradiction between capital cost reduction and sensor lifespan.
2Reliability
If the pH sensor is sterilized using steam cleaning, then cross batch contamination is prevented, but the high temperatures and rapid thermal shock significantly affect the sensor's life
Solution Approach 1:
The patent extracts the sterilization requirement from the sensor by making the sensor disposable. Instead of subjecting the sensor to sterilization processes, the entire sensor unit is discarded after single use, eliminating thermal shock damage while maintaining contamination prevention through single-use design.
Solution Approach 2:
The disposable sensor design eliminates the need for sterilization of the sensor itself. Each sensor is used once and then discarded, preventing cross-contamination without exposing the sensor to damaging sterilization conditions, thus resolving the contradiction between reliability and lifespan.
3Ease of operation
If the glass electrode is pushed into the bioreactor bag through a sliding mechanism, then the sensor can be activated and used, but the electrode may be pushed back during operation causing de-activation
Solution Approach 1:
The patent implements a locking mechanism that prevents the plunger from moving backward after insertion. The lock member engages with the plunger to maintain the electrode in its inserted position, providing preliminary protection against de-activation forces that may occur during operation.
Solution Approach 2:
The locking mechanism is engaged after insertion to secure the electrode in its operational position. This preliminary action of locking prevents any subsequent backward movement, ensuring the sensor remains activated throughout the measurement process.
4Productivity
If sealed cavities are filled during manufacturing, then the sensor is ready for use, but air bubbles may be trapped reducing measurement accuracy
Solution Approach 1:
The patent describes filling sealed cavities with reference electrolyte solution during the manufacturing process before final assembly. This preliminary filling action ensures that no air bubbles are trapped in the cavities, maintaining measurement accuracy while enabling efficient manufacturing.
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 provides precise temperature compensation and prevents sensor de-activation, enhancing the accuracy and reliability of pH measurements while improving manufacturing efficiency and reducing sensor failure rates.
Implementation Method 1
a temperature sensitive element is disposed within the pH sensor and configured to sense temperature proximate the pH sensing element
Data Source
AI summary
A pH sensor for a single-use container includes a plunger sleeve configured to couple to a flange of the single-use container. A plunger is axially movable within the plunger sleeve between a storage position and an operating position. A pH sensing element coupled to the plunger wherein the pH element is disposed within a storage chamber in the storage position and is configured to be exposed to an interior of the single-use container in the operating position. In one example, a temperature sensitive element is disposed within the pH sensor and configured to sense temperature proximate the pH sensing element. In another example, a lock member is coupled to the plunger, where the lock member has a locked position and an unlocked position, the lock member being configured to inhibit movement of the plunger when in the locked position. In yet another example, the plunger includes at least one filling channel that allows access to a reference fill chamber when the plunger is in a filling position.