Enzyme Immobilization Network for Sterilization-Resistant Continuous Sensors
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Solution Overview
Problem
Conventional continuous glucose monitoring (CGM) sensors have a limited useful life due to enzyme layer instability, which is exacerbated by sterilization processes like EtO gas, leading to reduced sensitivity and the need for frequent replacements and calibrations, causing inconvenience and increased costs.
Innovation Solution
A working wire for a continuous biological sensor is developed with an enzyme immobilization network stabilized by a combination of polymeric and non-polymeric crosslinking agents, such as PEG dialdehyde and glutaraldehyde, which enhances enzyme stability and resistance to sterilization, allowing for improved sensitivity and extended sensor life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional enzyme layers are used in CGM sensors, then the sensors can be manufactured and sterilized, but the enzyme layer becomes unstable and loses sensitivity over time, requiring frequent replacements
Solution Approach 1:
The patent applies preliminary action by crosslinking the enzyme layer with glutaraldehyde before sterilization to pre-stabilize the enzyme structure. This pre-treatment prevents enzyme denaturation and sensitivity loss that would otherwise occur during subsequent sterilization processes, thereby extending the sensor's useful life while maintaining reliability
Solution Approach 2:
The patent uses composite materials by combining the enzyme layer with a crosslinking agent (glutaraldehyde) to create a stabilized enzyme-copolymer complex. This composite structure provides both the catalytic function of the enzyme and the structural stability of the crosslinked network, resolving the contradiction between reliability and duration
2Object-affected harmful factors
If sterilization processes like EtO gas are applied to CGM sensors, then the sensors become sterile for implantation, but the sterilization damages the enzyme layer and reduces sensitivity
Solution Approach 1:
The patent applies beforehand cushioning by introducing a protective crosslinked network into the enzyme layer prior to sterilization. This crosslinked structure acts as a cushion that protects the enzyme from the damaging effects of EtO gas sterilization, maintaining measurement precision while achieving the required sterilization effectiveness
Solution Approach 2:
The patent converts the harmful effect of sterilization into a benefit by using the crosslinking process to create a more stable enzyme structure that is inherently more resistant to sterilization damage. The crosslinked enzyme-copolymer complex transforms the vulnerability of the enzyme layer into enhanced stability and sensitivity retention
3Reliability
If the enzyme layer is made more stable through crosslinking, then sensitivity is improved and sensor life is extended, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges the enzyme immobilization process with the crosslinking process into a single integrated step. The enzyme layer is applied to the sensor substrate and simultaneously crosslinked with glutaraldehyde, combining two manufacturing operations into one. This reduces overall process complexity while achieving the desired enzyme stability and sensitivity
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 enzyme immobilization network significantly increases sensor stability and sensitivity, reducing the need for replacements and calibrations, while enabling effective gas sterilization without sensitivity loss, thus providing a more cost-effective and reliable CGM system.
Implementation Method 1
The enzyme immobilization network is formed using a polymeric crosslinking agent and a non-polymeric crosslinking agent crosslinking the enzyme and the immobilization matrix. The polymeric crosslinking agent and the non-polymeric crosslinking agent are a combination of polyethylene glycol (PEG) dialdehyde and glutaraldehyde.
Implementation Method 2
An enzyme layer is on the conductive surface and includes an enzyme, an immobilization matrix, and an enzyme immobilization network
Implementation Method 3
Electrochemical glucose sensors operate by using electrodes which typically detect an amperometric signal caused by oxidation of enzymes during conversion of glucose to gluconolactone.
Data Source
AI summary
A working wire of a continuous biological sensor is disclosed. The working wire includes a substrate for the sensor having a conductive surface. An enzyme layer is on the conductive surface and includes an enzyme, an immobilization matrix, and an enzyme immobilization network. The enzyme immobilization network is formed using a polymeric crosslinking agent and a non-polymeric crosslinking agent crosslinking the enzyme and the immobilization matrix. The polymeric crosslinking agent and the non-polymeric crosslinking agent are a combination of polyethylene glycol (PEG) dialdehyde and glutaraldehyde. A protective layer is over the enzyme layer.