Enzymatic Glucose Sensor Structure for Low Decay and Short Lag
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Solution Overview
Problem
Conventional glucose sensors face challenges due to limited surface area and volume, leading to sensor agent depletion, poor signal-to-noise ratios, and short operational lifespans, exacerbated by foreign body responses and diffusion delays, necessitating improved systems for continuous glucose monitoring.
Innovation Solution
The development of an enzymatic electrochemical glucose sensor with a lead assembly and electronics system that is partially positioned within a fluid-filled lumen, featuring a flexible lead with a specific electrode surface area and membrane configuration, maintaining a high signal-to-noise ratio and reducing amperage decay and time delay over a year.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the surface area and volume of the sensing element are reduced to prevent insertion pain and discomfort, then user comfort is improved, but the amount of glucose sensing agent that can be incorporated is limited, leading to sensor agent depletion and short operational lifespan
Solution Approach 1:
The sensing element is segmented into multiple discrete sensing sites or micro-electrodes distributed across the surface. This segmentation allows the total sensing agent capacity to be distributed across multiple small units, each contributing to the overall signal while maintaining a small individual footprint that minimizes tissue disruption and foreign body response.
Solution Approach 2:
The patent employs a nested structure where the sensing element is integrated within a biocompatible housing or coating matrix. This nesting allows the sensing agent to be embedded within a protective matrix that increases the effective volume for agent incorporation while maintaining a small external dimensions for comfort. The matrix may also include porous structures that provide additional surface area for agent loading.
2Measurement precision
If the surface area of the sensing element is increased to increase the sensor current level and improve signal-to-noise ratio, then measurement precision is improved, but the sensor size and volume increase, causing pain and discomfort to the user
Solution Approach 1:
The sensing element employs local quality by concentrating the sensing agent in specific high-density regions or zones rather than uniform distribution. This creates localized areas of high signal generation capability that improve the overall signal-to-noise ratio without requiring a proportional increase in total surface area. The non-uniform distribution optimizes signal output while minimizing the physical footprint.
Solution Approach 2:
The patent transitions from a two-dimensional surface-based sensing approach to a three-dimensional volumetric sensing structure. By incorporating the sensing agent throughout a volumetric matrix or using vertically stacked electrode structures, the effective sensing capacity is increased in the third dimension without increasing the lateral surface area that contacts tissue, thereby improving signal output while maintaining comfort.
3Duration of action of moving object
If the membrane thickness is increased to accommodate more glucose oxidase, then the operational lifespan is extended, but diffusion delays occur resulting in clinically unacceptable lag time
Solution Approach 1:
The membrane is constructed as a porous matrix with controlled pore size and distribution. This porous structure provides a three-dimensional network that can accommodate a high concentration of glucose oxidase throughout the membrane volume while maintaining short diffusion pathways through the pore channels. The porous architecture increases the effective surface area and enzyme loading capacity without proportionally increasing the linear thickness, thereby extending operational lifespan while minimizing diffusion lag time.
Solution Approach 2:
The patent employs a thin-film membrane structure with vertically oriented enzyme layers or stacked catalytic planes. This dimensional arrangement allows multiple layers of glucose oxidase to be incorporated within a minimal thickness by utilizing the vertical dimension. Glucose can diffuse through the thin membrane rapidly while encountering multiple enzyme layers in sequence, achieving both fast response and extended enzyme capacity.
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 sensor achieves a current amperage decay rate of no greater than 40% over a year and a time delay of no more than 2 minutes, providing reliable glucose level monitoring without recharging for extended periods, up to two years.
Implementation Method 1
sensors using glucose oxidase as the sensing agent
Implementation Method 2
The glucose oxidation reaction is a well-established metric that is used in glucose monitoring
Implementation Method 3
diffusion of glucose and oxygen into the sensing element
Implementation Method 4
an enzymatic electrochemical glucose sensor... configured to generate data indicative of a glucose level
Data Source
AI summary
A device for continuously monitoring glucose levels in a patient includes a lead assembly in electrical communication with an electronics assembly. The electronics assembly is configured to be positioned in the subcutaneous tissue and the lead assembly is configured to be positioned in a vessel of the patient, such as in a vein or in an epidural space. The lead assembly has a lumen, and includes at least one electrode in electrical communication with the electronics assembly.