Measurement of glucose near an insulin delivery catheter by minimizing the adverse effects of insulin preservatives: alternative ligands and redox mediator metals
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Solution Overview
Problem
Current insulin formulations interfere with hydrogen peroxide-measuring sensors, leading to device burden and inefficiencies in managing Type 1 Diabetes, as multiple devices are required for insulin delivery and glucose monitoring, increasing pain, infection risk, and frustration due to device multiplicity.
Innovation Solution
Integration of a glucose sensor with an insulin cannula using alternative redox mediators and coordinating ligands, such as metals like osmium, ruthenium, iridium, and cobalt, bound to ligands like pyridine and imidazole, located within a predetermined distance from the cannula tip, allowing for continuous glucose monitoring and insulin delivery in a single device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single integrated device is used for both insulin delivery and glucose monitoring, then device burden is reduced and user compliance improves, but insulin preservatives (phenol and m-cresol) interfere with the glucose sensor measurements
Solution Approach 1:
The patent introduces a redox mediator (osmium complex with pyridine or imidazole ligands) as an intermediary between glucose and the electrode. This mediator enables electron transfer at lower potentials where phenolic preservatives do not interfere, allowing accurate glucose measurement despite the presence of electroactive preservatives in the insulin formulation
Solution Approach 2:
The patent changes the electrochemical measurement parameters by using a redox-mediated system that operates at lower potentials compared to direct oxidation. This parameter change shifts the measurement window away from the interference region of phenolic preservatives, enabling simultaneous insulin delivery and glucose monitoring without cross-interference
2Measurement precision
If conventional hydrogen peroxide-measuring sensors are used, then glucose monitoring is achieved, but insulin preservatives cause electroactive interference and sensor failure
Solution Approach 1:
The redox mediator acts as an intermediary that transfers electrons from glucose oxidase to the electrode at lower potentials, avoiding direct oxidation of hydrogen peroxide and eliminating interference from electroactive phenolic preservatives that would otherwise poison the sensor
Solution Approach 2:
The patent converts the challenge of measuring glucose in the presence of electroactive preservatives into an opportunity by using redox mediation, which enables measurement at potentials where preservatives are electrochemically inactive, thus turning a harmful interference scenario into a beneficial selective measurement approach
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 continuous glucose monitoring at the site of insulin delivery, reducing device burden, minimizing interference from insulin preservatives, and maintaining sensor sensitivity over time, thus improving glycemic control and user experience.
Implementation Method 1
a redox mediator comprising a metal compound covalently bound to a ligand
Implementation Method 2
an enzyme comprising glucose oxidase or glucose dehydrogenase
Data Source
AI summary
A device for delivery of an insulin or insulin analog formulation and measurement of subcutaneous glucose concentration may comprise a hollow tube, and an amperometric glucose sensor located proximal to a distal end of the hollow tube. The amperometric glucose sensor may comprise a redox mediator and an enzyme comprising glucose oxidase or glucose dehydrogenase. An applied bias potential may allow an electrode layer of the amperometric glucose sensor to undergo substantially no electropolymerization of an excipient of the insulin or insulin analog formulation during continuous operation of amperometric glucose sensor. A sensitivity of the amperometric glucose sensor to the subcutaneous glucose concentration may be maintained in presence of the insulin or insulin analog formulation.