Hydrogel Microneedle Electrodes With Redox-Mediated Ketone Sensing
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Solution Overview
Problem
Current continuous glucose monitoring (CGM) devices are inadequate for continuous ketone body monitoring (CKM), as existing microneedle biosensors are invasive, biologically incompatible, and prone to signal retraction and breakage, while enzymatic detection of ketone bodies requires high potentials leading to fouling and non-specific detection.
Innovation Solution
A microneedle analyte sensing device with hydrogel-based electrodes, incorporating beta-hydroxybutyrate dehydrogenase, NAD+ cofactor, and redox mediators like dopamine, facilitates electrochemically mediated enzymatic reactions for continuous ketone monitoring, using a wearable transdermal patch with integrated electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solid microneedles are used for transdermal sensing, then penetration capability is improved, but biocompatibility deteriorates and immune responses are triggered
Solution Approach 1:
The patent changes the material parameter from solid metal to hydrogel polymer, transforming the physical state from rigid to soft and flexible. This parameter change maintains penetration capability through the stratum corneum while improving biocompatibility and eliminating immune responses associated with solid microneedles.
Solution Approach 2:
The patent uses composite hydrogel materials that integrate multiple functions: the hydrogel matrix provides biocompatibility and flexibility, while embedded conductive materials (such as carbon nanotubes, graphene, or conductive polymers) provide electrical conductivity for electrochemical sensing. This composite approach resolves the contradiction between mechanical properties and electrical functionality.
2Measurement precision
If solid microneedles are used for transdermal sensing, then initial signal detection is improved, but signal stability deteriorates due to progressive retraction
Solution Approach 1:
The patent employs flexible hydrogel microneedles that can deform and adapt to skin movement rather than maintaining a rigid structure. This flexibility prevents progressive retraction and maintains stable contact with the interstitial fluid, ensuring both initial signal detection and long-term signal stability.
Solution Approach 2:
The hydrogel material exhibits dynamic properties, allowing the microneedle to adapt its shape and position in response to skin deformation. This dynamic behavior maintains optimal sensing conditions over time, preventing signal degradation due to retraction while preserving measurement precision.
3Measurement precision
If high potential is applied for NADH oxidation, then detection sensitivity is improved, but surface fouling increases and non-specific detection occurs
Solution Approach 1:
The patent introduces redox mediators (such as quinones, phenazines, or metal complexes) that act as intermediaries between NADH and the electrode surface. These mediators facilitate electron transfer at lower potentials, maintaining detection sensitivity while preventing surface fouling and non-specific detection that occur at high potentials.
Solution Approach 2:
The patent replaces direct electrochemical oxidation (mechanical/electrical process at high potential) with an enzymatic catalysis approach using dehydrogenases. The enzyme catalyzes the oxidation of ketone bodies at physiological potentials, substituting the high-potential electrochemical process with a biological catalytic process that avoids surface fouling.
4Ease of operation
If conventional blood or urine strips are used for ketone monitoring, then measurement simplicity is improved, but monitoring continuity deteriorates to single time point measurements
Solution Approach 1:
The patent implements continuous monitoring by maintaining persistent contact between the hydrogel microneedle and interstitial fluid through flexible material properties. The hydrogel continuously absorbs and releases fluid, enabling sustained electrochemical measurements over extended periods while preserving ease of operation through simple patch application.
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 device enables continuous, non-invasive, and biocompatible monitoring of ketone bodies, overcoming signal retraction and fouling issues, allowing real-time tracking of ketone levels in diabetic patients.
Implementation Method 1
The resulting hydrogel microneedle electrode facilitates electron transfer and demonstrates effective performance for beta-hydroxybutyrate detection
Implementation Method 2
incorporating beta-hydroxybutyrate dehydrogenase, NAD+ cofactor, and redox mediators like dopamine, facilitates electrochemically mediated enzymatic reactions
Implementation Method 3
hydrogel-based electrodes
Data Source
AI summary
The present disclosure relates to a microneedle analyte sensing device for continuous monitoring of an analyte in a user's biological fluid, specifically designed for detecting ketone levels in diabetic ketoacidosis (DKA) management. The disclosed microneedle analyte sensing device utilizes dopamine (DA) molecules covalently linked to the microneedle patch's polymer structure or toluidine blue O (TBO), serving as a redox mediator for measuring the oxidation byproduct of 3-beta-hydroxybutyrate (β-HB). The sensing mechanism relies on catechol-quinone chemistry, where a pre-oxidation approach correlates sensor response to β-HB concentrations. The device comprises a plurality of microneedles on a substrate that, when applied to the skin, penetrate the stratum corneum to contact biological fluid. At least one microneedle functions as a working electrode to detect an electrochemical signal from the enzymatic reaction with the analyte, while additional microneedles serve as counter and reference electrodes to facilitate accurate electrochemical measurements.