Enzyme Sensor Using dV/dt Redox Signals for Low-Concentration Detection
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Solution Overview
Problem
Existing enzyme sensors face challenges in accurately measuring low concentrations of organic substances in biological fluids due to irreversibility of enzyme reactions, potential stabilization issues, and reduced measurement accuracy, making it difficult to monitor concentration changes over time.
Innovation Solution
An enzyme sensor with a working electrode and standard electrode, immobilized with a redox substance, outputs a time differential value (dV/dt) of potential difference, which shifts based on enzyme-substrate reactions, allowing for high-accuracy measurement of substrate concentration changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an enzyme sensor is used to detect low concentrations of organic substances in biological fluids, then sensitivity is improved, but measurement accuracy deteriorates due to irreversibility of enzyme reactions and potential stabilization issues
Solution Approach 1:
The patent introduces a redox substance as an intermediary between the enzyme and the electrode. The redox substance mediates electron transfer from the enzyme reaction products to the electrode, enabling reversible measurement. The redox couple (oxidized/reduced forms) acts as a mediator that shuttles electrons back and forth, making the irreversible enzyme reaction measurable as a reversible electrochemical signal.
Solution Approach 2:
The patent measures the time differential value (dV/dt) of potential difference rather than steady-state potential. This parameter change from static potential measurement to dynamic rate measurement allows accurate detection of low substrate concentrations while avoiding the problem of potential stabilization, as the measurement captures the instantaneous rate of change before equilibrium is reached.
2Measurement precision
If steady potential measurement is used to estimate substrate concentration, then measurement simplicity is improved, but measurement precision deteriorates due to potential stabilization issues
Solution Approach 1:
The patent changes the measurement parameter from steady potential (V) to time differential of potential (dV/dt). This allows measurement of substrate concentration based on the initial rate of change before potential stabilization occurs, providing both high precision and a relatively simple measurement approach that only requires potential monitoring over a short time interval.
3Measurement precision
If enzyme reaction products are directly measured, then measurement speed is improved, but measurement accuracy deteriorates due to low concentration of organic substances in biological fluids
Solution Approach 1:
The redox substance serves as a signal amplifier and mediator. It accumulates electrons from multiple enzyme reaction events and transfers them to the electrode in measurable quantities. This intermediary system enables detection of very low substrate concentrations by converting tiny amounts of enzyme reaction products into measurable electrochemical signals through the redox cycling process.
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 enables precise measurement of low substrate concentrations with high sensitivity and accuracy by efficiently transferring enzyme reaction charges through the redox substance, maintaining a linear relationship between dV/dt and substrate concentration for real-time monitoring.
Implementation Method 1
a redox substance capable of being reversibly oxidized and reduced, the enzyme and the redox substance being each immobilized onto the working electrode
Data Source
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AI summary
In one aspect, the present disclosure relates to an enzyme sensor (1) for measuring a concentration of a subject substance in a solution containing the subject substance. The enzyme sensor (1) includes: a working electrode (2) and a standard electrode (3) , each of which may be brought into contact with the solution; an enzyme and a redox substance capable of being reversibly oxidized and reduced, the enzyme and the redox substance being each immobilized onto the working electrode (2); and a dV/dt output mechanism (9) capable of outputting, with time, a time differential value dV/dt of a potential difference between the standard electrode (3) and the working electrode (2) caused by changes in concentrations of an oxidized form and a reduced form of the redox substance resulting from a reaction between the subject substance and the enzyme. The potential difference shifts to higher values when the redox substance is oxidized by the reaction between the subject substance and the enzyme, or the potential difference shifts to lower values when the redox substance is reduced by the reaction.