Sample Analysis Method Using Redox Mediator Current
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Solution Overview
Problem
Existing sample analysis techniques based on tunneling current face challenges with sensitivity due to increasing interelectrode distances, as the detectable current becomes extremely small, making it difficult to analyze samples with high sensitivity regardless of electrode distance.
Innovation Solution
A sample analysis method involving a voltage applied between electrode pairs to create an electric field intersecting the sample's migration direction, using an electrochemically active molecule to generate a redox reaction and stabilize the current, allowing for measurement of changes in current that correlate with sample characteristics like volume and charge quantity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between electrodes is increased, then the analytical capability for larger samples is improved, but the detectable current becomes extremely small reducing sensitivity
Solution Approach 1:
The patent introduces an electrochemically active molecule as an intermediary substance in the solution between electrodes. This molecule undergoes redox reactions that generate ionic current, serving as a mediator that amplifies the detectable signal. The ionic current generated by the redox reaction of the electrochemically active molecule provides a strong baseline current that enables detection even when electrode distances are large, thus resolving the contradiction between accommodating larger samples and maintaining detection sensitivity
Solution Approach 2:
The patent changes the fundamental parameter of current generation mechanism from direct electron tunneling to ionic current through redox reactions. By using electrochemically active molecules that undergo oxidation and reduction reactions at the electrodes, the system generates substantial ionic current that is not limited by electrode distance in the same way tunneling current is. This parameter change enables both large sample accommodation and high sensitivity detection simultaneously
2Measurement precision
If tunneling current is used for sample analysis, then direct identification of nucleotides is possible, but the current value becomes extremely small when electrode distance is 2 nm or greater
Solution Approach 1:
The electrochemically active molecule acts as an intermediary that converts the detection mechanism from direct electron tunneling to ionic current measurement. The molecule's redox reactions generate ionic current that flows through the solution between electrodes, providing a strong measurable signal that maintains nucleotide identification capability while overcoming the extreme smallness of tunneling current at distances of 2 nm or greater
Solution Approach 2:
The patent substitutes the electron-based tunneling current mechanism with an ion-based electrochemical current mechanism. Instead of relying on quantum mechanical electron tunneling through the gap between electrodes, the system uses classical electrochemical redox reactions of dissolved molecules to generate ionic current, which is much stronger and more suitable for practical detection at larger electrode separations
3Measurement precision
If high salt or pH solutions are used to enhance current signal, then detectable current increases, but biological samples may be damaged or denatured
Solution Approach 1:
The patent changes the solution composition parameters from high salt or extreme pH conditions to physiological conditions (neutral pH, low salt concentration). The electrochemically active molecules used are specifically selected to function effectively at physiological pH and salt concentrations, enabling strong current signals without compromising biological sample integrity. Examples include ferricyanide/ferrocyanide pairs and other redox-active molecules that operate optimally in physiological buffers
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 high-sensitivity sample analysis regardless of interelectrode distance, stabilizes the current signal, and allows for precise detection of sample characteristics without the need for high salt or pH solutions, suitable for biological samples under physiological conditions.
Implementation Method 1
a solution including an electrochemically active molecule that produces the redox reaction at the first electrode pair
Implementation Method 2
applying a voltage between a first electrode pair, which is formed so as to sandwich a migration pathway of a sample such that an electric field is formed in a direction intersecting the migration direction of the sample
Data Source
AI summary
The analysis method allows analysis of samples with high sensitivity, irrespective of interelectrode distance. The method includes: a step of applying a voltage between a first electrode pair such that an electric field is formed in a direction intersecting a migration direction of a sample; a step of placing a solution, including an electrochemically active molecule that produces a redox reaction at the electrode pair, between the first electrode pair; a step of causing the sample to migrate; and a step of measuring an amount of change in current flow between the first electrode pair.