Electrochemical Extended-Gate Transistor for High-Ion Fluid Detection
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Solution Overview
Problem
Conventional FET-based biosensors face challenges in detecting biomarkers in high-ion fluids due to the neutralization of electric potential by ions, leading to reduced detection limit and sensitivity, as the Debye length is shortened, making it difficult to accurately measure biomarker concentrations in high ionic strength environments.
Innovation Solution
An electrochemical extended gate FET-based system (EET) is developed, which uses a potentiostat with a working, counter, and reference electrode to generate redox signals in an ion fluid, allowing for the detection of targets like biomarkers, even in high-ion fluids, by modifying the detection region with recognition elements and potentially using mediators to enhance signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional FET-based biosensor is used in high-ion fluid, then the structure is simple and operation is straightforward, but the detection sensitivity and limit are reduced due to shortened Debye length
Solution Approach 1:
The patent merges the electrochemical cell (with working, counter, and reference electrodes) with the FET biosensor into an integrated system. The gate electrode of the FET serves as the working electrode, combining the electrical sensing function with electrochemical detection capability. This integration allows the system to overcome the Debye length limitation in high-ion fluids while maintaining a relatively compact structure.
Solution Approach 2:
The patent introduces an electrochemical mediator system where redox reactions occur at the gate electrode surface. The electrochemical signals generated by these reactions serve as intermediaries to detect biomarker binding events, bypassing the limitation of direct electrical potential measurement that is screened by ions in high-ion fluids.
2Measurement precision
If sample dilution is performed to extend Debye length, then detection sensitivity improves, but the target biomarker concentration is further reduced limiting practical application
Solution Approach 1:
The patent changes the detection parameter from direct electrical potential measurement to electrochemical signal measurement. By measuring current or potential changes resulting from redox reactions at the electrode surface, the system can detect biomarkers in high-ion fluids without requiring sample dilution, thus maintaining the original biomarker concentration.
3Measurement precision
If multiple pretreatment processes are applied to remove ions, then detection sensitivity improves, but the process complexity and time consumption increase
Solution Approach 1:
The patent extracts the electrochemical detection function from the conventional FET biosensor framework. By incorporating a complete electrochemical cell with working, counter, and reference electrodes, the system directly detects biomarkers in high-ion fluids without requiring the extraction or removal of ions through complex pretreatment processes.
4Adaptability or versatility
If conventional EC system is used for detection, then Debye length issue is resolved, but the detection sensitivity is poor for low concentration targets
Solution Approach 1:
The patent combines the advantages of FET-based electrical detection with electrochemical detection. The FET's high sensitivity to electrical changes is leveraged to detect the small current changes resulting from electrochemical reactions, thereby achieving both the ability to work in high-ion fluids and the sensitivity required for low-concentration target detection.
Solution Approach 2:
The patent replaces the conventional electrochemical measurement system with a FET-based electrical measurement system. The FET acts as a transducer that converts the electrochemical signals (current changes at the electrode) into measurable electrical signals with high sensitivity, eliminating the need for complex conventional EC measurement equipment while improving detection sensitivity.
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 EET system significantly improves detection sensitivity and limit by extending the Debye length, enabling accurate detection of biomarkers at lower concentrations, with a detection limit at least 30 times greater than conventional EGFET systems and 100 times greater than conventional EC systems, while maintaining flexibility in measuring targets with or without electrochemical activity.
Implementation Method 1
An electrochemical (EC) system can serve as a solution to resolve the issue of Debye length by providing EC signal for detection
Implementation Method 2
the charges of the biomarkers 154 will accumulate on the gate surface to cause a potential on the gate 150, such that the biomarker concentration can be determined by the current flowing through the substrate 120
Implementation Method 3
once the distance (r) between the gate surface and the caught biomarker exceeds a specific length (FIG. 1(B)), i.e. Debye length (λ) over which the ions in the sample screen out electric potential of caught biomarkers
Data Source
AI summary
An electrochemical extended-gate transistor (EET) system is provided, the system includes: a field effect transistor (FET), having a gate, a source, and a drain; a potentiostat, having a working electrode, a counter electrode, and a reference electrode; wherein the working electrode is coupled with a detection region, and the counter electrode is coupled with the gate; wherein the detection region, the gate, and the reference electrode are arranged in an ion fluid; wherein the potentiostat is configured to generate redox in the ion fluid by an electrochemical method to detect the target. A method for detecting targets are used to such system.