FET Biosensor Adsorptive Medium for Low Concentration Biomolecule Detection
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Solution Overview
Problem
Conventional field effect transistor (FET)-based biosensors require biomolecules to be immobilized on the gate surface, making it difficult to detect biomolecules at low concentrations and limiting their effectiveness.
Innovation Solution
A device and method using an adsorptive medium with adsorptive sites between the source and drain regions of a modified FET, allowing biomolecules to be non-covalently adsorbed and detected without immobilization, utilizing a voltage to form a channel and measure electrical signals for quantification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If biomolecules are immobilized on the gate surface of the FET, then the FET-based biosensor can measure surface charge density and electric signals, but the detection effectiveness is limited and biomolecules at low concentrations cannot be detected
Solution Approach 1:
The patent introduces an adsorptive medium as an intermediary between the sample and the FET gate surface. This medium contains adsorptive sites that non-covalently bind biomolecules, concentrating them and enabling detection without direct immobilization on the gate surface. The adsorptive medium acts as a mediator that enhances detection effectiveness while expanding the concentration range.
Solution Approach 2:
The patent replaces the mechanical/chemical immobilization system with an electric field-based detection system. Instead of physically fixing biomolecules to the gate surface, the system uses the electric field generated by the FET to detect changes in surface charge density caused by biomolecules bound to the adsorptive medium, thereby expanding detection capabilities.
2Reliability
If biomolecules are fixed to the gate surface, then electric signals can be measured, but the device becomes less reusable and more complex
Solution Approach 1:
The adsorptive medium serves as a removable intermediary that simplifies the device structure. Instead of requiring permanent immobilization layers on the gate surface, the medium can be introduced, used for detection, and then removed or replaced, reducing device complexity and improving reusability while maintaining reliable signal measurement.
Solution Approach 2:
The patent enables the adsorptive medium to be discarded after use or recovered and reused. The medium can be removed from the chamber and replaced with a fresh one, allowing the FET device itself to remain intact and reusable multiple times, thereby reducing overall device complexity and cost.
3Ease of operation
If biomolecules are non-covalently adsorbed on an adsorptive medium, then detection without immobilization is enabled, but additional components are required
Solution Approach 1:
The adsorptive medium is designed to be a universal component that can detect multiple types of biomolecules (proteins, DNA, RNA) through non-covalent adsorption. This multi-functionality reduces the need for different immobilization protocols for different analytes, simplifying the overall detection process despite the additional component.
Solution Approach 2:
The patent utilizes changes in electrical parameters (surface charge density, current, voltage) detected by the FET to indicate biomolecule adsorption on the medium. By monitoring these parameter changes rather than requiring physical immobilization, the system achieves ease of operation with minimal additional complexity.
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 effective detection and quantification of biomolecules, including DNA, RNA, and proteins, even at low concentrations, without the need for pre-immobilization, providing a reusable and efficient biosensing solution.
Implementation Method 1
an adsorptive medium having an adsorptive site on which the biomolecules can be adsorbed
Implementation Method 2
an electrode which applies a voltage to the sample in the chamber, wherein the biomolecules are mobile with respect to the electrode and sample
Data Source
AI summary
A device for detecting biomolecules includes: a semiconductor substrate; a source region and a drain region separately provided at the substrate; a chamber formed at the substrate including a region between the source region and the drain region, the chamber configured to contain a sample including the biomolecules; and an electrode which applies a voltage to the sample in the chamber. The biomolecules are mobile with respect to the electrode and sample. Methods for detecting biomolecules are also disclosed.