FET Bio-molecule Detection Without Probe Immobilization
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Solution Overview
Problem
Conventional field effect transistors (FETs) used for bio-molecule detection require immobilizing probe bio-molecules on the gate surface, which complicates the process, increases response time, and leads to variations in sensor properties, making them difficult to use in lab-on-a-chip applications and requiring disposal after each use.
Innovation Solution
A method using a field effect transistor with a semiconductor substrate and an insulating layer on the channel region, where bio-molecules directly contact the sensing surface without immobilization, allowing for continuous detection by measuring changes in electric signals, and the surface is washed between samples to maintain sensor functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If probe bio-molecules are immobilized on the gate sensing surface, then the detection of target bio-molecules is enabled, but the manufacturing process becomes complex and response time increases
Solution Approach 1:
The patent removes the probe bio-molecule immobilization step from the FET sensor structure. Instead of fixing probes on the gate surface, the invention uses the gate electrode itself as the sensing surface that directly interacts with target bio-molecules in the sample, thereby extracting and eliminating the complex immobilization process while maintaining detection capability
Solution Approach 2:
The gate electrode serves multiple functions: it acts as both the electrical control element of the FET and the sensing surface for bio-molecule detection. This multi-functionality eliminates the need for separate probe molecules and their associated immobilization processes, simplifying the overall device structure
2Reliability
If probe bio-molecules are fixed on the gate surface, then target bio-molecule detection is achieved, but response time increases and continuous use is prevented
Solution Approach 1:
The FET sensor enables continuous detection by allowing the gate electrode to repeatedly interact with different samples without requiring probe re-attachment. The sensing surface remains ready for immediate use after washing, enabling continuous or repeated measurements without the time loss associated with probe immobilization and binding steps
3Reliability
If probe bio-molecules are immobilized on the gate surface, then detection is enabled, but sensor properties vary between devices
Solution Approach 1:
The invention extracts and removes the variable immobilization step that caused property variations. By using the gate electrode surface directly without probe molecules, the sensing mechanism becomes intrinsic to the device structure itself, eliminating the variability introduced by different immobilization conditions and probe configurations
4Reliability
If probe bio-molecules are used, then detection is possible, but the sensor must be disposed of after each use
Solution Approach 1:
The invention eliminates the need to discard the sensor after each use by removing the consumable probe molecules. The gate electrode sensing surface can be washed and reused for subsequent detections, transforming the sensor from a single-use device to a reusable one, thereby improving productivity
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 continuous, rapid, and accurate detection of bio-molecules without the need for probe immobilization, reducing sensor variability and allowing for repeated use, thus simplifying the manufacturing process and improving detection efficiency.
Implementation Method 1
a field effect transistor without fixing probe bio-molecules on the gate sensing surface
Implementation Method 2
measuring a change in electric signal of the field effect transistor
Data Source
AI summary
A method of detecting a presence of bio-molecules, or a concentration of the target bio-molecules using a field effect transistor, includes allowing a first sample including a first target bio-molecule to contact a sensing surface of the field effect transistor and measuring a change in an electric signal of the field effect transistor, the field effect transistor including a substrate, a source region and a drain region, the source region and the drain region formed apart from each other on the substrate, the source region and the drain region each doped to having an opposite polarity than a polarity of the substrate, a channel region disposed between the source region and the drain region and an insulating layer including the sensing surface, the insulating layer disposed on the channel region.