Single FET Bio-molecule Detection via Signal Comparison
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Solution Overview
Problem
Conventional field effect transistors (FETs) used for bio-molecule detection face inaccuracies due to variations in manufacturing, leading to unreliable noise signal assumptions between reference and sensing FETs, which affects the accuracy and sensitivity of bio-molecule detection.
Innovation Solution
A method using a single field effect transistor to detect bio-molecules by measuring electric signal changes from samples with and without target bio-molecules, without immobilizing bio-molecules on the transistor, and comparing these signals to determine presence and concentration, utilizing a substrate with separate source and drain regions, an insulating layer with a sensing surface, and a reference electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple FETs are used for bio-molecule detection with reference and sensing configurations, then detection sensitivity can be improved, but manufacturing variations cause unreliable noise signal assumptions and reduce measurement accuracy
Solution Approach 1:
The patent combines the reference and sensing functions into a single FET device. The gate electrode serves dual purposes: as a reference surface for noise signal measurement and as a sensing surface for bio-molecule detection. This merging eliminates the reliability issues caused by manufacturing variations between separate FETs, while maintaining detection sensitivity through sequential measurement of reference and sample solutions on the same device.
2Measurement precision
If multiple FETs are used to differentiate signal from noise, then detection sensitivity improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The gate electrode is designed to perform multiple functions: it serves as both a reference surface for measuring noise signals and as a sensing surface for detecting bio-molecules. By making the gate electrode universal, the patent reduces the number of FET components needed from multiple devices to a single multi-functional device, thereby reducing device complexity and manufacturing cost while maintaining the ability to differentiate signal from noise.
3Measurement precision
If bio-molecules are immobilized on the gate surface for detection, then detection sensitivity improves, but manufacturing complexity and process steps increase
Solution Approach 1:
The patent employs a dynamic detection approach where the gate electrode alternates between measuring reference solutions and sample solutions, rather than requiring static immobilization of bio-molecules. This dynamic method allows the same gate surface to serve both reference and sensing functions sequentially, eliminating the need for complex immobilization processes while maintaining detection sensitivity through comparative measurement.
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
This approach allows for accurate and efficient detection of bio-molecules without the need for immobilization, reducing manufacturing complexities and enhancing sensitivity by comparing electric signals from the same transistor for both samples, thereby overcoming the limitations of conventional FET bio-sensors.
Implementation Method 1
a field effect transistor which includes a substrate 21 composed of a semiconductor material; a source region 22a and a drain region 22b which are formed to be separate on the substrate 21 and doped to have the opposite polarity to the substrate 21; a channel region disposed between the source region 22a and the drain region 22b; an insulating layer 23 which is disposed on the channel region and has a sensing surface 23a; and a reference electrode 24 disposed above and to be separate from the insulating layer 23
Data Source
Figure 1A~1B
Figure 2~3
Figure 4A~4B
AI summary
Provided is a method of detecting the presence of a target bio-molecule or a concentration of the bio-molecule using a field effect transistor. The method includes: providing a first sample having a first target bio-molecule to a sensing surface of a field effect transistor and measuring a first electric signal change of the field effect transistor; providing a second sample to the sensing surface of the same field effect transistor and measuring a second electric signal change of the field effect transistor; and comparing the first electric signal with the second electric signal, wherein the field effect transistor includes: a substrate composed of a semiconductor material; a source region and a drain region which are formed to be separate on the substrate and doped to have the opposite polarity to the substrate; a channel region disposed between the source region and the drain region; an insulating layer which is disposed on the channel region and has the sensing surface composed of an electrically insulating material; and a reference electrode disposed above and to be separate from the sensing surface of the insulating layer.