FET Biosensor Electrolyte Screening Layer for High-Salinity Sensitivity
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Solution Overview
Problem
Biosensors based on field-effect transistors (FETs) face challenges in sensitivity due to the screening effect of electrolytes, particularly in biological samples with high salinity, which limits their ability to detect target molecules effectively.
Innovation Solution
The introduction of an electrolyte-screening layer that reduces the electrolyte thickness between the FET channel and the target molecule, while maintaining the enzyme's active site uncovered, thereby minimizing electrolyte screening and enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional semiconductor FETs are used, then mass manufacturability is achieved, but sensitivity is low due to electrolyte screening
Solution Approach 1:
The patent segments the enzyme structure into two functional parts: a body that interfaces with the FET channel and an active site that remains exposed to the electrolyte. This segmentation allows the enzyme body to reduce electrolyte screening while the active site maintains its catalytic function, resolving the contradiction between sensitivity and manufacturability
Solution Approach 2:
The enzyme is nested within a protective structure that shields it from electrolyte screening while allowing the active site to remain accessible. The enzyme body is positioned within the FET structure, with only the active site exposed to the electrolyte, creating a nested configuration that simultaneously achieves sensitivity and manufacturability
2Measurement precision
If electrolyte thickness is reduced to minimize screening, then sensitivity is improved, but the enzyme active site may be obscured
Solution Approach 1:
The patent applies local quality by creating different exposure conditions for different parts of the enzyme: the enzyme body is shielded from electrolyte screening to improve sensitivity, while the active site is specifically designed to remain exposed to maintain enzyme activity. This localized differentiation resolves the contradiction between sensitivity and operational effectiveness
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 the development of FET-based sensors with improved sensitivity, enabling effective detection of target molecules in high-salinity biological samples, while also facilitating mass production and low-cost manufacturing.
Implementation Method 1
biosensors based on the detection of a single molecule by an enzyme are currently making use of fluorescence and optical detection... Electrical single molecule sensing of enzyme or protein activity making use of field effect devices (ISFETs, Ion Sensitive Field Effect Transistors) has currently only been reported in a handful of papers
Data Source
AI summary
A sensor is provided. The sensor includes a field effect transistor comprising: an active region comprising a source region, a drain region, and a channel region between the source region and the drain region; a dielectric region on the channel region; an enzyme coupled to the dielectric region, the enzyme having an active site for interacting with a substrate; an electrolyte-screening layer coupled to the dielectric region, covering part of the enzyme while leaving the active site uncovered, thereby permitting interaction of the substrate with the active site, and a fluidic gate region to which the active site of the enzyme is exposed. A biosensing device including one or more of the sensors is also provided.