Suspended Graphene Nanopore Sensor for Differential Tunnel Current Detection
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Solution Overview
Problem
Current single-molecule sequencing technologies face challenges such as thick biological nanopores affecting spatial resolution, instability, and limited scalability, as well as low signal-to-noise ratios and clogging issues in ionic current detection methods.
Innovation Solution
A differential suspended single-layer graphene nanopore sensor is developed, featuring etched silicon substrates with suspended graphene strips and metal electrodes, allowing for precise nanopore formation and differential current measurement, enhancing spatial resolution and signal intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If biological nanopores are used for sequencing, then detection capability is achieved, but spatial resolution deteriorates due to pore thickness being much greater than distance between adjacent bases
Solution Approach 1:
The patent transitions from biological nanopores with thickness of 3-8 nm to single-layer graphene nanopores with thickness of 0.34 nm, changing the material parameter to achieve atomic-level thickness that matches the 0.34 nm distance between adjacent DNA bases, thereby resolving the spatial resolution limitation
Solution Approach 2:
The patent employs single-layer graphene as a composite material that combines the nanopore function with ultra-thin atomic structure, creating a material that is both mechanically stable and thin enough to provide high spatial resolution for single-base detection
2Reliability
If phospholipid bilayer is used, then biological nanopore function is achieved, but stability and reliability deteriorate due to lack of tolerance and limited service life
Solution Approach 1:
The patent replaces the unstable phospholipid bilayer with single-layer graphene, which provides long-term stability and reusability, eliminating the need for frequent replacement and improving device reliability for clinical applications
Solution Approach 2:
The patent uses single-layer graphene specifically at the nanopore region where mechanical strength and stability are most needed, while maintaining the biological functionality of the nanopore, achieving local optimization of material properties
3Measurement precision
If ionic current detection method is used, then sequencing is achieved, but signal-to-noise ratio deteriorates due to low signal amplitude
Solution Approach 1:
The patent replaces the ionic current detection method with tunnel current detection through the single-layer graphene nanopore, substituting a mechanical/electrochemical system with a quantum mechanical effect-based system that provides higher signal amplitude and better signal-to-noise ratio
Solution Approach 2:
The patent changes the detection mechanism from ionic current (order of 1 nA) to tunnel current through graphene, altering the physical parameter of current type to achieve significantly enhanced signal amplitude and improved detection precision
4Reliability
If single-pore ionic current measurement is used, then sequencing is achieved, but reliability deteriorates due to pore clogging and device failure
Solution Approach 1:
The patent divides the detection system into multiple independent nanopores in an array configuration, so that clogging of one pore does not affect the overall device functionality, maintaining reliability through parallel operation of multiple segments
Solution Approach 2:
The patent uses single-layer graphene nanopores that are resistant to clogging and can be easily replaced or regenerated, treating the nanopore structure as a durable component that maintains functionality over extended use periods
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 solution achieves high spatial resolution, improved signal-to-noise ratios, and increased throughput, overcoming existing nanopore technology bottlenecks to reach clinical application standards for sequencing precision.
Implementation Method 1
punching nanopores in one of the two single-layer graphene strips suspending in the at least one groove by using an ion beam
Implementation Method 2
improve signal intensity by detecting a tunnel current
Data Source
AI summary
Provided is a preparation method for a differential suspended single-layer graphene nanopore sensor. The method includes: forming a SiO2 layer on a silicon substrate layer, and etching a side of the silicon substrate layer facing away from the SiO2 layer to form a groove; forming a graphene strip unit on the SiO2 layer, the graphene strip unit including two single-layer grapheme stripes arranged at an interval and stretched across the groove; depositing a metal electrode layer, the electrode layer formed at one side of the groove covering the two single-layer grapheme stripes simultaneously, the electrode layer formed at another side of the groove including two parts arranged at an interval and each covering one of the two single-layer graphene strips; etching away the silicon dioxide layer that is exposed in the region of the groove; and punching nanopores in one of the two single-layer graphene strips suspending.