Graphene Biosensor Linker Layer for Conductivity and Selectivity

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Solution Overview

Problem

Existing graphene transistors face limitations in surface modification due to degradation of electrical conductivity and structural stability, leading to reduced selectivity and sensitivity in biosensors, and require complex multi-step processes that increase fabrication costs.

Innovation Solution

A biosensor using a graphene transistor with a linker layer composed of an N-heterocyclic carbene compound that allows for direct covalent binding of a bioprobe unit without additional chemical reactions, enhancing electrical conductivity and stability while simplifying the fabrication process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If covalent functionalization method is used to modify graphene surface, then stability of transistor against ions in solution is improved, but electrical conductivity is degraded

Engineering Contradiction:

Improvestability of transistorVSAvoidelectrical conductivity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by functionalizing only specific regions of the graphene surface rather than the entire surface. The linker layer is formed at controlled locations to provide stability while preserving the bulk electrical conductivity properties of the graphene channel.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure by combining graphene with a linker layer formed from N-heterocyclic carbene compounds. This composite approach allows the system to exhibit both the electrical conductivity of graphene and the chemical stability of the organic linker layer.

Inventive Principle:

Principle #40Composite materials

2Reliability

If covalent functionalization method is used to modify graphene surface, then selectivity and sensitivity of biosensor are improved, but structural stability is degraded

Engineering Contradiction:

Improveselectivity and sensitivityVSAvoidstructural stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces a linker layer as an intermediary between the graphene surface and the bioprobe unit. This intermediate layer maintains the structural integrity of graphene while providing functional groups for bioprobe attachment, thus preserving both sensitivity and structural stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If multi-step process is used for surface modification and bioprobe attachment, then functionality is improved, but fabrication complexity is increased

Engineering Contradiction:

ImprovefunctionalityVSAvoidfabrication process

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the surface modification step and the bioprobe attachment step into a single integrated process. The linker layer formation simultaneously prepares the surface for bioprobe attachment and provides the functional interface, eliminating the need for separate modification and attachment steps.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent performs preliminary action by pre-forming the linker layer on the graphene surface before bioprobe attachment. This preliminary functionalization creates a ready-to-use interface that simplifies the subsequent bioprobe attachment process and reduces overall fabrication complexity.

Inventive Principle:

Principle #10Preliminary action

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 biosensor achieves improved sensitivity and stability by maintaining graphene's intrinsic electrical conductivity and simplifying the fabrication process, reducing costs and complexity.

Implementation Method 1

the carbene group covalently bonds to graphene of a graphene channel layer through self-bonding

Methodology Applied

Scientific EffectCovalent bonding: Chemical Bonding

Implementation Method 2

the graphene transistor has an excellent advantage in that it shows very high charge mobility because the effective mass of electrons is 0 due to the ballistic electron transfer

Methodology Applied

Scientific EffectBallistic electron transfer:

Implementation Method 3

degraded uniformity and dispersibility by Van der Waals forces acting between graphene layers

Methodology Applied

Scientific EffectVan der Waals forces: Van der Waals Force

Data Source

PatentEP3703134B1Biosensor comprising graphene transistor functionalized with n-heterocyclic carbene compound and fabrication method therefor

Publication Date: 2024.04.17 KOREA RES INST OF BIOSCIENCE & BIOTECHNOLOGY

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AI summary

The present invention relates to a graphene transistor comprising: a substrate; a graphene channel layer arranged on the substrate; a pair of metals spaced from each other and respectively arranged at opposite ends of the graphene channel layer; and a linker layer arranged on the graphene channel layer and including an N-heterocyclic carbene compound, a fabrication method therefor, and a biosensor comprising the same. The graphene transistor according to the present invention in which the carbene group of the N-heterocyclic carbene compound forms a covalent bond with the graphene channel layer to modify the whole surface of the graphene channel layer exhibits excellent electric conductivity as a transistor and a biosensor comprising the transistor is improved in selectivity and sensitivity.