Graphene SPR Sensor Layout for Selective Low-Concentration Detection
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Solution Overview
Problem
Existing biological and chemical sensors using surface plasmon resonance and graphene transistors suffer from interference due to non-specific target adsorption, limiting their selectivity and sensitivity, especially for low molar mass and low concentration targets, and are restricted to short detection distances.
Innovation Solution
A sensor design incorporating a two-dimensional material layer with specific probes that adsorb specific targets at a distance below a detection threshold, allowing combined electrical and surface plasmon resonance measurements, while keeping non-specific targets outside the detection range, and utilizing a reference transistor for differential measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If functionalisation with specific probes is implemented to improve target detection selectivity, then specific target adsorption is enhanced, but non-specific target adsorption causes interference and degrades detection quality
Solution Approach 1:
The patent introduces a reference sensor as an intermediary element that measures non-specific adsorption effects. The reference sensor is functionalised with the same probes but is used to quantify and subtract the background signal caused by non-specific target adsorption, thereby isolating the specific target detection signal and improving measurement precision.
Solution Approach 2:
The patent implements a feedback mechanism by continuously monitoring both the sensor and reference sensor signals. The system uses the reference sensor's measurement of non-specific adsorption to dynamically correct the main sensor's reading, providing real-time compensation for interference and maintaining high detection accuracy.
2Measurement precision
If detection distance is extended beyond the surface to detect low concentration targets, then detection sensitivity improves, but non-specific targets within the extended range cause interference
Solution Approach 1:
The reference sensor acts as an intermediary that measures the background signal from non-specific targets at the extended detection range. By comparing the main sensor signal with the reference sensor signal, the system isolates the specific target signal even when both specific and non-specific targets are present within the extended detection volume.
Solution Approach 2:
The patent segments the detection function into two independent sensors: one for specific target detection and another for non-specific target measurement. This segmentation allows the system to process specific and non-specific signals separately, enabling accurate detection of low concentration targets while compensating for interference from non-specific targets.
3Measurement precision
If combined electrical and surface plasmon resonance measurements are used to improve detection accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent merges two different detection principles (electrical measurement and surface plasmon resonance) into a single integrated sensor structure. The graphene sheet serves as both the electrical channel and the surface for plasmon resonance, allowing simultaneous measurements without requiring separate devices, thus improving accuracy while limiting complexity increase.
Solution Approach 2:
The graphene sheet performs multiple functions: it serves as the conductive channel for electrical measurements, the surface for surface plasmon resonance, and the functionalisation platform for target adsorption. This multi-functionality allows combined measurements to improve detection accuracy without proportionally increasing device complexity.
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
Enhances target detection sensitivity and selectivity, enabling detection of small-sized, low-concentration targets with improved accuracy by distinguishing specific from non-specific interactions, and expanding the detection range beyond the surface.
Implementation Method 1
This phenomenon results in a decrease in intensity of the reflected light radiation detected at the detector 5 as illustrated in FIG. 2. In FIG. 2, a sharp drop in the relative intensity of the reflected light radiation can be clearly seen for an angle of incidence θi greater than 54°, and which reaches its minimum for the angle of incidence θp, otherwise referred to as the plasmon resonance angle.
Implementation Method 2
A sensor design incorporating a two-dimensional material layer with specific probes that adsorb specific targets at a distance below a detection threshold
Implementation Method 3
characterisation of the electrical properties of transistors suitable for the detection of biological and/or biochemical and/or chemical species
Data Source
AI summary
A sensor may include a prism having a first face; a metal first layer covering, via a contact face, the first face; a light source; and a matrix-array detector; the device may include a dielectric second layer on which rests a transistor including a sheet made of a two-dimensional material, intended to form a channel region, a front face of the sheet comprising a specific functionalization via which specific targets are liable to be adsorbed, the specific functionalization being suitable for placing the adsorbed specific targets at a smaller distance Dd below which detection via electrical measurement by means of the specific transistor and via measurement of resonance of surface plasmons is possible.