Graphene EMI Shielding Layer for Infrared Sensor Arrays
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Solution Overview
Problem
Existing electromagnetic interference protection structures, such as those using Indium Tin Oxide, fail to provide adequate transparency in the infrared spectrum due to absorption of free carriers, leading to interference with read out electronics in sensor arrays exposed to high-intensity radiation.
Innovation Solution
A thin film of graphene is used as an electrically conductive layer between the sensors and the read out electronics, offering high transparency in the visible and infrared spectra while being reflective and dissipative to radio frequency radiation, with a sheet resistivity of less than 100 Ohm/square to ensure effective electromagnetic interference shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If Indium Tin Oxide coating is used for electromagnetic shielding, then RF radiation protection is improved, but infrared transparency deteriorates due to free carrier absorption
Solution Approach 1:
The patent changes the material parameter from conventional Indium Tin Oxide to graphene, which has fundamentally different optical properties. Graphene's unique electronic band structure with zero bandgap energy allows it to maintain high infrared transparency while providing effective RF shielding through its high electrical conductivity and reflective properties.
Solution Approach 2:
The patent employs a composite structure combining graphene layer with the sensor array and readout electronics. This composite material approach leverages graphene's dual properties of high electrical conductivity for RF shielding and high optical transparency for infrared transmission, resolving the contradiction between electromagnetic protection and infrared transparency.
2Object-affected harmful factors
If thicker conductive coating is used to improve RF shielding, then electromagnetic protection is improved, but optical and infrared transparency deteriorates
Solution Approach 1:
The patent changes the thickness parameter to a single atomic layer, which is the thinnest possible configuration. This ultra-thin graphene layer provides sufficient RF shielding through its high sheet resistivity while maintaining excellent optical and infrared transparency, as the absorption remains very low at less than 10% across the spectrum.
Solution Approach 2:
The patent uses a thin film of graphene as the EMI protection layer. This thin film approach allows the material to provide electromagnetic shielding functionality while maintaining high transparency in the optical and infrared regions, as the film thickness is minimized to a single atomic layer.
3Object-affected harmful factors
If highly conductive material is used for EMI shielding, then RF radiation reflection is improved, but infrared absorption increases
Solution Approach 1:
The patent changes the material properties to graphene, which has zero bandgap energy and unique electronic structure. This allows graphene to reflect RF radiation effectively through its high electrical conductivity while absorbing minimal infrared energy, as the absorption coefficient remains very low across the infrared spectrum.
Solution Approach 2:
The patent uses a single atomic layer of graphene that is sufficient for the application. This minimal thickness provides the necessary RF shielding while keeping infrared absorption at acceptable levels, effectively using the minimum required material to achieve the desired protection.
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 graphene layer provides over 90% transparency in the visible and infrared spectra, while dissipating and reflecting greater than 90% of RF radiation, effectively reducing noise and preventing damage to electronics, with a computed electromagnetic shielding efficiency of better than 10 dB.
Implementation Method 1
being reflective and dissipative to portions of the impinging energy outside of the visible and infrared portions of the spectrum
Implementation Method 2
an electrically conductive layer for inhibiting electromagnetic energy outside of the visible and infrared portions of the spectrum
Implementation Method 3
allows optical and infrared radiation to pass through it and impinging onto the sensors behind it
Implementation Method 4
owing to its one layer thickness, the total absorption remains very low. It has been reported in the literature that monoatomic layer graphene films have absorption of ~2.3% in the visible and near infrared
Data Source
AI summary
A detector structure having a sensor for detecting energy impinging on the structure in the infrared and/or optical frequency band; an electronics section disposed behind the sensor for processing electrical signal produced by the sensor in response to the sensor detecting the infrared and/or optical energy; and an electrically conductive layer for inhibiting electromagnetic energy outside of the visible and infrared portions of the spectrum, such electrically conductive layer being disposed between impinging energy and the electronics section, such layer having a transmissivity greater than 90 percent in the visible and infrared portions of the spectrum and being reflective and/or dissipative to portions of the impinging energy outside of the visible and infrared portions of the spectrum. In one embodiment an electrically conductive layer having a substantially constant absorptivity to electromagnetic energy within the visible and infrared portions of the spectrum. In one embodiment, the layer is graphene.