[China Instrument Network Instrument Development] Graphene combined with thermoelectric materials can detect extremely weak temperature changes.
Researchers at the Cambridge Graphene Center have discovered that the use of graphene with unique electrical properties as a sensor for thermal imaging can greatly improve the thermal imaging quality. Combined with a thermoelectric material that converts temperature changes into electrical signals, this graphene-containing sensor senses temperature changes of several tens of micro K. In practical applications, this HD thermal imaging technology is expected to provide more accurate detection methods for the detection of explosives and other harmful substances.
The study was published in Nature News. The paper mentioned that the researchers placed a layer of graphene on the thermoelectric material matrix lithium niobate (LiNbO3) and placed an electrode (usually made of gold) called "floating gate" on it. The floating gate electrode concentrates the electric field generated by the temperature change in the thermoelectric material in the graphene, thereby changing the resistance of the graphene, and the change of the graphene resistance is the output result of this device. Resistive bolometers use this principle. Researchers believe that sensors using thermoelectric materials and resistive bolometers can provide the necessary pixels for high-definition thermal imaging cameras.
One of the biggest advantages of using graphene is that you can use it as a built-in thermoelectric signal amplifier. Traditional infrared sensors require the use of transistors to amplify thermoelectric signals generated in thermoelectric materials. The disadvantage is that this process will lose the signal or generate noise, which in turn reduces the sensitivity of the sensor. With graphene, the thermoelectric signal goes directly into the graphene and is enlarged. “When a graphene amplifier is placed on a thermoelectric material, the current change generated by the thermoelectric material will directly enter the graphene without any loss,†explains the author Alan Colli. Dr. Colli works for Emberion, which split from Nokia last year to develop X-ray, thermal, and infrared camera sensors. The two companies are cooperative in this research.
In addition, the graphene's electrical conductivity also allows the sensor to be connected in series with an external read line, ensuring that the sensor signal's transmission efficiency is as high as possible.
This graphene-based sensor can detect temperature changes that are 1000 times smaller than the temperature change caused by a person's hand, and is capable of resolving temperature changes as low as 15 μK. This is the sensitivity reported in graphene-based uncooled thermography detectors. Highest. This high sensitivity means that it can even be used in spectroscopic analysis to detect the narrow infrared spectrum emitted or absorbed by certain chemical functional groups, which is not what traditional infrared detectors can handle.
Increased sensitivity means that the detector can reduce the range of detectable radiation frequencies while maintaining high image resolution and can help identify specific substances that emit or absorb very narrow spectral features, such as explosives, toxic substances and other dangerous goods. , improve the accuracy of security.
(Original Title: Graphene HD Thermal Imaging Technology Easily Detects Explosives)
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