Why in News

• Researchers at Jamia Millia Islamia, New Delhi, have developed an ultrasensitive quantum thermometer using graphene quantum dots. The thermometer can measure micro Kelvin changes in temperature and has quick response time.

Sensitive device

• The thermometer can precisely measure a wide range of temperature: 27 degree C to –196-degree C. The thermometer has high sensitivity when measuring different temperatures and can measure very minute (micro Kelvin) changes in temperature.
• The thermometer also showed extremely quick response time of just about 300 milliseconds to register a change in temperature from 27 degree C to –196-degree C. And the time taken to return to its initial temperature value was as little as about 800 milliseconds.
• The thermometer showed excellent repeatability with negligible variation in sensing response when tested for over 50 cycles during a one-year period. The device can find widespread applications in cryogenic temperature sensing.
• Since the sensor has high sensitivity and ability to measure minute changes in temperature, it will be useful in the pharmaceutical industry, healthcare to measure the incubation temperature of biological cells and molecules and the automobile industry to measure the ignition temperature within the engine.
• The sensor can also be used for measuring high temperatures up to 100-degree C. Compared with low temperature, the high-temperature sensitivity is low but it is still much higher than currently available solid-state thermometers in terms of sensitivity, resolution, response and recovery timings,

Sensor Preparation

• The researchers first prepared graphene oxide and chemically made it reduced graphene oxide. “The physical and chemical properties of reduced graphene oxide are very close to monolayer graphene.
• So by using reduced graphene oxide it is easy to synthesise in large-scale materials having properties similar to graphene,”
• The synthesis process is extremely cost effective, has high yield and batch fabrication is possible. One of the main advantages is that this device can be made to any shape and dimension,” Scientists are working on making a prototype of this thermometer to be used in electronic devices, as on-chip thermometers that do not even require calibrations. they will replicate these achievements in single electron transistors (SETs) to miniaturise it for integration in integrated circuits.

Quantum thermometer

• The problem of normal thermometers are not accurate. They need to be calibrated, or adjusted, to some standard. To use the beam as a thermometer, researchers must be able to measure the tiniest possible vibrations in the beam. The amount that the beam vibrates is proportional to the temperature of its surroundings.