Scientists explain how your next thermometer might be in your phone

12th August, 2021.      //   Health  // 


Body temperature checks have become standard practice for anyone entering public venues such as hospitals, office buildings, and airports as a result of the COVID-19 pandemic. Visitors pass through checkpoints one by one as staff aim hand-held laser equipment at each person’s forehead to check for fever.

Some institutions, such as the US Department of Defense, have upgraded to thermal imaging cameras to speed up the procedure. These cameras allow for a faster flow of traffic into facilities and greater social separation between checkpoint staff and visitors. Thermal imaging cameras, on the other hand, are still not commonly employed due to their high cost, which is largely due to expensive cooling components.

Researchers in South Korea have created a microbolometer, a new, low-cost heat-detecting sensor that might make thermal imaging cameras more accessible by embedding them into smartphones. The new microbolometer can work accurately at temperatures of 100 degrees Celsius (212 degrees Fahrenheit), which is essential because running at 85 degrees Celsius (185 degrees Fahrenheit) is a requirement for smartphone components that must withstand periods of heating and cooling. In May, the findings were published in the journal Applied Surface Science.

Noncontact thermometers convert infrared radiation, which is emitted by all objects with a temperature above absolute zero, into electrical energy, which is presented as a temperature in Fahrenheit or Celsius. The amount of infrared radiation emitted by an object increases as its temperature rises. The red or green laser on your forehead is only there to help you point the gadget in the appropriate direction; it has no bearing on the actual measurement.

Many microbolometers make up thermal imaging cameras, which sense temperature in a different, far more sensitive way than noncontact thermometers. The flow of electrical current through a certain type of detector material changes when infrared light heats it up. This difference is then converted to a temperature reading.

The most common microbolometers can only operate at or near room temperature, necessitating the need of a separate cooling device in high-temperature situations. Choi and his colleagues developed a vanadium dioxide film that could demonstrate the same changes in electrical current from room temperature to 100 C, replacing the standard detector material with a more heat-stable one (212 F).

They also included an infrared absorber in the microbolometer, which boosted the device’s sensitivity by a factor of three by maximizing the device’s intake of infrared radiation. Even at 100 degrees Celsius, the microbolometer was able to collect thermal images at 100 frames per second, which is three to four times faster than conventional sensors.

Most bolometer manufacturers now have suggested technology that can function at high temperatures such as 85 C, according to Arnaud Crastes, a business development director at Teledyne Image, a consortium of technological firms that make imaging sensors.

Thermal imaging cameras based on low-cost, high-temperature microbolometers might be used for night vision, identifying dangers in cars, detecting structural problems in structures, and assisting firefighters in seeing through smoke.

“Uncooled thermal imagers were originally developed for military applications, such as the remote temperature sensing of military objects or soldiers,” said Won Jun Choi of the Korea Institute of Science and Technology’s Center for Opto-Electronic Materials and Devices, the study’s lead author. “But now, many other kinds of applications are possible.”

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