Thermostable sensor developed to check fever with smartphone camera

A local research team has developed a thermostable sensor applicable to a smartphone camera to check body temperature.

The research team led by Dr. Choi Won-jun at the Korea Institute of Science and Technology (KIST)’s Center for Optoelectronic Materials and Devices said on Thursday that it developed a new thermal imaging sensor that overcame the problems of the conventional microbolometers.

The new sensor can operate at a temperature up to 100 degrees Celsius without a cooling element, reducing the cost and expanding the scope of temperature, the research team said.

The detector can be applied to smartphones and autonomous vehicles that must operate without problems, even at high temperatures. Smartphone parts should function at 85 degrees Celsius, and autonomous vehicles, at 125 degrees Celsius, without any problem.

The images of the microbolometer (left) developed by researchers at KIST and its schematic diagram (Source: KIST)

To eliminate a cooling element that usually accounts for over 10 percent of the cost and consumes much power, the researchers used a thermally stable vanadium dioxide-B (VO2(B)) film. Then, they made a device that detects infrared rays generated from the heat of VO2(B) film and converts it into an electric signal.

Also, the team developed an absorber that can absorb external infrared rays as much as possible. When used together with the infrared absorber, the microbolometer could detect an object's heat three times more sensitively and convert it into an electric signal.

With a faster response speed, the new microbolometer captured 100 frames per second, compared to 30-40 frames per second by conventional microbolometers, the research team noted.

“With the device technology developed by convergence research, we not only secured the original technology to lower the manufacturing cost of thermal imaging sensors but improve the sensitivity and operation speed,” Choi said.

“We expect that people will increasingly use this technology for thermal imaging sensors in the military industry, smartphones, and autonomous vehicles in the future.”

The study was supported by the Ministry of Science and ICT and a convergence new materials research program jointly by KIST, Ulsan National Institute of Science and Technology (UNIST), and Ulsan City.

The paper, titled, “Wide-temperature (up to 100℃) operation of thermostable vanadium oxide-based microbolometers with Ti/MgF2 infrared absorbing layer for long-wavelength infrared (LWIR) detection,” was published in the latest issue of Applied Surface Science.