TIM thermal imager for elevated body temperature detection

22-05-2020

As Australia move into restarting the country post pandemic event, businesses have started to let staff and employees to come in to work. Now that the restrictions have been eased, people have started to flock into public places such as restaurant, shops and shopping centers while still practice social distancing. This is unavoidable as we cannot shut down the country for long period of time. At the same time, we also have to implement screening procedures to ensure that the second wave of virus outbreak can be avoided.

People infected with COVID-19 commonly have fever within 5-10 days of infection, although fever can be attributed to other milder form of illness too. Businesses have definitely considered using thermal imaging camera to identify staff, employees and visitors with elevated body temperature. This has led to surge in demand for thermal imager as non-contact screening tool in the premises.

The TIM-QVGA-HD-T100 thermal imaging camera from Micro-Epsilon is specially developed for the purpose of monitoring elevated skin temperature. The camera works discreetly and can be easily installed and repositioned. The software displays the images of people whose skin temperature exceeds the predefined value and alert the operators. This camera system can be applied in entrance halls & foyers, gates in airports or train stations as well as in hospitals, supermarkets, shopping centers, schools and educational institution.

Measurement principle

This measuring system consists of the TIM-QVGA thermal imager with optional TIM-BR20AR ambient reference detector and a PC. The reference must be positioned in the measuring field of the camera in such a way that the head of the person to be measured is the same distance to the detector. This configuration ensures that measurement accuracy of ± 0.5oC can be achieved with confidence interval of 95%.

In order to achieve reliable measurement results, the skin temperature is taken at the area of the face that approximately correspond to the core body temperature. This spot is called the tear duct of the eyes, which is also referred to as “medial canthus”. It is located in both eyes in the corner next to the nose where the upper and lower eyelids meet. This measurement spot has a diameter of approximately 3mm. It is to be noted that the measurement using thermal imager does not actually reflect the core temperature of human body. Only a medically-certified thermometer can precisely measure the core body temperature.

The benefit of using TIM thermal imager

If the TIM thermal imager cannot accurately measure core body temperature, why it is still be considered as a useful screening tool? The TIM-QVGA thermal imager does not guarantee reliable detection of an infection or illness. It also cannot be relied to provide accurate fever diagnosis. However, the TIM-QVGA thermal imager can effectively detect individual with elevated skin temperature. These people can be isolated and be separately examined by doctors for further diagnosis. Therefore, it avoids the possibility of having the high-risk person entering the premises.

The TIM thermal imager is ideally used for individual temperature measurement. When used for individual measurement, it can measure the temperature of medial canthus and alert the operators in the temperature is elevated. However, it can also be used for screening of crowd or large group. In this case, the TIM thermal imager can detect the elevated skin temperature of individual and isolate the individual for more detailed examination.

Special consideration for accurate measurement

Accurately measuring temperature of human body is tricky and it can be influenced by different internal or external factors. For example, an extremely hot or cold ambient temperature can negatively impact the measurement accuracy. There are several important points to be considered to ensure optimal results from the camera:

  • Ensure that only one person in the camera measuring field
  • Optimal distance of 1m to 1.6 from the camera
  • Camera must be vertically aligned to the visual field
  • The face of the individual must fill more that 50% of the image width to ensure sufficient pixel density of 3×3 pixels for accurate temperature measurement of tear duct
  • The ambient reference detector should be placed at the same distance from the camera as the face to be measured.
  • Accessories such as hats, glasses must be taken off so that eyes are visible

The applications of the TIM-QVGA are not only limited for elevated body temperature screening as the camera can also be used for many measurement applications in the industry. Although it can be represented as early warning system for fever, the TIM camera is not used to reliable detect and isolate individual with coronavirus. There is no infrared camera in the world that can do this. The TIM-QVGA-HD-T100 can reliably measure the temperature difference between the skin temperature and the medial canthus which provides indication of elevated temperature or potential infection. Medical personnel are still needed to confirm whether the isolated person is infected or not. This technology offers the possibility to cut the infection chain in advance.

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