Smart fever monitoring system with an IR thermal imager

The COVID-19 pandemic and the action taken to minimise the spread have greatly affected the way we function as a society. This novel coronavirus commonly causes mild to moderate respiratory illness such as fever and cough for most people. However, in vulnerable individuals with a compromised immune system and chronic illness, the infection may progress into severe pneumonia, which can be fatal.

Infrared temperature sensors can be used to detect people with a symptom such as fever and isolate them from the crowd to help minimise the spread of this disease. This is an important system to be implemented in essential operations such as in hospitals, banks, manufacturing sites, process industries, and food and beverage manufacturing which cannot be completely shut down.

The infrared thermal imager generally comes as two different models; a thermal imaging camera or handheld laser thermometer. The handheld laser thermometer is perhaps the more popular of the two, due to its versatility and ease of use by anyone. The operators need to only point the laser to scan the temperature of the person. The thermometer will take the average temperature reading of the spot size and display the value on the device. On the other hand, the thermal imaging camera is capable of scanning the area in the camera’s field of view and look for the hot spot. The thermal imager will display a thermal image of the scanned area and colour-code it based on the temperature reading.

Early detection of symptoms such as fever is essential so that the individuals can be isolated and banned from entering a site. This is to avoid spreading the virus to potentially all employees, which will then require them to self-isolate for at least two weeks. During this period, the factory will have to shut down its operation and suffer losses in this already difficult economic situation.

The application of a thermal imaging camera as a fever monitoring tool can be realised without close contact. This gives the advantage that not many operators are needed to scan each person passing certain checkpoints, and they do not need to risk infection when they are in close contact with someone displaying symptoms.

How to use the thermal imaging camera as a fever monitoring system

The thermal imaging camera can be installed in the entrance of a factory, building or any manufacturing site to scan the body temperature of anyone entering the premises, both staff and visitors. The camera can be used together with an alarm system. When the sensor detects a temperature above a set threshold, such as 38°C and above, it will alert the operator and engineers. This allows them to discreetly approach the person and isolate them from their companions.

Factors to be considered

The accuracy of the infrared temperature measurement highly depends on the emissivity of the target object, the value of which ranges from 0 to 1. Emissivity is defined as the objects’ ability to emit infrared energy. Materials with an emissivity of 1, also known as a ‘blackbody’, do not transmit any infrared energy and they do not naturally exist. Therefore, if the emissivity of the sensor is set to 1, the sensor will return a lower value of body temperature. The emissivity value should be adjusted to that recommended for measuring the temperature of human. From the literature, the emissivity of the human body, skin or organic materials can be estimated as 0.95–0.98.

The placement of the infrared camera is also important to allow a full view of the crowd streaming in and out of the site. In some sites, multiple thermal imaging cameras may be required. The only consideration is to ensure that there are no hot objects present in the view of the camera. Examples of such objects may be machinery with a temperature that may exceed that of the human body or appliances in the kitchen area. These hot objects will cause the alarm system to be non-functional as it will not be able to inform the operators when someone with a fever is captured by the camera.

The MicroEpsilon TIM40 compact thermal imaging camera

At Bestech Australia, we supply the infrared thermal imaging camera from Micro-Epsilon for test, measurement and monitoring applications in industry. Recently, the TIM40 thermal imaging camera has been used for fever monitoring applications for passengers in airports. The feature of this compact thermal imaging camera is its motorised focus function to remotely control the camera focus on specific individual. It also has a good pixel resolution of 382 x 288 pixels with a frame rate of 80 Hz for capturing transient changes in fast thermal processes.

In addition to integration with an alarm function, this thermal imaging camera can also be programmed to provide a snapshot of the infrared images whenever the alarm is triggered. These functions can be written into the software through the integrated software development kit (SDK) that is supplied with the sensor. The temperature monitoring can be done in the control room, away from the crowd, to minimise the operator’s risk of exposure.

Generally, all types of thermal imaging camera are suitable to be used for this monitoring application. The TIM40 has the advantage of a compact design, and is more cost-effective when compared with other TIM thermal imagers from Micro-Epsilon.

For more information, please visit: www.bestech.com.au