Temperature screening has one primary goal: to identify contagious infection in a person who may or may not be symptomatic. In practice, however, the body’s immune response adds a great deal of complexity to the job of producing a reliable indication of contagiousness. As with any medical device, non-contact thermometers require rigorous testing in order to deliver repeatable, accurate results for every individual screened.
For most products, testing happens only in a lab. This ensures instrument validation: the thermometer reads an object’s temperature accurately. But it does not test the application of the technology: how the thermometer performs on the human body across the broad spectrum of health to infectious disease.
At Wello, we are committed to providing our customers with the most effective health screening solutions on the market. To do so, we’ve adopted a comprehensive testing approach for the welloStationX that includes tests conducted in both laboratory and clinical settings. As a result, our solution produces a proven level of accuracy that supports effective infection control in the workplace.
The challenge of identifying contagious infection
When infection is present, a person’s immune system responds by raising the body’s core temperature to help fight off the invaders. However, there is no way to access this core temperature directly, and every temperature reading technology — mercury, digital, or infrared — acts as a proxy for core temperature. The challenge for thermometers then becomes: how to capture temperature in a way that is the most accurate proxy for body temperature?
The many ways to measure body temperature
Contact temperature readers have long been used on body surface areas that are known to produce reliable evidence of elevated core temperature. That’s why oral, rectal, ear, and armpit readings are standard practice in medical and home settings.
Non-contact temperature screening devices do not have access to body surface areas, so they must take a different approach. Many devices capture readings from the face, and some even use the wrist. When considering the difference, it’s important to understand how heat moves through the body during illness.
Why extremity temperature monitoring doesn’t work
Some non-contact products on the market are designed to measure body temperature by scanning the wrist. These inexpensive devices may be calibrated correctly and work well for a healthy person. But when infection is present, a sick person will get chills and feel cold as the body directs heat inwards. Elevated temperature is not present in the extremities at this point, and temperature readings do not correlate with core temperature when sick.
The face is a reliable source of body heat
Unlike extremities, the face holds heat more consistently as it is closer to the body’s core — just 12 inches from the beating heart. Despite the changing heat patterns throughout the body, the face continues to radiate heat as body temperature rises. Therefore, there are a range of non-contact thermometers available today that capture temperature readings from the face
Facial scanning solutions vary widely
Most facial scanning solutions are camera-based systems that use thermal technology to measure relative temperature over a large area on the face. The result is low quality pixelated thermograph output and a relative temperature reading based on a broad, low density surface area.
Wello, on the other hand, uses infrared technology and precision sensors to produce a clinically accurate temperature reading. Wello sensors zero in on a one-inch target zone in the inner canthus region — the area between the tear duct and bridge of the nose — using 100x-1000x the amount of sensory surface area than thermophile cameras. Learn more about how Wello technology measures elevated temperature.
The laboratory testing approach
A laboratory is an isolated environment with controlled conditions. When testing a sensor’s ability to measure a chemical property like temperature, lab technicians will use something with a known temperature, called a “black body radiator,” as a control. They’ll then point sensors at a target object and measure the accuracy of the reading against the control. WelloStationX lab tests resulted in a range of 0.0 – 0.1 degree Celsius — essentially negligible — variation between readings.
Many thermometer manufacturers will use lab data to adjust the sensors accordingly and then consider the device “tested.” However, lab testing should be only one part of a comprehensive testing strategy that includes clinical data in order to achieve precision readings in the real world.
The clinical testing approach
Lab studies may be rigorous, but they omit a critical factor in temperature screening: the human body. During the course of infection, body temperature changes and a non-contact thermometer needs to be precisely tuned to address these changes. This is only possible when the screening device is tested using human subjects in a clinical setting.
Collecting test data from healthy people as well as sick people is key to ensuring that a thermometer accurately captures elevated temperatures. Because average healthy temperature ranges differ by age and gender, it’s also essential to test the thermometer with a wide range of people. These variants provide a holistic data set that validates the accuracy of a device when used as intended: to identify elevated temperature in humans.
Wello’s clinical study ensures medical accuracy
Given the importance of body temperature monitoring to infection control programs, the team at Wello believes clinical testing is the only way to understand and validate accuracy. During product development, Wello conducted a comprehensive clinical study that validated the accuracy of the welloStationX temperature screening system. The study included:
- A mix of healthy and febrile individuals
- Participants varying by age, gender, and other demographics
- Testing done of the course of a four week period
Temperature readings were captured by both Wello and a Welch Allyn SureTemp oral thermometer (the industry standard oral thermometer) as a reference device. The oral thermometer was read in Extended Mode (three minutes).
The results showed a high level of agreement between readings from both devices with a 0.5 degree Fahrenheit variation. Repeatability across sequential measurements with the welloStationX indicated high precision.
The study concluded that the welloStationX is an accurate and reliable tool to measure body temperature of individuals five years of age and older.