Many types of thermometers have been developed to measure body temperature, Infrared thermometers (IRT) are fast, convenient and ease to use.
Two types of infrared thermometers are used to measure body temperature: tympanic and forehead.
Tympanic means temperature obtained by placing an electronic probe in the ear canal.
With the spread of COVID-19, forehead temperature measurement is used widely to screen people for a high temperature, the performance of this type of device and the criteria for screening are worth studying.
Results showed these infrared thermometers provide good precision, a fixed offset between tympanic and forehead temperature were found. The measurement values for wrist temperature show significant offsets and cannot be used to screen fevers.
Standard operating procedure (SOP) for the measurement of body temperature using an infrared thermometer was proposed. The suggestion threshold for the forehead temperature is 36 °C for screening of fever.
Body temperature of a person who is possibly ill is then measured using a tympanic infrared thermometer for the purpose of a double check.
Body temperature is an indicator of human physiological activity and health.
Most of the early methods of measuring body temperature used contact mercury thermometers. Advances in electrical technology mean that contact-type electronic thermometers have become widely used.
Measurement sites are the mouth, the rectum, the axillary and the base of the urethra. Some medical reports show that contact thermometers accurately measure body temperature to screen for an illness.
Body temperature of many individuals must be measured, so non-contact type infrared thermometers (IRT) are used to measure the tympanic (ear) and forehead temperature.
These IRTs are fast, convenient and safe to use medical IRTs for ear temperature and forehead temperature are used in medicine.
When the temperature of a natural object is higher than the absolute temperature, surface emits thermal radiation, infrared thermometer (IRT) detects this radiant energy that is released by the object via sensing elements and converts it into an electrical signal. After signal processing the measured temperature is displayed on the IRT. this principle is used to develop an IRT to measure body temperature.
In 2003, severe acute respiratory syndrome, which is commonly known as SARS, was prevalent in Asia and caused panic in many countries. IRT is a rapid detection method and the most commonly used IRTs measure temperature of the tympanic and the forehead.
Tympanic is close to the core temperature of the body and gives the most accurate representation of the body temperature, Screening of passengers for signs of Ebola infection was observed with a non-contact thermometer at airports USA in 2014.
IRTs are used to measure the tympanic or forehead temperatures. The probe cover must be changed, and must be adjusted to fit the shape of the ear canal, so measuring the tympanic temperature is a troublesome process.
A forehead IRT is convenient and non-invasive, so any risk of mutual infection is prevented, public places, such as airports, schools, hospital, and transportation vehicles, used this type of device to screen the public in the SARS era.
Surface emissivity of an object has the most significant effect on the temperature that is measured by an IRT. The emissivity of the tympanic membrane is assumed to be 1.0, but the emissivity of human skin is between 0.976 and 0.9.
There are two types of infrared techniques available for the surface temperature detection. One is point estimation to detect the tympanic temperature or forehead temperature, device is called tympanic IRT or forehead IRT.
Measuring the temperature of the forehand using an IRT is convenient, but some studies show that measurements are not accurate. There are three types of forehead thermometer: a thermistor probe, a liquid crystal strip and an IR thermometer. Thermistor probe and the liquid crystal strip are contact-type thermometers, thermistor probe is a deep body thermometer because it is inserted into the tissue of the forehead.
Studies show that a contact-type deep skin forehead thermometer is suited to clinical use, this device was very accurate. This performance of a contact-type forehead thermometer with that of an axillary glass–mercury thermometer found that both thermometers give similar readings.
Liquid crystal thermometers have been used to measure forehead temperature. These studies show that liquid crystal devices are not as accurate as forehead thermistor thermometers and do not give as accurate a reading for core temperature as a rectal or tympanic measurement, esophageal, tympanic and forehead temperature for adults.
The main difference between the esophageal and the forehead temperature was 0.3 °C and the main difference between the tympanic and the forehead temperature was 0.5 °C. forehead temperature was measured using a contact-type, liquid crystalline thermometry strip.
Measuring body temperature is an effective technique for screening SARS and other flus COVID-19 has spread globally and temperature measurement is used to rapidly screen people. Handheld forehead IRTs are easy to use, rapid, non-contact and inexpensive, so they are widely used.
Many studies compare temperature measurements for different parts of the human body using different thermometers. Most of the forehead thermometers are contact-type. Measurements of body temperature depend on the type of thermometer, the sensing elements and the manufacturers’ claimed performance for each thermometer.