Views:109 Author:Site Editor Publish Time: 2019-10-21 Origin:Site
How Does Ear Thermometer Work?
Are mercury thermometers more accurate than electronic thermometers? Of course not! In order to avoid the health damage and environmental pollution caused by the broken mercury thermometer, the World Health Organization proposes to phase out the mercury thermometer in 2020. Mercury thermometer, electronic thermometer, ear thermometer, forehead thermometer, how to choose in so many thermometers?
The electronic thermometer uses the certain relationship between the physical parameters of certain substances (such as resistance, voltage, current, etc.) and the ambient temperature to display the body temperature in digital form, with clear readings and easy to carry.
It is used in a similar way to a traditional mercury thermometer, and is usually measured under the armpit, tongue, or rectum. The disadvantage is that the accuracy of the displayed value is easily affected by factors such as diet, exercise, and measurement duration.
The forehead thermometer mainly depends on the sensor's acceptance of ultraviolet light from the human body to determine the body temperature. It is susceptible to environmental factors such as sweat and room temperature, and is prone to errors, but because it is more convenient to use, it is more used in kindergartens, train stations and other collective places.
Ear thermometer measurement accuracy is relatively high. The ear thermometer's principle is to measure body temperature by detecting the infrared spectrum emitted by the eardrum. The temperature in the ear is closest to the body temperature, and is not easily affected by the external environment and the effects of saliva and sweat. When using an ear thermometer, it is best to take three temperature measurements on the same ear, the highest value is appropriate.
The radiant energy of the human eardrum mainly comes from the 6 ~ 15μm area. Ear thermometers usually use a thermopile sensor. This sensor includes an optical system, a photodetector, a thermopile, and a thermistor. Through the thermopile sensor, it detects the human body's eardrum's far-infrared radiation intensity of 6 ~ 15μm. This measurement is a relative quantity, that is, the result is related to the radiation intensity of the measured object and the temperature of the thermopile itself. The thermistor is used to measure the temperature of the thermopile itself.
The allowable error of the ear thermometer itself is usually ± 0.2 ° C within the range of 36-39 ° C, and ± 0.3 ° C above 39 ° C and below 36 ° C. Improper use can also cause additional errors. Such as a large amount of earwax in the ear canal will cause errors. Because the ear thermometer plugs the ear hole during measurement, the temperature field in the ear hole will change, and the value will change if the measurement time is too long. When repeating multiple measurements, if the measurement interval is not appropriate, the data will be different each time.
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