Temperature measurement is one of the important parameters for monitoring a person’s condition. It allows you to detect deviations in time and determine the degree of the immune system’s fight against the infectious pathogen. At the same time, today there are many different options for thermometers that provide results. However, in practice it is noticeable that these readings are not always accurate.
For example, amid the coronavirus pandemic, everyone’s temperature began to be measured on a regular basis. It is a very common phenomenon when measurements are taken when visiting a clinic, some food outlets, etc. Mostly electronic and non-contact thermometers are used for this.
However, to the surprise of many, such devices often show strange values - it has been noticed that when measured with such a thermometer, the readings are usually 35 degrees, or even 34. And this is clearly lower than the standard body temperature of a healthy person. Naturally, many people have questions about whether such measurements can be trusted and why such a discrepancy appears.
What is normal body temperature? More details
Traditional thermometers: mercury and alcohol
Price:
100-200 rubles
The heart of such a liquid thermometer is a thin glass tube, sealed on both sides. At one end of the tube there is a thickening filled with mercury or colored alcohol. Less commonly used are pentane, toluene, carbon disulfide, acetone, and gallium.
There is no air inside the tube. It was pumped out to create a vacuum. This makes it easier for liquids to expand as temperatures change, resulting in more accurate readings.
There is a bottleneck between the tube and the reservoir. This design prevents the mercury or alcohol from moving back after you have taken the temperature. The liquid, of course, will return to its place, but not immediately.
If an alcohol thermometer breaks, you just need to carefully sweep away the fragments. It is more difficult with mercury thermometers.
You need to collect mercury balls by rolling them onto foil or paper. Another option is to collect the drops with a syringe without a needle into a jar of water or a solution of potassium permanganate, close it tightly and take it to a recycling point (usually large clinics have them).
These are the most accurate thermometers you can buy today. No other option, alas, has surpassed these two types of thermometers.
By the way, it was planned to ban mercury thermometers from 2021. But for now you can still find them in pharmacies.
pros
:
- low price
- sold in any pharmacy
- simply measure the temperature of adults
- takes a long time to measure
- fragile
- mercury thermometers are dangerous to break
Minuses
:
Expert opinion
Anton Rodionov, a cardiologist, associate professor of the Faculty of Medicine at the Sechenov Moscow State Medical University, believes that “it’s time to send mercury thermometers to the dustbin of history.” Thermal imagers should be used in crowded places, while electronic devices for measuring body temperature are more suitable for home use.
For the safety of users, preference should be given to thermometers registered as medical devices, since in this case they are subject to mandatory verification before going on sale.
What thermometers do you prefer?
Write in the comments.
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Electronic thermometers
Price
: 300-500 rubles
This thermometer is based on a thermistor. This is a metal sensor whose resistance changes with increasing or decreasing temperature.
The conductor heats up gradually. When the thermometer does not register temperature changes for a certain time, it emits a sound signal.
After the “squeak”, you should hold the thermometer under your arm for another 2-3 minutes. During this time, the temperature may rise by 0.5-1 degrees. In the mouth, the contact with the sensor is tighter, so the temperature is measured faster.
The indicators are digitized and shown on the screen. It is especially convenient if the screen is backlit.
Electronic pacifier thermometers are produced for babies. There are also advanced models that can transfer data to a smartphone or PC.
Typically, electronic thermometers operate on batteries. If the thermometer does not turn on or there is no indication on the screen, check whether it is time to replace the battery.
The most accurate electronic thermometers are with platinum sensors. They allow an error of up to 0.1 degrees Celsius.
But the mass market mainly sells options made of nickel or copper. They are cheaper, but not as accurate.
pros
:
Minuses
:
Review of popular thermometers
Let's consider the characteristics of electronic models for measuring temperature:
| Name | pros | Minuses | Addition |
| B.Well WT-03 Family | 1. Change accuracy 2. Waterproof housing 3. Convenient display 4. Auto shutdown 5. Memory | High price | Manufactured by the Swiss company B.Well |
| AND DT-501 | 1. Replaceable battery 2. Memory 3. Auto power off 4. Waterproof housing 5. Rectal and oral measurement speed - minute | 1. No backlight 2. Small error | The disadvantages are compensated by the low cost of the gadget |
| Thermal Standard | 1. Measurement accuracy 2. Replaceable battery 3. Memory 4. Auto power off 5. Sound signal 6. Measurement speed | 1. Quiet beep 2. No display backlight | The low price compensates for some of the device's shortcomings |
| Omron Eco Temp Basic | 1. Simplicity of the device 2. Sound signal 3. Low price | 1. Large error 2. No backlight 3. Small display 4. Sealed battery | Budget model for the whole family |
| Little Doctor LD-300 | 1. Measuring speed 2. Waterproof housing 3. Replaceable battery 4. Memory 5. Convenient display | 1. Error in readings | The verification measurement must be carried out on the same area of the body, at the same angle of inclination and for the same time. |
Infrared models, comparison:
| Name | pros | Minuses | Addition |
| Xiaomi iHealth Meter Thermometer | 1. Measurement speed 2. Minimum error 3. Distance sensor 4. Backlight 5. Vibration sound signal 6. Multifunctionality 7. Auto shutdown | High price | A universal device for determining the temperature of body, liquid, air |
| Medisana TM 750 | 1. Speed of operation 2. Replaceable battery 3. Backlight 4. Temperature of objects 5. Memory 30 cells 6. Compact body | 1. Contact device 2. Error 3. Complex instructions | The time and date of measurements are stored in memory |
| Sensitec NF-3101 | 1. Non-contact 2. Minimum error 3. Backlight 4. Large memory 5. Replaceable batteries | 1. Does not detect air temperature 2. Sharp sound signal 3. Error in a humid environment | Measures the temperature of objects and water |
| ENDEVER TEMP-03 | 1. High accuracy 2. Auto power off 3. Non-contact 4. Color indication 5. 32 cell memory | 1. Calibration required 2. Display does not light up | Measures the temperature of various surfaces, air and water |
| B.Well WF-1000 | 1. High accuracy 2. Speed 3. Auto power off 4. Large memory capacity | 1. Contact measurement method 2. No backlight 3. Error in a humid environment | The ability to determine the temperature at the temple, in the auricle, on the forehead |
Thermal strips
Price
: 50-100 rubles
Thermal strip, or thermotest, is the ideal thermometer for the road. It is compact, lightweight, and fits in a cosmetic bag or wallet: dimensions are about 2x10 cm, thickness is up to 1 mm.
Typically, thermal strips have large divisions. There are also simpler options: with zones for low, normal and high temperatures.
The basis of the thermal strip is a film coated with a layer of crystal. Crystals change color when exposed to temperature.
Thermal strips are reusable. Measuring the temperature takes 10-15 seconds. Many babies don’t even wake up during this.
But the accuracy of such thermometers is low. The result is influenced by too many factors: from lighting and adhesive density to sweating activity on the skin.
pros
:
Minuses
:
A short reminder about temperature
- By the evening, even a healthy person’s temperature is higher than in the morning.
- Temperature is influenced by emotions, phases of the menstrual cycle, physical activity and even age
- In the elderly, a decrease in temperature to 36.3°C is often observed, while maintaining general good health
- Spasm of skin vessels caused by a febrile state is malignant hyperthermia (“white fever”), requiring emergency medical care and taking emergency measures to reduce body temperature: taking antipyretic drugs and antispasmodics before the doctor arrives. In this case, the body temperature exceeds 40.4°C, cold extremities with general heat, “marbled”, variegated coloring of the skin.
Infrared thermometers
Price
: 2-7 thousand rubles
Infrared thermometers allow you to measure temperature without contact with a person or animal. This speeds up the process and reduces the risk of transmission of infection.
An infrared thermometer measures thermal radiation from the surface of the human body. The working distance of home models is 3-8 cm, thermometers for mass use (industrial pyrometers) “hit” further.
Typically the sensor is placed on the ear or forehead. The process is somewhat reminiscent of scanning barcodes at a supermarket checkout.
At airports, train stations and in transport, infrared thermometers are now used. The result is immediately visible on the LCD screen, so you can quickly identify potentially sick people in a stream of people.
Infrared thermometers can also measure the temperature of surfaces. Or, for example, hot tea or soup.
But the measurement accuracy will vary: from 0.1-0.4 degrees Celsius for human body temperature to 1-3 degrees for other measurements.
Infrared thermometers from well-known medical equipment manufacturers are more accurate than Chinese no-name ones. But gadget manufacturers are also entering the market: for example, Xiaomi with Mi Mijia iHealth.
pros
:
Minuses
:
Thermal cameras for smartphones
Price:
500-5 thousand rubles
Infrared sensors for microUSB, Lightning and 3.5 mm connectors are offered both on Aliexpress and in gadget and accessory stores. Essentially, these are infrared thermometers that measure thermal radiation on the skin and transmit the data to a smartphone.
Typically, price and accuracy of such accessories are closely related. Before purchasing, look for testimonials and reviews of a specific model.
We have already reviewed some of them.
pros
:
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:
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Thermal imagers
Price
: 50-300 thousand rubles, rental - 5-10 thousand rubles per day
A thermal imager is a special device that displays a picture of the temperature distribution over a certain surface. This is clearly not a toy for home use, but a gadget for military and industrial use.
The operation of a thermal imager is based on Planck's law: all bodies whose temperature is above absolute zero emit thermal electromagnetic radiation. The wavelength of radiation and the spectral density of its power depend on body temperature.
The higher the temperature, the shorter the wavelength. Most bodies in the space around us generate maximum radiation in the mid-infrared range: in the range from -50 to +50 degrees Celsius, wavelengths are 7-14 microns.
The thermal imager displays the temperature map on the screen in real time. The color distribution depends on the device settings.
Typically, hot objects are shown in red, cold objects in blue or purple. This is convenient when scanning large spaces: for example, the “reddest” person in the crowd is potentially infected. There are also many models with a black and white screen (white is hot, black is cold).
Theoretically, the real temperature of an object can be masked for a thermal imager. For example, clothing or layers of thermal insulation. This will make it possible to pass off 37.8 degrees Celsius as 36.6, but not hide in the steppe. Although you still have to do something with the face.
pros
:
Minuses
:
Smartphones with thermal imagers
Price:
from 20 thousand rubles
We switch to heavy artillery. In 2014, FLIR released a special thermal imaging case, The FLIR One, for iPhone 5 and iPhone 5S. Cameras were installed in it, and a picture with thermal distribution was displayed on the iPhone screen through an application.
The thermal imager ran on its own battery and even recorded video. The resolution of the thermal imaging camera was 60x80 pixels, and that of the conventional camera was 640x480 pixels. The pictures were combined to obtain a more or less understandable image.
The price of the gadget in the USA is about $350
.
In Russia they offered it more expensively – for 24 thousand rubles
. But now the covers are out of stock.
Later, FLIR, together with Caterpillar, introduced the CAT S60 smartphone with a thermal imager. This is a truly indestructible tank that does the job well. Price – from 25 thousand rubles
, but you will have to look for available options.
There are also Seek Thermal Compact and Compact Pro thermal imaging attachments. These are accessories for the Lightning or microUSB connector that turn any smartphone into a thermal imager. The power, of course, is much lower than that of military models, but the price also starts from 20 thousand rubles
.
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:
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