At present, we are fighting a stealth monster called new crown epidemic (COVID-19), and we are experiencing our greatest health crisis in this era due to the sharp increase in infection. One of the main symptoms of COVID-19 infected people is that there is an increase in body temperature, and there are other symptoms, such as physical pain, difficulty breathing.
Continuous monitoring of body temperature is very important to find patients in early days to take appropriate drug treatment to quickly rehabilitate.
Ordinary infrared thermometers can measure the body temperature of new crown, or may also spread viruses. The main disadvantage of the hand-held thermometer is that its performance depends on the distance from the operator's forehead.
In order to solve these problems, I designed a device that can be installed on the wall for a fever screening in the public area without an operator. When the distance between the sensor and the forehead is sufficient, the hardware can automatically measure the human body temperature.
Video tutorial:
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statement:
The main inspiration source from the IThermowall project, I will fully thank the author of the project.
I think this project is very useful in this critical moment, I can use my skills to write a DIY guide, including accurate explanations and exquisite illustrations, so that anyone can easily recreate it.
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The required components:
Arduino nano
2. GY-906 temperature sensor
3. OLED display
4. Infrared proximity sensor
5. TP4056 charger module
6. 18650 battery
7. 18650
8. 5 V DC-DC boost converter
9. Strip switch -15 × 21 mm
10. 5mm green LED
11. 5mm red LED
12. Jumper
Tool list:
Soldering iron
2. Line cutting machine
3. Stripper clamp
4. 3D printer
Step 1: Working principle Description
The working principle is very simple, and the infrared temperature sensor MLX90614 reads the human body when the distance between the forehead and the sensor matches the set value. The sensor reading is sent to Arduino for processing, and the process is displayed on the 0.96 "OLED display.
In addition to the OLED display screen, two LEDs and a buzzer are also used to indicate the output.
1. When the body temperature is normal, the green LED (LED1) is on, and the buzzer is called.
2. When the body temperature is higher than 104 degrees, the red LED (LED2) will illuminate and the buzzer will make a long time.
Step 2: Power supply
The power required for the entire circuit is provided by two 18650 batteries. Two batteries are connected in parallel to make higher capacity battery packs to achieve longer backup time. The battery pack is charged by the TP4056 charger module.
The battery pack voltage is raised to 7V using the boost converter module (MT3608). Then the boost converter is connected to the VIN pin of Arduino.
A rocker switch is placed between the charger module TP4056 output and the boost converter.
Step 3: Prepare Arduino and Temperature Sensors
To reduce costs, manufacturers typically send you a circuit board and connector pins, but I hope you will be welded to board. I received Arduino NANO and MLX 90614 sensors, but there was no solder joint.
To connect the needle pin to the board, first place the pin on the breadboard. This is optional, but this is a good way to ensure that the pin is perpendicular to the board and parallel to each other, so that the board can easily insert the board in other places. Place the circuit board at the top of the joint, the pins pass through the holes on the board.
Use a fine soldering iron because you will use small parts close together. The welding result should be a cone solder covering the circular pad and the bottom of the pin. There should be no solder to connect two pins together.
Step 4: MLX90614 Infrared Temperature Sensor
MLX90614 is an infrared thermometer for non-contact temperature measurement, which can measure the temperature between -70 to 380 ° C. The sensor uses an infrared sensitive thermoelectric stack detector chip and signal adjustment ASIC integration in a single chip. It works based on Stefan-Boltzmann's law, which points out that all objects will emission IR energy, and the strength of the energy will be proportional to the temperature of the object. The sensor is measured with how much infrared energy emitted in the target object, and the computing unit converts it to a temperature value using a 17-bit built-in ADC and outputs data through the I2C communication protocol.
The sensor measures the temperature and ambient temperature of the object to calibrate the temperature of the object. The MLX 90614 sensor can read the temperature of the ambient temperature in the range of -40 to 125 ˚c (-40 to 257 ° F) and the object temperature in the range of -70 to 380 ˚C (-94 to 716 ° F).
The infrared thermometer and Arduino are very simple because it uses the I2C communication interface like many other components.
The MLX90614 thermometer has 4 pins: VIN, GND, SCL, and SDA.
The connection should be as follows:
Arduino -. 1882. MLX 90614
5V ---. 1882. VIN
Land -. 1882.
A5 ----. 1882. SCL
A4 ----. 1882. SDA
Step 5: Prepare the battery pack
We must parallel the two 18650 batteries. I have used the battery slot is a two-slot, with separate terminals for connection. To do parallel, use a wire to connect two terminals on each side together.
First apply a small amount of flux on the terminal, then use the wire to short the way.
Next, the red extension line is welded to the positive terminal, and the black wire is welded to the negative terminal of the battery holder.
Step 6: Infrared proximity sensor
Currently, hand-held thermometers are very popular in fever screening. However, the performance of the handheld thermometer depends on the operator and the distance to the forehead. In order to overcome these problems, use infrared proximity sensors to measure the distance between the sensors and the forehead, when the distance is sufficient, the temperature reading will be induced and displayed. In this way, the accuracy of the measurement is improved.
You can set the detection distance of the sensor to the object by adjusting the potentiometer on the sensor module. Clock-time rotating potentiometer will increase the detection distance, and the counterclockwise rotate will reduce the detection distance. I have set this distance to approximately 50 mm.
The connection should be as follows:
ARDUINO -. 1882. Infrared sensor
3.3V ---. 1882. VCC
Land -. 1882.
D9 ----. 1882. OUT
Step 7: OLED display
The body temperature shows the 0.96 "OLED display, the resolution is 128x64, using the I2C bus and Arduino communication. The two pin SCL (A5) in arduino nanno, SDA (A4) is used to communicate.
I am using the adafrouit_ssd1306 library to display the parameters.
First, you must download adafrouit_ssd1306. Then install it.
The connection should be as follows:
Arduino -. 1882. OLED
5V ---. 1882. VCC
Land -. 1882.
A4 ----. 1882. SDA
A5 ----. 1882. SCL
Step 8: LED instructions
Two LEDs are used to indicate that the body temperature is normal or abnormal. Green LED indicates that the body temperature is normal, the red LED indicates an abnormal situation (when the temperature is higher than 104 fairness)
Green LED (LED1) is connected to the Arduino number pin D3, red LED (LED2) is connected to D5. In order to limit the current of the LED, two 330 Ω resistors are used. Welding the resistance to the positive terminal of the LED. Led longer foot indicates the positive terminal.
As shown in the figure above, 4 jumpers are connected to the LED. Here I must use a mother-female jumper to facilitate connection.
Step 9: Alert buzzer
In order to provide an alert during the human screening, a piezoelectric buzzer is used. The buzzer has two terminals, the longer end is the positive electrode, the shorter pin is a negative electrode. The stickers on the new buzzer also have "+" tags, indicating the positive terminal.
You can weld the wires to the buzzer pin, or you can use the mother jumpers I use here.
The connection should be as follows:
Arduino -. 1882. Buzzer
D7 -. 1882. Positive
GND -. 1882. Negative pole
Step 10: Prepare the expansion board
Most modules and components are connected to Arduino Pins 5V and GND. Unfortunately, Arduino Nano has only one 5V pin and two GND pins, but in fact, we need more such pins to connect components. In order to overcome this challenge, I prepared an expansion board using a small prototype board.
In addition to 5V and GND pins, we need two SDA and SCL pins to connect to the MLX 90614 sensor and OLED display.
Here, I use a right angle and straight ahead. You can make it easy to make it on the image. In each row, all pins are short.
Step 11: Production circuit
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The circuit is made according to the schematic diagram given in the above figure. I have explained the connection details of each component and module. For the sake of simplicity, I have prepared a bread circuit for you.
Step 12: PCB Design
After completing the circuit, I found that the wiring is really chaotic. In order to make the wiring cleaner, it is easier, I design a custom PCB for this project. You can freely use my PCB Gerber file.
(The content is transferred from foreign translation, such as intrusion)
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