Skin Temperature Scanner

Abstract

This project aims to estimate the human body temperature with a thermal camera connected to a Raspberry Pi computer. Packaged with a battery and small screen, you can create a portable, handheld device to have a quick measure if someone has fever or not.

animation	device

Part list

For this prototype, the following hardware has been used:

Raspberry Pi 2, 3 or 4
MLX90640 Thermal Sensor, 32x24 px
Waveshare 4.3inch HDMI LCD (B), 800x480, IPS
5V 2.4A power adapter (2x)
microSD card 8Gb or larger

MLX90640 Far infrared Thermal Sensor

The MLX90640 is a thermal camera made by Melexis N.V. It has a I2C interface, which is perfect for the Raspberry Pi and other embedded devices. You can find the C++ API, driver and documentation on their Github page. The company Pimoroni has made a breakout board around this sensor, for easy integration with a Raspberry Pi.

Research

Setting	Value	Reference
Emisitivity of human skin	0.99	[1]
Average human skin temperature	32-34 degrees Celsius	[2]

Deploy on Raspbian

Setup the Raspberry Pi

The software is made and tested on Raspbian (Buster). Open /boot/config.txt and make the following changes:

## Display settings
max_usb_current=1
hdmi_group=2
hdmi_mode=87
hdmi_cvt 800 480 60 6 0 0 0 
# Rotate the screen to portrait mode
display_rotate=3

## Settings for the thermal sensor
dtparam=i2c_arm=on
dtparam=spi=on
# Add support for FPS > 16
dtparam=i2c1_baudrate=1000000

If you don't want to make these settings by hand, you can also copy the resources/boot/config.txt from this project:

cp ./resources/boot/config.txt /boot/config.txt

Reboot the computer after changing the config.txt file.

Dependencies

In the bin directory is a script, called install_dependencies.sh.

Download the precompiled binary and run the app

Download the latest release and unpack the application in your preferred location:

tar zxvf ThermalCamera_1.0.1_raspbian_buster_armv7l.tar.gz
cd ThermalCamera/bin
./install_dependencies.sh

Check the settings in /boot/config.txt like described above. There is an example file in resources/boot/config.txt in this bundle. After changing the config.txt file, reboot the Raspberry Pi.

To run the application:

cd ThermalCamera/bin
./ThermalCamera

Build from source

Instead of downloading the precompiled binary, you can download the source files and compile it yourself by following the steps below:

git clone https://github.com/gilbertfrancois/skin-temperature-scanner.git
cd skin-temperature-scanner
./bin/install_dependencies.sh
mkdir build
cd build
cmake ..
make
./ThermalCamera