One of the most prevalent 'weapons' against COVID-19 has been the use of non-contact IR thermometers for people to measure the temperature of individuals. Back in April we looked at making such device but realized quickly that there were no IR sensors available - they had been hoovered up by manufacturers to meet demand. Last month they finally arrived and we quickly printed off a design to demonstrate that yes, this 3D PCB Printer can be used to make your own touchless anti-COVID solution!
At the heart of the thermometor is an ATMEGA328-P chip which uses I2C pheripherals such as an OLED display and an MLX90614 infrared thermometer sensor to measure IR radiation from an object. Stored on the IC is a table that turns analog data from the IR sensor into approximate temperature values which is displayed on an OLED display at the top of the device.
This device was designed in a single layer, and made to use a 20-pin edge connector. All the components on the device, including the ATMEGA328-P, the MLX90614, and the SSD1306 OLED display all operate at 3.3V supplied by the AZ1117-3.3 Linear Voltage regulator. The power source for the voltage regulator is an on-device AAA battery pack, making the whole device portable with a lengthy 36 hour charge.
Operation is simple: flip the switch to turn it on and then press the red trigger on the handle. This should cause the thermometer to emit a laser beam to help the user target and then show the measured temperature on the OLED display located at the top of the device.
Designing and printing the plastic body was trivial and accomplished on a Makerbot Replicator 2x while the SV2 was printing the circuit. We soldered the board using our new pastes (read about it here!) on the machine using the heatbed for reflow. End to end, the design, programming, manufacturing and assembly took less than a day.