Affordable Intelligent Contactless IR thermometer

Details

Science the beginning of COVID-19 pandemic, the world order is seem changed. ?The first impact is shortage of global supply chain especially in medical supply. All of daily used and simple, penny medical supply are out of stock. The basic need such as mask, thermometer and high tech ICU gear such as ventilator are out of supply.

I live in Myanmar. Yes, a green country recently opened it's door. Even from associations such as WHO and international health advisory focused at first it is not easy for country like Myanmar. Everybody said Myanmar may not control outbreak and first wave. Surprisingly, ?they are wrong. Myanmar government, Ministry of Health and Sports, groups of local volunteers and non-profit origination, the help of the kind and generous people around the country?, Myanmar can handle successful the first wave.

At the beginning, there are thermal screening check points in public terminal, airport, highway buses etc. After the first wave, the Government carefully released lockdown step by step. High school, offices, factory and some public area are allowed to open under stricted guide lines. There are high demand of non-contact thermometer and thermal imaging camera. But due to global lockdown, the supply for these devices are shortage and delivery is also facing delay and uncertain.

That is the background what we are facing now.

There are two types of thermometers which used for thermal screening, handheld gun type and thermal scanner. They both have drawbacks.

Handheld type are cheap and easy to use
- But they are not accurate depends on type of brand and correct usage
- Even cheap china unknown brand are now selling with high price tag due to demand
- There are fake thermometer !!! display always 36 or 37 degree C , DAM
- Because of low quality construction, they are not durable for long use (imagine checking hundred of students morning and evening in a High school)
- REQUIRED AN OPERATOR who may affect because of close distance
Thermal Imaging Camera are good in both accuracy, quality, social distancing and durability
- BUT, THESE DEVICES ARE EXPENSIVE especially for country like mine :(

My idea is to design and construct a prototype for these advantages of two models

The cost must be AFFORDABLE , (between handheld type and thermal imaging camera)
Must be automatic measurement and alert
Simple to construct for DIYer
Parts must be commonly used and can be sourced easily

Hope this will useful for My country and people around the world. Be safe from Covid. Lets start the project

Components

1 × ESP32 DEV Module

1 × MLX90614 Infrared Thermometer Electronic Components / Misc. Electronic Components

1 × IR Infrared Obstacle Avoidance 3 Wire Reflective Photoelectric Sensor Module

3 × MAX7219 4 Digit Seven Segment Display Module Interface and IO ICs / Display Interface

3 × LED 2.5mm Red, Green, Yellow each

Project Logs

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V1.2 Dotmatrix Display
oakkar7 • 09/04/2020 at 05:13 • 0 comments
Original idea is to use big 7-Segments display for better visibility and price. After revising design, I decide to use 8x8 dotmatrix display with driver MAX7219. These module are cheap and also good for displaying symbols, character.

So, revised design V1.2 is as follow.

MAX7219 modules can be cascaded easily to expand digits. There are a lot of Arduino driver to interface this module. I selected the following Lib science many functions and modules are supported.

Lib:

https://github.com/MajicDesigns/MD_MAX72XX

MAX7219 Connection:
- Vcc - ESP32 3.3V
- GND - GND
- DATA - ESP32 23
- CLK - ESP32 18
- CS - ESP32 15
LED:
- NORMAL LED - ESP32 25
- WARNING LED - ESP32 26
- ALERT LED - ESP32 27
- BUZZER 14 - ESP32 14
Schematic :

Added LED and buzzer functions.

When I moved my finger near ir+distance sensor, the result is like that. Symbol C is not displayed full digit. Required additional display or tweak fonts?

V1.2 Code was added to my github, though I need to clean and touch code more.

https://github.com/oakkar7/AVCTV1
Adding 7-SEG Display
oakkar7 • 08/31/2020 at 15:46 • 0 comments

The first idea was to use MAX1719 display driver. But due to late delivery of my parts order, I have tested with inhand TM1637 4 Digits 7 segment display driver module. Quick google search and after test, temperature is shown successfully in Deg C.
Lib use: https://github.com/avishorp/TM1637
Connection:
Vcc - 3.3V
GND - GNE
CLK - ESP32 18
DATA - ESP32 19
# Note : Need to find out a way to enable single dot for decimal point. (or) MAX1719 with 8x8 dot matrix display?
Testing Automatic Reading with IR sensor
oakkar7 • 08/31/2020 at 14:40 • 0 comments

The idea of design V1 is automatic measurement when object is closed to sensor. MLX90614 sensor reading distance is 2~5mm. So, IR reflected sensor TCRT5000 is used to measure proximity distance. Circuit is simple. Analog out is connected to ESP32 pin 34 (ADC input).
Changed the code snip a little to measure if threshold ADC reading is changed. When the hand is closed to IR sensor and IR reflected sensor, temperature measurement is performed.
TCRT5000 Connection
Very rough test circuit for now :)
Initial Testing
oakkar7 • 08/31/2020 at 14:04 • 0 comments

The first step is to test MLX90614 sensor with ESP32 dev (Node MCU) board. Test is straignt forward. By using Adafruit Adafruit-MLX90614-Library, sensor was simply tested by UART output.
Lib Link: https://github.com/adafruit/Adafruit-MLX90614-Library
Connection :
VIN -> ESP32 3.3v
GND -> ESP32 GND
SCL -> ESP32 22
SDA -> ESP32 21
V.1 Design
oakkar7 • 08/30/2020 at 07:30 • 0 comments
My first idea is to use Infrared Thermal array sensor like MLX90640 with powerful MCU. But my DHL order is stuck and on hold on the way. Meanwhile waiting the main parts, I like to start the project V.1 with inhand parts.
The system design of V.1 is simple.
- Use ESP32 (may extend the Camera support later)
- MLX90614, single dot contactless IR thermal sensor which widely used by many arduino and DIY project
- Infrared distance sensor (pair of IR LED and Photo Diode) to measure target body distance under test
- 7-Segments LED display with MAX7219 driver (Rather than LCD or OLED, it is cheap, clearly visible under day light and durable)
- R, G and B Led , to alert normal, warning and critical temperature condition
- A buzzer to beep alert sound
- Used as wall mount or with a tripod stand
Working Principals
When a target under test is closed to measurement range, ( measured with IR reflection sensor) temperature is measured and displays automatically
If temperature is normal, Green LED will light on with a buzzer single beep, if not Warning Yellow or Red LED will be flashed depends on temperature and buzzer will beep noticeable tone.
Fig 2. Version-1 System Design