You can check the working principle of the IR Thermometer here: IR Thermometer Working.

The sensor uses IR rays to measure the temperature of the object without any physical contact. The sensor can be used to measure the temperature of a particular object between -70☌ to 382.2☌. The MLX90614 is a Contactless Infrared (IR) Digital Temperature Sensor from Melexis. MLX90614 Contactless IR Temperature Sensor The component purchase link is given below. All the components can be easily purchased from Amazon. The IoT Based IR Thermometer requires following components. Blynk is an IoT platform that allows you to quickly build interfaces for controlling and monitoring your hardware sensors from your Smartphone. We will connect the ESP8266 to the WiFi Network & send the temperature data, i.e Ambient Temperature & Object Temperature to the Blynk Application Dashboard. Here, we will interface MLX90614 Sensor with NodeMCU ESP8266 & 0.96″ OLED Display. The IR Temperature Sensor MLX90614 from Melexis can be easily connected to any microcontroller using the SMBus Protocol, which is similar to I2C Protocol. Infrared radiation means a type of electromagnetic radiation below the visible spectrum of light. An infrared thermometer is a device that measures the infrared radiation emitted by an object. This DIY Infrared Thermometer is the low-cost contactless Thermometer for measuring body temperature or the temperature of very hot bodies. In this project, we will build our own IoT Based IR Thermometer using MLX90614 & ESP8266 & monitor the temperature on the Blynk Application. Testing IoT Based IR Thermometer on Blynk.Circuit Digram & Connection: MLX90614 + NodeMCU + OLED Display.MLX90614 Contactless IR Temperature Sensor.

Mlx90614 library for proteus