Learn how to implement a touch-free input using an Ultrasonic Range Sensor HC-SR04 with Arduino or ESP32 in this 20-minute tutorial video. Explore an alternative to traditional button inputs, ideal for creating Covid-secure interfaces in escape rooms or public-facing Arduino projects. Follow along as the video demonstrates the sensor's functionality, guides you through hardware wiring, and provides a detailed Arduino code listing. Gain insights into this cost-effective and easily accessible module, perfect for microprocessor-based projects. By the end of the tutorial, you'll have the knowledge to create touch-free interfaces using ultrasonic technology, enhancing the safety and interactivity of your Arduino or ESP32 projects.