You’ve probably walked up to a shop or a library and watched the doors slide open as if they were expecting you. It feels like magic, but it’s actually science and engineering working together. Automatic doors don’t “see” you the way humans do – they sense your presence.Most modern automatic doors use motion sensors. These are usually placed above or beside the doorway. The sensor sends out invisible waves, such as infrared light or microwaves, into the surrounding space. When there’s no movement, the waves bounce back in a steady pattern. But as soon as something moves – like you walking towards the entrance – the reflected waves change. The sensor detects this difference and sends a quick signal to the door’s control system, which activates an electric motor. The motor then slides or swings the door open, often in less than a second.Some doors work differently, using pressure sensors hidden in the floor. When you step onto a special mat, your weight triggers the sensor, and the door opens. In places that need higher security or more precise control, radar or thermal sensors are used. These can even detect body heat, allowing doors to react only to people, not to random objects.Automatic doors make everyday life easier, especially for people carrying bags, pushing prams, or using wheelchairs. They also help with energy efficiency by staying closed when no one is nearby, keeping air-conditioning or heating inside.So the next time a door opens “just for you,” remember – it’s not magic, but a well-designed system of sensors, signals, and motors, all working silently to make your day a little smoother..First automatic doors were invented in 1954Engineer Dee Horton and inventor Lew Hewitt created the first sliding automatic door in America, designed to work with a simple motion sensor..NASA helped improve the sensorsTechnology used in space exploration, like microwave motion detection, inspired more accurate and reliable door sensors back on Earth.
