DFRobot mmWave - C4001 24GHz Human Presence Detection Sensor - 25m

This sensor serves as a replacement for a PIR sensor and works on the basis of millimeter waves and the doppler effect. Due to a difference in speed, this sensor can detect motion, this also works through almost all materials except metal. The sensor status can be read via the "OUT" pin. In addition, you can use the UART interface to read out more information such as detection distance, and adjust measuring settings.

See the following page for more information: Wiki