Ultrasonic sensors are devices that convert ultrasonic signals into other energy signals (usually electrical signals) to measure distance from the sensor to the target object. The ultrasonic wave is a mechanical wave with a vibration frequency higher than 20KHz and it has the characteristics of high frequency, short wavelength, small diffraction phenomenon, especially good directivity, which can become rays and propagate directionally.
The ultrasonic sensor can be used as an ultrasonic distance sensor to measure the distance of a target object, detect the presence of as well as the movement of the object by applying the electrical signals to the 40khz ceramic transducer (transmitter) to transmit ultrasonic waves and convert the reflected sound into electrical signals. Read more about the product here
How do ultrasonic sensors work?