What Is an Ultrasonic Sensor? How Ultrasonic Sensors Work and Their Pros & Cons

Summary:Ultrasonic sensors measure distance to objects using ultrasonic pulses. They use transducers to send and receive ultrasonic pulses; the reflected pulses carry proximity information. In some applications ultrasonic sensors outperform infrared because they are less affected by dust or dark surfaces.

What is an ultrasonic sensor?

An ultrasonic sensor measures object distance using ultrasound. Ultrasonic sensors transmit and receive pulses via transducers; reflections indicate object proximity.

How do ultrasonic sensors work?

As shown, the sensor emits an ultrasonic pulse. When the pulse hits the target it is reflected back; the sensor measures the round-trip time and computes distance between sensor and object.

Why choose ultrasonic sensors?

Strong environmental robustness: they operate reliably in various lighting conditions, indoors or outdoors, and are less affected by light, smoke, dust, color or material—so in some cases ultrasonic sensors are preferred over infrared.

Wide applications: water level monitoring, UAV obstacle avoidance, distance measurement, etc.

Versatile functions: presence/absence detection, level sensing, position and distance measurement—most non-contact detection needs can be met.

Ultrasonic sensor advantages:

Unaffected by object color or transparency

Ultrasonic sensors reflect sound off objects, so color or transparency does not affect readings.

Usable in darkness

Dark environments do not impact ultrasonic detection, unlike optical proximity sensors.

Less affected by dust, dirt or high humidity

Although they work well in such environments, extreme conditions with heavy dust or water accumulation can still cause incorrect readings.

High precision in some applications

They can provide high accuracy when measuring thickness or distance to parallel surfaces.

Penetration capability

High sensitivity and penetration make it easier to detect certain external objects.

Ultrasonic sensor disadvantages:

Cannot operate in vacuum

Because ultrasonic sensors use sound, they cannot function in a vacuum where there is no medium for sound propagation.

Not suitable for underwater use

Our sensors are not tested for underwater use and doing so may void the warranty.

Accuracy affected by soft materials

Very soft fabrics can absorb sound, making detection difficult.

Small targets may not reflect sufficient sound

Objects may be too small to return enough echo for detection.

Some shapes make echoes difficult to capture

Certain object shapes or orientations can deflect echoes away from the sensor.

These considerations are important when choosing an ultrasonic sensor.

Differences between ultrasonic sensors and reflective photoelectric sensors

Common ultrasonic sensor applications:

Distance measurement

Liquid level detection in enclosed containers

Obstacle detection

Transparent object detection

Automotive collision avoidance

Medical imaging and more