What is an Ultrasonic Sensor?

An ultrasonic sensor is a device that converts ultrasonic signals into other forms of energy, typically electrical signals. Before we introduce ultrasonic sensors, let's first understand the basics of ultrasonic waves.

Sound waves are mechanical waves that can propagate through gases, liquids, and solids. Based on frequency, sound waves can be categorized into infrasound, sound waves, and ultrasound. Ultrasound usually refers to sound waves with frequencies that exceed the lower frequency and audible range (20 Hz to 20 kHz), which are inaudible to humans.

As ultrasonic waves propagate through a medium, their energy gradually attenuates with increasing propagation distance. The attenuation of energy is determined by the diffusion, scattering, and absorption of ultrasonic waves.

Devices that use ultrasonic waves as a detection method and can generate and receive ultrasonic waves are called ultrasonic sensors. There are various types of ultrasonic sensors with different structures, including straight probes (longitudinal waves), angled probes (transverse waves), surface wave probes (surface waves), Lamb wave probes (Lamb waves), and dual probes (one probe for transmitting and one for receiving).

Industrial Field: Used in material inspection, liquid level detection, displacement measurement, etc.

Automotive Field: Used in parking assistance systems, obstacle detection systems, etc.

 • Measures the liquid level and solid level in closed or open tanks.

 • Manages and monitors water levels in rivers, streams, ponds, and canals.

 • Measures water levels in rivers and bodies of water to warn relevant parties of floods and tsunamis.

 • Manages water usage to protect resources, enhance safety, and improve efficiency.

 • Monitors fuel inventory, tracks its usage, and prevents potential theft.

 • Measures the height of liquid in weirs, channels, and flumes to calculate the volumetric flow of eluents and water.

 • Measures the height and size of objects like containers and boxes.

 • Calculates the diameter of paper, film, or foil rolls to detect variables such as roll tension or remaining material.

 • Measures the free movement of materials as they move from one machine to another to prevent damage.

 • Measures the position of objects in a closed-loop system to maintain or control their position.

 • Detects objects for counting, safety protection, inventory checks, or helps automated moving agents (such as robots) avoid obstacles.

 • Detects people in a scene and determines whether they are approaching or leaving.

 • Can monitor targets across the entire sensor range or restrict it to a user-defined distance range.

 • Long-distance applications may involve detecting the presence or absence of objects and/or materials, as well as avoiding obstacles.

 • Industrial ultrasonic sensors can detect large and small targets, including solids, liquids, and particulate materials.

 • Ultrasonic sensors are not affected by optical characteristics such as color, transparency, reflectivity, or opacity. However, certain variables (including the shape, size, and orientation of the target) will affect the maximum detection range of the ultrasonic sensor.

1. Characteristics of the Measured Object: Flat Objects: Such as liquid surfaces, glass, etc; Cylindrical Objects: Such as cans, bottles, etc; Granular or Blocky Objects: Such as coal, cement, plastic granules, etc.

4. Detection Distance: The maximum detection distance for reflective sensors is 6 meters (e.g., CSB30 series); The maximum detection distance for through-beam sensors is 100mm (e.g., CSDA series).

 • The surface temperature of the target object exceeds 100°C.

 • The wind speed in the detection environment exceeds 60 km/h.

 • The operating environment is at an altitude above 3,000 meters.

 • The pressure in a sealed environment exceeds 1.2 standard atmospheres.

 • The operating environment has temperatures below -20°C or above 70°C.

 • In non-reflector mode, detecting highly sound-absorbing materials such as felt, wool, cotton, or sponge foam.

 • Sound waves cannot propagate in a vacuum. Therefore, ultrasonic sensors will fail in vacuum environments.

 • Detecting other unknown substances or in uncertain usage scenarios.

Sonar sensors are primarily used to directly detect and identify objects in water and the contours of the seabed. A sonar sensor emits a sound wave signal that, when it encounters an object, reflects back to the sensor. The sensor then calculates the distance and position of the object based on the reflection time and waveform. Sonar sensors are typically used for biological detection, such as identifying what types of creatures are present on the seabed and their sizes. The devices you may have heard of for detecting sea monsters are sonar sensors.

Ultrasonic waves have strong penetration capabilities, especially in opaque solids, where they can penetrate to depths of several tens of meters. When ultrasonic waves encounter impurities or interfaces, they produce significant reflections that form echoes; when they encounter moving objects, they generate a Doppler effect. Ultrasonic sensors are developed based on these characteristics of ultrasonic waves.