Principle of the Ultrasonic Air Bubble Detector

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In the realms of clinical medicine and biological studies, precise fluid measurement is often required, as seen in blood transfusions, biomicroluidic sample analysis, etc. Bubbles in fluid flows can disrupt their function, particularly in microluidic handling. Bubble formation is influenced by several factors like pump driving, pressure differences in paths, and varying pressures inside and outside the liquid surface, making them challenge to avoid or eliminate. Many techniques are employed to detect microbubbles in tubing, such as capacitive, photoelectric, and ultrasonic detection. Of these, ultrasonic air bubble detector stand out for their directional focus and penetration ability. Easily accessible and highly accurate, they are an excellent choice for bubble detection in tubing.

infusion pump

Figure 1. Infusion Pump

Ultrasonic waves travel straight through uniform media. But, upon encountering interfaces or different media, they undergo reflection and refraction, adhering to laws like geometric optics. Ultrasonic propagation within a medium is accompanied by attenuation, categorized into three types: diffusive, absorptive, and scattering attenuation. Bubbles in tubing mainly cause the latter two. The ultrasonic air bubble detector operates on the principle of ultrasonic transmission medium attenuation. Water and air have characteristic acoustic impedances of 1.5*106 kg/m² and 430 kg/m², respectively. If an ultrasonic wave moves from water to air, the interface sound intensity reflection ratio is 0.999, and transmission ratio is 0.001. This means almost all energy is reflected at the boundary surface when ultrasonics travel from water to air. In the ultrasonic air bubble detector, ultrasonic waves are emitted on one side of the tubing and received on the other. The presence of bubbles in the liquid significantly reduces the ultrasonic energy at the receiver. This change in signal is then fed back, achieving the detection of bubbles in the fluid path.

air bubble detector

Figure 2.Ultrasonic Air Bubble Detector 

Holding nearly 40 years of industry experience, Siansonic Technology stands as a high-tech enterprise in China, specialized in the development, production, and sales of piezoelectric and ultrasonic technology products. Siansonic offers a diverse range of ultrasonic air bubble detectors, including non-contact, industrial, analog, and metal tube types, catering to a broad client base. Additionally, they provide customized services, accommodating various diameters and tubing materials.





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