Detection of Clear Liquids in Transparent Packaging

I.V. Bag Liquid Detection Image

Application: Detecting clear liquid in clear IV bags

Challenges: Sensing water based-liquids

Solution: The QS30H2O series sensor

Benefits: Uses a specific wavelength that is attenuated by water

Detecting clear liquids—like saline solutions and liquid vaccines and mediations—inside clear IV bags, glass vials, and plastic syringes is a common sensing application in pharmaceutical packaging. The lack of contrast between the presence of a clear liquid and its absence makes detection challenging, especially when using a standard photoelectric sensor operating in the visible red wavelength from 620 to 685 nm. Light does not attenuate in water well in this range. A sensor that operates in the mid-infrared range is needed for accurate water-based liquid detection.


Banner’s QS30H2O was developed specifically to address challenges with optically sensing the presence of water and water based-liquids. The QS30H2O operates in a through beam sensing mode and the emitter has a unique LED with a 1450 nm wavelength in the mid-IR (infrared) range—a wavelength that is easily attenuated by water. 

By using the 1450 nm wavelength LED, the QS30H2O can effectively and accurately detect water. When water is present, the wavelength is weakened, and the sensor does not detect a significant amount of light. When water is not present, the sensor detects a high amount of 1450 nm light and sends a signal to a PLC to alert operators of the water’s absence. 

The QS30H20 detects clear liquids in clear containers in a different wavelength compared to standard photoelectric sensors for improved contrast in these types of applications. The high excess gain of the sensor makes it powerful enough to pass through some plastic and glass containers, while still maintaining its sensitivity to water inside the container.

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