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Fluid Interface Position Optical Sensor


Sandia National Laboratories has developed a continuously monitoring fluid interface optical sensor.  The method of determining the liquid level through a single immersed optical wave guide allows for a simple and mobile solution to fluid monitoring systems.  Current technologies use monitored floating devices and require mechanical or magnetic coupling, which can pose problems for mobility and hazardous fluids.  Current technologies employ a non-contact method for sensing transparency of liquid which lack the precision and safety of a single optical waveguide method.


The fiber optic technology of this Sandia inventions utilizes the principle of dual-fluorescence, where a primary and secondary fiber are used to compare emitted to absorbed light in the system and calculate the position of the interface between opaque and clear fluids.


  • Mobile and simplistic
  • No moving parts
  • Continuous monitoring
  • Safe for use with flammable or hazardous liquid
  • Can operate over a wide range of wavelengths
  • Response wave shape can be adjusted to provide more controlled measurements

Applications and Industries

  • Measurements of hazardous materials or contaminations
  • Crude oil levels
  • Biofuels
  • Wastewater treatment

Intellectual Property

ID Number
Patent Number
Optical position sensor for determining the interface between a clear and an opaque fluid 7466.1 7,049,622 05/23/2006
Technology IDUS Patent# 7,049,622Development StagePrototype - Sandia estimates this technology at approximately a TRL 5. Key components of this technology have been demonstrated in relevant environments. AvailabilityAvailable - Various licensing and partnering options are available. Please contact the Intellectual Property department to discuss. Published07/27/2012Last Updated01/23/2013