Fluid Level Monitoring Sensor

Technology Summary

Sandia National Laboratories has developed a continuous fluid level fluorescent monitoring 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 magentic coupling, which can pose problems for mobility and hazardous fluids.


The fiber optic technology of this Sandia invention uses a single waveguide, that can be produced from a non-corrosive polymer material and a total internal reflection method to provide accurate and continuous measurements of fluid levels in a sealed container.  The present Sandia invention can also measure the interface between two immiscible fluids of different refractive index.  A comprehensive explanation of this technology has been published in Optical Engineering (August, 2000).


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

Applications and Industries

  • Liquid Pumps and Dispensers
  • Oil, Water, and Gas Tanks on Vehicles, Aircrafts, and Remote Devices
  • Food Processing and Storage
  • Water Waste and Treatment

Intellectual Property

ID Number
Patent Number
Fluorescent optical liquid level sensor 5911.0 6,172,377 01/09/2001
Technology IDSD#5911Development StagePrototype - Sandia estimates this technology at approximately TRL 5. Key elements 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.Published09/29/2011Last Updated02/06/2013