Fibre Optic Based Cryogenic Monitoring System


Electronics - Sensors & Instrumentation
Energy - Sensor, Network, Power Conversion, Power Quality & Energy Management


To facilitate a safety monitoring system for temperature variation of cryogenic medium, including liquefied natural gas (LNG) and liquid nitrogen (N2), etc., a fibre optic based cryogenic safety monitoring system was developed. The invention consists of fibre optic based cryogenic sensors, a full functional fibre optic data logger, as well as a software package for data analysis, data virtualization and remote transmission.

The main purpose of this technology is to increase the accuracy of fibre optic based sensors for the temperature measurement in the cryogenic environment. When being utilised in low temperature environment (-165 degC), the sensitivity of conventional fibre optic sensors may be dramatically reduced, which makes the temperature measurement uncertainty more than ±2 degC. Conversely, the technology utilises PI-coated fibre optic components and special designed substrates to increase the sensitivity of fibre optic sensors in the cryogenic environment. Consequently, the temperature accuracy of fibre optic sensors can reach ±0.5 degC.

Unlike the electrical based sensors which suffer from potential safety issues, the fibre optic based crygenic monitoring system is intrinsically safe, immune to electromagnetic interference, explosion proof and corrosion resistant. Therefore, the technology can be used to measure and monitor the temperature of cryogenic medium as an alternative of electrical based sensors.

The technology owner is seeking industry partners for technology commercialisation opportunities. 


The main specifications of the fibre optic sensors are:

  1. Temperature measuring range: -195 degC to 30 degC
  2. Accuracy: ±0.5 degC

The main specifications of the loggers are:

  1. Wavelength ranges: 1515-1565nm
  2. Wavelength resolution: 1pm
  3. Scanning frequency: 5kHz

The developed FBG sensors utilise host materials with higher coefficient of thermal expansion (CTE) to enable thermal expansion of the sensors at high temperature and bring extra wavelength shift which is more durable, easier for networking and intrinsically-safe. 


The technology can be used to monitor the temperature of cryogenic medium. It provides an alternative of the electrical based sensors for the cryogenics related industries. LNG industry can use this technology for safety monitoring of LNG terminals, LNG tanks and LNG carriers.

Other cryogenics related industries can also use this technology to measure the temperature of liquid nitrogen, liquid hydrogen and liquid oxygen. The products that can be marketed based on this technology are fibre optic cryogenic sensors, data-loggers for fibre optic and software. These products formed an integrated cryogenic temperature measurement system.


For the cryogenic monitoring, the electrical based sensors and data-loggers are widely utilised. However, when being utilised in cryogenic medium with the potential of high flammability and prone to explosion, such as LNG, liquid hydrogen and liquid oxygen, the electrical based sensors may suffer from potential safety issues. Unlike the electrical based sensors, the fibre optic based cryogenic monitoring system is intrinsically safe, immune to electromagnetic interference, explosion proof, and corrosion resistant.

The state-of-the-art fibre optic sensors related products cannot measure cryogenic temperature (-165℃) with an accuracy of ±0.5℃. The developed technology improved the temperature accuracy in the cryogenic enjoinment and tackled the challenges of accurately measuring the temperature of cryogenic medium. 

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