The value of the sensor lies in its ability to accurately and reliably make measurements. Usually used in harsh environments, the reliability and service life of the sensor will be shortened due to external conditions. The measurement accuracy depends on where the sensor is placed.

Generally, due to the risk of damage, the precision sensor cannot be correctly placed at the required measurement position, resulting in inaccurate readings.

NASA is aware of these issues surrounding measurement technology. Therefore, its engineers set out to improve the way they monitor their systems, especially low-temperature fuel lines.

Fabrisonic and Luna developed SensePipe through NASA's Small Business Innovation Research (SBIR) program. The sensor can measure the pressure and temperature of cryogenic fluids. It is strong, low-key and does not hinder flow.

The sensor will improve fuel line monitoring to improve the efficiency and safety of rocket engine testing and launch.

Luna Innovations is a fiber optic company based in Virginia, specializing in point and distributed fiber optic sensors.

Fabrisonic is an additive manufacturing company in Ohio dedicated to advancing a proprietary process called Ultrasonic Additive Manufacturing (UAM). UAM is a solid state process, which means that almost no heat is generated during the metal bonding process.

The solid-state nature of Fabrisonic's UAM enables Luna to fully embed sophisticated fiber optic sensors in metal parts without damaging the sensor.

SensePipe is a thick-walled stainless steel pipe section that contains two embedded fiber optic sensors that can continuously monitor changes in local pressure, stress, strain, temperature, and heat flux.

The sensor is intended to be installed in NASA's existing gas pipeline on the rocket engine test bed.

Construction began when Fabrisonic used UAM technology to embed two optical fibers into the pipe wall. The final pipeline structure will expand and contract according to the fluid or environmental conditions.

These two fibers will then respond proportionally to these changes to determine the parameters of pressure, temperature, and heat flux. This flexibility of implementation allows for different configurations according to customer needs.

As part of SBIR's work, early SensePipe prototypes were made of aluminum and tested at temperatures from -191°C to 70°C (-313°F to 158°F) and pressures up to 20.6 MPa (3,000 psi) .

The prototype SensePipes can demonstrate pressure and temperature accuracy better than 3% and 7%, respectively.

The second generation (GenII) SensePipes are recently made of stainless steel 304 (SS304) and are designed to withstand extreme low temperatures (-253°C) and pressures up to 41.4 MPa (6,000 psi). GenII SensePipe is designed to measure pressure and temperature with 0.25% accuracy. It is expected that testing and demonstrations will begin in the next few months.

By embedding fiber optic sensors, Luna Innovations and Fabrisonic are promoting the development of new and improved structural health monitoring and data collection methods in extreme environments. SensePipe is the result of collaborative technology, which aims to create new solutions for complex and challenging industrial challenges.