Is Fiber Optics the Future of Industrial Sensing?
Ian Wright posted on December 05, 2017 | 1563 views
(Image courtesy of AOMS Technologies.)
Sensor technology has come a long way in the last two decades. Manufacturing in the 21st century is all about big data and predictive maintenance, with many factories generating more information than they know what to do with. In the end, it all comes down to sensors or—from a broader perspective—the Industrial Internet of Things (IIoT). had the opportunity to discuss this trend toward increasing instrumentation with Hamid Alemohammad, CEO of AOMS Technologies, a company that’s developed a unique fiber optic sensor technology specifically designed for use in harsh environments.

Can you give us an overview of AOMS’ fiber optic sensing system?

AOMS fiber optic sensor technology is a fully integrated platform which includes sensors, data acquisition hardware, and software. Our technology is a new type of fiber optic sensor that enables sensing of different parameters for environmental, mechanical, and chemical sensing (such as temperature, humidity, vibration, pH, and so on). It can operate in harsh conditions, such as heavy industries, hazardous environments, hard-to-access locations, and environments exposed to high voltage or radiation. Examples are underground monitoring, electrical asset monitoring, chemical processing plants, power plants, oil and gas production and transmission, and infrastructure monitoring.

Is compatibility with the Industrial Internet of Things (IIoT) something your customers are asking for, or are you anticipating a growing demand for that compatibility?

IIoT is actually a growing demand in the industry, based on our market research: everyone is getting into connected systems and connected machines. We’re seeing very large companies developing their own IIoT platform, like GE, Microsoft and Siemens. We designed our system to be compatible with all of them—and we have all the APIs to make those connections—but if a customer doesn’t want to get into the IIoT, they can still use our software and connect it to their own database.

How does a fiber optic sensor system compare with an electronic one?

Electronic sensors and transducers are classified as either passive or active. While active sensors require an external source of excitation, passive sensors transform physical energy to electricity. Both types of sensors rely on the transmission of electrical signals along wires, which could create a lot of problems.  One issue is that you always need to make sure that the quality of the signal from the sensor is good. For example, if you wanted to set up in an environment exposed to electromagnetic fields, your electrical cable could act as an antenna and collect all the environmental noise into the signal. That means you need to do signal cleaning and filtering, and you’re limited in how much you can do. Another issue is multiplexing, which requires sophisticated cable management.

(Image courtesy of AOMS Technologies.)
Our fiber optic sensor is a passive sensor, meaning it doesn’t need an excitation signal to work. Instead, the fiber responds to the environment and modulates the input light wave , then we analyze the light that is reflected and we can tell the temperature or mechanical strain in a specific location. Fiber has a very high capacity for transmitting light waves. As a result, multiple sensors of different types can be consolidated on a single cable of fiber without the need to add extra cables. You can consolidate for example 200 temperature sensors on a single cable which is less than a quarter of an inch in diameter.

Another advantage of fiber optic sensing is for long distance measurements such as hundreds of meters without being worried about the deterioration of optical signals over long distances and losing the signal-to-noise ratio, which is not feasible with electronic sensors unless you have proper cable shielding and signal boosting. In a fiber optic sensing system, although you need electricity to run the laser that generates the light and photo detectors that measure the light, everything after that is purely optical, which is isolated from electromagnetic noise.

Can you tell us about the encapsulation process for the fibers?

Most fiber optic sensors are sensitive to temperature, acoustics, and mechanical strain. The encapsulation of fibers in opto-mechanical metallic and non-metallic packages is our IP. That encapsulation helps us do a lot of other measurements. For other types of sensors, such as pressure, the fiber has to be encapsulated in a transducer to transform the measured parameter, in this case pressure, to mechanical strain on the fiber which will allow you to measure it. If we want a temperature sensor with high sensitivity, the fiber can be embedded in a metal structure with higher thermal expansion.

In addition to metallic structures, we develop transducers with proprietary polymers to convert chemical reactions to fiber optic signals. Examples are hydrocarbon sensing and pH measurement. As you may note, hydrocarbon leakage is a big global problem and direct monitoring of hydrocarbon leakage over large areas is still a problem to solve.

(Image courtesy of AOMS Technologies.)
Other than direct measurement of parameters, AOMS fiber optic sensors can be used for indirect condition monitoring or detection of failure incidents by using sensor measurement as a secondary effect combined with advanced data analytics. Examples are monitoring of corrosion in pipes and vessels. We have developed a special non-invasive fiber optic sensor for monitoring and detection of corrosion which will replace manual inspection which is expensive, unsafe, and inaccurate.

You company was spun out from the University of Waterloo, correct?

Yes, the founders of the company were University of Waterloo graduates. Although we aren’t actually affiliated with the school anymore, we still support R&D there and part of our R&D is still done at the University of Waterloo.

We started developing sensors for the environmental remediation industry as our first point of entry into harsh environment sensing. One of the requirements for remediation is that you remove contamination from the soil or ground water using a process called in situ thermal remediation, where you basically mobilize the contaminants and vaporize them. That requires accurate temperature monitoring, not just at a single point, but cumulative monitoring of the temperature over the whole project. The environmental industry had a lot of issues in terms of monitoring, especially with sensors.

You’ve mentioned a number of different sensor modalities. Are they similar in terms of getting them to work with the fiber optics, or are some types more difficult to integrate than others?

The platform and core technology use fiber optics, so that doesn’t change. What does change is the sensor side, and, of course, the software and analytics are different for different sensors. Chemical sensors, like the ones for pH and hydrocarbons, are the most challenging. You need sensors that are repeatable and reliable. You don’t want something that gives you a false positive because, for example, with leak detection you need a high level of certainty. Otherwise, it’s very expensive to have a false signal.

For more sensor news, check out 4 Innovative Uses of Force/Torque Sensing that Broaden Cobot Applications.

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