Researchers from the Indian Institute of Science have developed an accurate pressure sensor that can be operated remotely from kilometres away. Built using optical fibres, this sensor can detect minute variations in pressure and operates at high speeds. Unlike conventional pressure gauges, this sensor is not affected by electromagnetic interference.
An optical fibre is a flexible, transparent wire like structure made of glass that is slightly thicker than human hair. It can be drawn kilometres long and transmits light from one end to the other. The optical fibre is widely used in communication systems such as telephone cables among others due to its ability to transmit information at very high speeds with minimal loss. The use of these fibres is so wide-spread that all the continents except Antarctica is connected by optical fibre under the sea for internet, telephony and private data transfer!
Harnessing the optical properties of these fibres, a new class of sensors called “Fiber Bragg Grating (FBG)” sensors are developed. The FBG sensors reflect particular wavelength of light and transmits all others. Fibre Bragg Grating based sensors are commercially used in health monitoring of buildings, bridges and aircrafts to accurately measure pressure, temperature, humidity, chemical, flow and for level sensing.
Precise measurement of pressure in pipes and channels are critical in oil, gas and chemical industries. Since the sensors often have to be mounted in inaccessible locations which require remote operation, we need to think beyond the conventional pressure gauges. Addressing this issue, the research group at IISc comprising of Shikha and Sharath under the guidance of Prof S Asokan, have developed a Fibre Bragg Grating based pressure sensor which can accurately determine the pressure inside a pipeline carrying a fluid, gas or chemical.
"In an industrial environment, real time pressure monitoring becomes crucial. This methodology employs the hoop strain on the walls of a column (expansion at the outer surface of the pipeline) as an indicator of the pressure inside the column", says Prof Asokan.
The new methodology can measure changes in pressure even if it is mounted on the outer surface of the pipeline. Depending on the pressure inside the pipeline, the surface of the pipe expands or contracts and the sensor is sensitive enough to sense these minute changes. Since the sensor sits outside the pipe, it can be used in corrosive environments too.
"Placing conventional pressure sensors inside pipes or columns have many drawbacks, the most important one being its exposure to the gas or fluid inside", adds Prof Asokan explaining the novelty of this approach.
Since the communication of data is through a fibre, the data acquisition system can be placed kilometres away from the sensing equipment, thus enabling remote sensing with minimal loss. “The proposed sensors are non-invasive and provide real-time dynamic monitoring of pressure”, signs off Prof Asokan.
About the authors:
S. Asokan is a Professor at the Department of Instrumentation and Applied Physics and Chairman, Robert Bosch Centre for Cyber Physical Systems, Indian Institute of Science, Bangalore, India. Shikha and Sharath are PhD students in the Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, India.
Prof. S. Asokan can be contacted at +91(80) 22933195.
Prof Asokan's lab: 22932637
Link to abstract of the publication: