FIBER OPTICS SENSING (2012)
FIBER OPTICS SENSING
(2012)
MICROFLUIDICS SYSTEMS
(2021)
STRUCTURAL HEALTH MONITORING.
We have intimate knowledge of optoelectronics systems, including on building custom fiber optics sensing systems. Our field work included the use of these sensors in bridges and high-stress structures. Also, we built custom-made fiber Bragg grating (FBG) interrogators. (W = 2)
Structures need to be monitored. A Fiber Bragg Grating (FBG) sensor does this particularly well because it is very sensitive to external forces. And it is immune to Electromagnetic Interference (EMI). In the picture, a shift in the peak of the profile means it detects a strain, and if the shift is big enough, a warning sign.
One of the challenges though, was to read the FBG. It required a small lab. And commercial systems were VERY costly. Enter the story on FBG interrogation. But how does it work?
ENTER TEXT ON A TOUCHSCREEN, AND A SWITCH BEEPS!
In a maze of various switches and servers, it can be quite daunting to find it even with proper documentation of the layout. If an asset of concern (say, a switch or router) needed finding, one could just enter the text of the serial number of the asset, click a button, and the device attached to it would beep. (W = 2)
Imagine being in a huge room full of cheap furniture, and you need that fragile rack. It can be quite daunting to find the right one. So one does it old school: they just squint and "ooh" and "aah" until they find the right unit.
Telco companies have similar problems with their switches or routers. And when one of them needs to be inspected or replaced, it can take a long time to find the right one.
So the idea is: they wanted an screen to key in the serial number, and the right equipment will light up and buzz and make a helluva noise so we can find it.
Original photo by Silas Baisch
Source: unsplash
This is how it looks like (image below) if a fiber sensor is being "interrogated". A tunable laser sweeps through different bandwidths to profile the sensor.
The sensor output is read with a photodiode, converted via Analog-to-Digital circuitry and the output can map the sensor profile. Let's have a look at how the smaller device was developed.
The Interrogator (playfully called BraggScann) was built mainly from computer parts, Frankensteined with the more costly optical parts. We published paper about it much later, with a patent.
If you must know, it was built with a 980nm butterfly laser, pumping an Erbium-doped Fiber with a tunable bandpass filter in it, driven using electromechanical means, using the single-mode EDFA ring laser configuration. The output from the sensor was read using a fiber-based InGaAs photodiode, fed to a 15-bit ADC (ADS1100). All were spliced and assembled within the enclosure. The microcontroller was a PIC18F4455. A gone era where PICs dominated the scene.
Our FBG sensor was installed in one of the segments of an arch spandrel bridge in Melaka. This picture (image below), among many, showed us looking at the sensor after it was installed. And, well, here's some news coverage on it (image below).
Forgive the sentimentality, but the state of Melaka makes us remember that there are also other things in life which is very important. Like a good asam pedas fish.
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*Note: To aid the viewer's perspective, we added weightage W, followed by a number, which states the estimated number of sub-projects within it.
Usually, one project has several major facets which need to be dealt with separately from the others before they converge as a single. A medical device generally has the most facets due to the multidisciplinary aspects, including embedded programming, electronics, optical alignment, prototyping design and aesthetics, and also interface programming, hence, W = 6.
This highlights that the entries presented are all significant, though not equally so, and that each is distinct.
