PolyU Speciality Optical Fibre Laboratory Unlocks Limitless Applications

PolyU Speciality Optical Fibre Laboratory Unlocks Limitless Applications

Optical fibre technology is rapidly evolving, expanding beyond its traditional role in network connectivity to encompass diverse applications, from structural monitoring in engineering construction to seabed monitoring of shipping lanes. This evolution is fuelled by expertise in fabricating optical fibres using diverse materials, enabling the development of specialty fibres with unique capabilities that unlock limitless potential across industries.

Professor Hwa-yaw Tam, Associate Director of the Photonics Research Institute at The Hong Kong Polytechnic University (PolyU), boasts over 20 years of experience in optical fibre sensor research. His dedication to applying optical fibre technology across various fields has brought significant advancements, including enhanced railway maintenance efficiency, as well as innovative medical sensors that pave the way for future robot-assisted surgery.

Predicting Problems in Advance: Enhancing Railway Maintenance Efficiency

The safe functioning of trains relies on rigorous daily inspections by railway companies. Within this regimen, the wheels require routine turning to ensure safety and stability.

"Typically, wheels need to be turned every 18 months to ensure smooth and safe operation," Professor Tam explained. "However, depending on the route and specific conditions, some wheels may only need turning after three years. Turning the wheels prematurely could lead to an unnecessary rise in maintenance expenses and shorten the wheels' lifespan."

To address this issue, the Hong Kong Mass Transit Railway Corporation (MTR) has implemented the optical fibre sensing network developed by Professor Tam’s team. This system includes sensors placed on both the tracks and trains to gather information on variables like temperature, train velocity, and wheel profiles. This system provides round-the-clock monitoring of operational conditions to boost efficiency in train operations.

“By placing just a few sensors at a specific location on the rail track, we can assess the status of every train that passes by, simultaneously, sensors mounted on the trains in operation constantly monitor the condition of the track and train structure.” Professor Tam detailed. This reciprocal verification approach guarantees that both the track and train are in prime condition, allowing for accurate data collection. “Utilising machine learning to analyse the real-time data, we’re also capable of forecasting potential safety issues up to six months ahead and precisely identifying the best timing for wheel turning.”

For decades, Professor Tam has been collaborating with MTR, and his Smart Railway Research Laboratory boasts a life-sized train and track model, a generous contribution from MTR, which serves as a resource for research and educational activities.

“Our system is also installed on the Automated People Mover (APM) at Hong Kong International Airport," Professor Tam stated with pride. APM trains operate by drawing electricity from the power rail located on the side and secured by the grid poles. However, there is a risk of losing contact as the grid poles may shift over time, especially at curved sections. This could disrupt the power supply and interrupt train operation. Professor Tam's optical fibre sensing network monitors these conditions along the entire APM line, ensuring a consistent power flow to the APM and minimising service disruption.

Breaking Barriers: Flexible Applications and Lower Costs with Optical Fibre Technology

In addition to their versatile applications, optical fibres are also known for their comparatively lower expenses, particularly when monitoring large-scale systems.

Conventional cable sensors have a restricted range, capable of sensing merely sections of track spanning tens of meters. Moreover, they necessitate the use of amplifiers and repeaters that can accommodate only a limited number of sensors simultaneously and are prone to disruption from the electromagnetic fields produced by trains and the overhead lines.

On the other hand, optical fibre sensors can accurately monitor thousands of meters of track with minimal interference from external environmental conditions. This makes optical fibre technology significantly superior in practical applications.

"Railways require nightly maintenance, and installing thousands of conventional sensors within a short time frame is practically impossible," Professor Tam shared. He explained how optical fibre technology has revolutionised railway maintenance, "While the cost of an individual optical fibre sensor might be higher, the overall system cost can be significantly lower – sometimes by more than several tens of time – compared to conventional sensing systems."

Each MTR train is equipped with independent Radio Frequency Identification (RFID) technology, allowing optical fibre sensors to monitor the operational status of each individual train.

Professor Tam's optical fibre sensing system was also utilised to monitor the construction progress of Canton Tower in Guangzhou. By installing sensors at strategic locations on the Tower, deflections in construction can be detected via fibre sensors, aiding in the construction of the Tower's innovative twisted design.

Bridge Health Monitoring: Expanding the Applications of Optical Fibre Technology

Demonstrating its versatility beyond railway applications, the optical fibre sensing network has been integrated into the pedestrian footbridge connecting PolyU's new and old campuses, providing an additional layer of safety for the public.

"We were involved in every stage of the footbridge's design, construction, and implementation, ensuring that the monitoring system was seamlessly integrated from the start," Professor Tam explained. Spanning multiple lanes of busy traffic, the footbridge incorporates an optical fibre sensing network to monitor structural vibrations caused by extreme weather conditions or vehicular traffic. This system can detect even subtle changes that could potentially affect the bridge's safety, providing early warnings to the relevant authorities.

“The footbridge's design is already highly sophisticated, but the integration of optical fibre technology represents a technological advancement that also demonstrates the potential of this technology for bridge maintenance and the overall health management of public infrastructure," Professor Tam added.

Optical Fibre Technology in Medicine: Improving Hearing Loss Treatment and Rehabilitation

Optical fibre sensing technology is playing a crucial role in advancing personal medical devices, improving treatment outcomes for patients.

One ground-breaking application is in cochlear implants, which represent the primary surgical option for restoring hearing in individuals with hearing loss. During cochlear implantation surgery, surgeons carefully insert a tiny electrode device into the inner ear, where it delivers signals to stimulate the auditory nerve at precise locations to achieve the desired restoration of hearing.

However, cochlear implantation surgery is extremely expensive due to the high level of precision required. The electrode device must be inserted into the inner ear at a precise angle to avoid damaging delicate nerves and causing permanent trauma. Moreover, the device must be positioned accurately in relation to the auditory nerve to ensure proper sound reception. The complexity of the surgery contributes to its significant cost, ranging from hundreds of thousands to over a million dollars per operation.

"The human inner ear is spiral-shaped, with some areas measuring less than 0.5 millimeters in width," Professor Tam explained. "This necessitates extreme precision when inserting the electrode device to avoid damaging delicate nerves. The success of the surgery relies heavily on the surgeon's experience and skill." This challenge, however, has been addressed through the integration of optical fibre sensors.

"We place optical fibre sensors within the electrode device, enabling real-time monitoring of its position within the inner ear during surgery," Professor Tam stated. "This not only prevents injury but also improves the accuracy of targeting the auditory nerve locations." Professor Tam's research team is currently collaborating with professors and surgeons from the University of Melbourne in Australia to bring this innovative technology to clinical application.

"Previously, this technology was impractical due to the unsuitability of optical fibre sensor materials for human use. Traditional optical fibre sensors, made of glass, cannot withstand the small bending radius required in the inner ear and may cause internal injuries," Professor Tam explained. "PolyU is among the few institutions worldwide with in-house optical fibre drawing facilities, enabling us to develop optical fibres using materials suitable for human applications, such as cochlear implants."

With fibre sensing technology enabling precise electrode device positioning, cochlear implantation surgery no longer relies solely on the surgeon's experience and skill. This advancement has inspired Professor Tam's next research initiative: integrating robotics into the surgical process. The aim is to significantly reduce surgical costs, making the procedure more accessible to a broader range of patients and improving global well-being.

 

The applications of fibre sensing technology extend beyond cochlear implants to orthopedic devices.

For patients with bone injuries requiring fixators, timely and appropriate mobilisation of muscles and bones is crucial for full rehabilitation. Currently, determining the timing and intensity of movement relies heavily on subjective patient feedback and the doctor's experience. By incorporating optical fibre sensors into fixators, rehabilitation progress can be objectively monitored, allowing for more accurate guidance.

"Optical fibre sensing technology also facilitates remote diagnosis, reducing the need for frequent hospital visits and making the treatment process more comfortable and convenient for patients," Professor Tam added. This innovation not only enhances treatment efficacy but also significantly improves patients' quality of life during the recovery process.

Installing optical fibre sensors on the fixator enables the monitoring of bone injury patients' recovery progress.

PolyU’s Exclusive Laboratory: Pioneering Innovative Optical Fibre Materials

The versatility of optical fibre technology stems from the ability to tailor materials to specific applications. PolyU houses a specialised research laboratory with the capability of fabricating unique optical fibres from a diverse range of materials, placing them at the forefront of this field.

"I enjoy continuously experimenting in the lab with new materials to see what breakthroughs we can achieve," Professor Tam noted, pointing to a specialised optical fibre sensor for the MTR. "We fabricated these devices specifically for their unique specifications within our laboratory."

Professor Tam's passion for optical fibre technology, coupled with the advanced laboratory facilities, has been instrumental in driving the widespread adoption and innovation in fibre sensor applications.

PolyU's Speciality Optical Fibre Fabrication Laboratory.

 

 

Professor Tam (left), the developer of optical fibre sensing system for MTR, and Professor Lu Chao (right), Director of the Photonics Research Institute, posing together in front of a sensor fabrication equipment.

Professor Tam's dedication has led to the significant development of optical fibre sensor applications.