Optical Fibres a Cheaper and More Efficient Component for Humidity Sensors

January 14, 2021

Fibre optic cables are known to many of us as what allows us to enjoy high speed internet connections. Optical fibres have been used for various applications such as transmissions, but they have since gained tremendous interest as a component in relative humidity sensors.


While current sensing probes use electricity, it has been discovered that the advantage of using microfibers in relative humidity sensors is that the sensing element can be fabricated using inexpensive components with a variety of coating materials.

Relative humidity sensors are one of the most commonly used instruments in environmental monitoring. Measuring humidity within an environment can be critical in many industries such as biomedical, food processing, pharmaceuticals, meteorology, microelectronics, agriculture, aviation and more, because of how it can affect the health and safety of personnel as well as the cost of a product.

While current sensing probes use electricity, it has been discovered that the advantage of using microfibers in relative humidity sensors enables the sensing element to be fabricated using inexpensive components with a variety of coating materials.

A research by Associate Professor Ir. Dr. Malathy Batumalay from INTI International University’s Faculty of Information Technology on the behaviour of coated materials on microfibers for relative humidity sensing found that it reacted to changes in humidity.

“Fibre optics is famous as transmission cables and it carries light with high speeds. During my PhD research in 2012, I converted fibre optics into a sensor. A very small length of fibre optics was tapered and when exposed to its surroundings, some changes in the light travel could be detected. This is what made me research further,” said Dr. Malathy who received a RM20,000 INTI Seed Grant to conduct her study from July 2020 to June 2021. The study is a collaboration with Professor Ir. Dr. Sulaiman Wadi Harun from University Malaya.

After finding that the tapered region could react to changes in temperature, relative humidity, concentration of liquid and also gases, Dr. Malathy proceeded to explore the effect of various coating materials such as graphene, carbon nano tubes, HEC PVDF, agarose gel, and zinc oxide which enhanced the performance of sensor.

According to Dr. Malathy, who works actively in the area of photonics engineering, the findings from her research will be used to add to theoretical findings and have helped other researchers around the world to support and further explore their own findings.


Associate Professor Ir. Dr. Malathy Batumalay from INTI International University’s Faculty of Information Technology said she looks forward to having the theoretical findings from her research work to one day be added to book chapters which will improve the quality of teaching and understanding about the nature of fibre optic sensors.

“This field of study will give a new approach to how a fiber optic cable can be converted into sensors which work as detection probes. In the future, this could be extended into smart devices when incorporated into IoT (Internet of Things),” she said.

Dr. Malathy, who is a third time recipient of the RM20,000 internal research grant from INTI International University, has also previously collaborated with Prof. Sulaiman on projects titled “Graphene as a Saturable Absorber for Pulsed Fiber Laser Development” and “Tapered Fiber Sensors to Detect Live Cells and changes in Relative Humidity”. In July 2020, she started her journey on a project titled “A Study on the Effect of Microbottle Resonator for Relative Humidity Sensing”. As part of this research work, she presented one of her publications at an International Conference organized by I-COSINE 2020 and won the best presenter award.

When asked what she looks forward to most on her research journey, Dr. Malathy shared that completing a fundamental study means that it can be added to syllabus content.

“Research in fibre sensor development is expanding to support new applications. The theoretical findings from my research work can be added to book chapters which I believe will improve the quality of teaching and understanding about the nature of fibre optic sensors. I really look forward to this,” she concluded.