Optical fiber proximity sensor for micro distance measurement

This paper demonstrates an optical fiber proximity sensor for micro distance measurement. The optical fiber was used to detect a silver plate which acted as an obstacle. A flat end of a standard single mode optical fiber was functioned to emit the broadband light at near infrared wavelength region and receive the reflected light from the obstacle. The distance between the optical fiber and the obstacle was varied from 0μm to 400 μm. We experimentally characterized the sensor sensitivity based on their free spectral range. The optical fiber tip has shown its potential for proximity sensing application with sensitivity value of 0.0199 nm μm and regression value up to 0.9126

Preliminary evaluation of indoor thermal comfort in Malaysia heritage mosque

Malaysia heritage buildings are the country's architectural gems. Among them is the religious building such as mosque. The Malaysia heritage mosque is normally built in response to the local culture and environment. Unlike most of Malaysia modern mosques where air conditioning is opted as ventilation mode, the heritage mosques achieve indoor thermal comfort via the passive architectural design. Due to that, this study was executed with the purpose of investigating the indoor thermal comfort of a Malaysia heritage mosque located at traditional street in Melaka, namely Masjid Tanah. The methodology used in the study was field measurement, in which the parameters measured were the indoor and outdoor air temperatures. The field measurement was conducted for two days in the end of March and early of April 2018, from 9 am to 4 pm. The indoor predicted comfort temperature was derived using the adaptive model. The findings indicated that the measured indoor air temperatures were lower than the indoor predicted comfort temperatures at most of the time. Therefore, it shows that the passive architectural design adopted by the Malaysia heritage mosque, which is Masjid Tanah, is able to provide indoor thermal comfort to the users

Liquid level monitoring with single layered rubber diaphragm fibre Bragg grating sensor

Liquid level monitoring is essential for the industry. Conventional electronic sensor for this application is susceptible to electrical and heat conductivity that is risky for flammable substances. Hence, this paper introduces a single-layered rubber diaphragm fiber Bragg grating sensor to overcome this matter. In this experiment, the sensor used a straining mechanism as a sensing effect to monitor the liquid level ranging from 0-1200 ml. The result shows that the Bragg wavelength shifted towards the longer region when increasing the liquid level. The sensor exhibited an average sensitivity of 0.0042 nm/ml and average linearity of 96.376%, promising a good result for liquid level monitoring

Graphene coated optical fiber tip sensor for nitrate sensing application

An optical fiber tip sensing probe coated with graphene is proposed for nitrate-sensing application. The sensor was coated with graphene using dip-casting method to detect nitrate at different concentrations ranging from 0 to 50 ppm. The graphene-coated fiber tip sensor was highly sensitive in detecting nitrate ion. When the concentration of the nitrate solution was dropped onto the sensing region, the reflected optical power decreased as the nitrate concentration increased. Without the graphene layer, the uncoated fiber tip sensor only had a sensitivity of 0.0076 dBm/ppm. However, the coated sensor's sensitivity was significantly enhanced to 0.0624 dBm/ppm, eight times higher than the uncoated fiber tip sensor, mainly due to the adsorption of nitrate on the graphene surface. This graphene-coated optical fiber tip sensor has a high potential to be used in nitrate-sensing applications