04653ntm a2200397 i 4500952014100000952012400141999001700265003000800282005001700290006001900307007000300326008004100329020003200370040002300402090002900425100002800454245010500482264003400587264001200621300007000633336002100703336002100724337002500745337002300770338002300793338003000816347002400846500006400870502007300934504004001007520305701047610007904104650004504183650001104228942001604239  00102lcc40708REFa20000b20000cREFd2022-04-18l0oFTKMA .V67 2021 r ThesispT000001860r2022-06-09 00:00:00t1w2022-04-18yTHESIS  00102lcc40708REFa20000b20000cREFd2022-04-18l0oCD13096pT000001861r2022-04-18 00:00:00t1w2022-04-18yTHESIS  c97057d97063MY-KuUP20251125110037.0t||||fr|||| 000 0 ta220418s2021    my a|||frm||| 000 0 eng d  aTHE0009339(Local)qhardback  aUMPbengcUMPerda  aFTKMA .V67 2021 r Thesis1 aVorathin Epin,eauthor.10aAccuracy improvement of rubber-based diaphragm fibre bragg grating pressure sensors /cVorathin Epin 1aKuantan, Pahang :bUMP,c2021 4c© 2020  axx, 205 pages :billustrations (some color) ;c30 cm. +e1 CD ROM  atext2rdacontent  atext2rdacontent  aunmediated2rdamedia  acomputer2rdamedia  avolume2rdacarrier  acomputer disc2rdacarrier  atext filebPDF2rda  aFaculty of Mechanical and Automotive Engineering Technology  aThesis (Doctor of Philosophy) -- Universiti Malaysia Pahang – 2021  aIncludes bibliographical references3 aWater level sensing has  become a great  importance  in various industrial applications.  Due  to  its  advantages,  fibre  Bragg  grating  (FBG)  pressure  sensor  has  been  introduced  to  overcome the drawbacks  of electrical pressure sensor for hydrostatic pressure  based water  level sensing.  Over the years, various studies  have been reported on the use of rubberbased diaphragms  to increase the pressure sensitivity of the bare FBG pressure sensors.  However, high thermal  expansion of the rubber  material is making the FBG pressure  sensors  more  sensitive  to  the  temperature  effects  due  to  the  increased  temperature  sensitivity.  This drawback can result  in inaccuracy of the  pressure sensors. Therefore, the  main objective of this study is to eliminate the temperature sensitivity  in order to improve  the accuracy of the rubber-based diaphragm FBG pressure sensors.  Here, four types of  pressure sensors  were developed to investigate the temperature effects. Type I pressure  sensor was simply by bonding the bare FBG on rubber diaphragm without temperature  compensation.  Type  II  pressure  sensor  was  similar  to  type  I  but  with  reference  FBG  temperature compensation technique. Type III and type IV pressure sensors  were based  on  differential  FBG  and  bandwidth  modulation  technique.  All  pressure  sensors  underwent pressure and temperature variations. Under pressure variation across 20 kPa,  all the pressure sensors obtained high pressure sensitivity at 274.8 pm/kPa, 275.0 pm/kPa,  641.9 pm/kPa and -275.1 pm/kPa. Besides, type IV pressure sensor is also capable to be  monitored using photodetector (PD) with the pressure sensitivity of -12.1  mV/kPa. Under  temperature  variation  across  50  °C,  all  pressure  sensors  obtained  high  temperature  sensitivity  of  more  than  44.0  pm/°C  when  monitored  based  on  single  wavelength.  However, the differential FBG and bandwidth modulation techniques obtained negligible average  temperature  sensitivity  at  only  0.5  pm/°C  and  -0.3  pm/°C.  Due  to  this,  the  measured pressure and water level using type I and type II pressure sensors was far off  from the actual readings with the percentage of error at 35% and 16.55%. Type III and  type IV pressure sensors obtained an  average highest percentage of accuracy error at only  3.24%  and  5.51%.  This  is  because  the  temperature  effects  have  no  influence  on  temperature  insensitive  pressure  sensors.  As  a  conclusion,  the  findings  of  this  study  shows that the use of rubber diaphragm with differential FBG and bandwidth modulation  techniques  capable  to  eliminate  away  the  temperature  sensitivity  and  retain  the  high  pressure sensitivity of the pressure sensors. The temperature-independent high pressure  sensitivity characteristics enabled the pressure sensors to be used for low pressure sensing  in the fields of hydrology, agriculture, food processing and water supply system with  better accuracy and reducing false information20aFaculty of Mechanical and Automotive Engineering TechnologyxDissertations 0aUniversities and collegesxDissertations 0aTheses  2lcccTHESIS