Publication:
Integrated humidity sensor based on SU-8 polymer microdisk microresonator

dc.contributor.coauthorY. Karadag
dc.contributor.coauthorN. Kilinc
dc.contributor.departmentDepartment of Mechanical Engineering
dc.contributor.departmentDepartment of Physics
dc.contributor.departmentGraduate School of Sciences and Engineering
dc.contributor.departmentKUYTAM (Koç University Surface Science and Technology Center)
dc.contributor.kuauthorAlaca, Burhanettin Erdem
dc.contributor.kuauthorAnand, Suman
dc.contributor.kuauthorEryürek, Mustafa
dc.contributor.kuauthorKiraz, Alper
dc.contributor.kuauthorTaşdemir, Zuhal
dc.contributor.schoolcollegeinstituteCollege of Engineering
dc.contributor.schoolcollegeinstituteCollege of Sciences
dc.contributor.schoolcollegeinstituteGRADUATE SCHOOL OF SCIENCES AND ENGINEERING
dc.contributor.schoolcollegeinstituteResearch Center
dc.date.accessioned2024-11-09T23:35:26Z
dc.date.issued2017
dc.description.abstractDue to its high interaction with water vapor and photolithographic patterning property, SU-8 is a favorable hygroscopic polymer for developing humidity sensors. In addition, optical resonances of optical microresonators are very sensitive to the dianges in their environment. Here, we present integrated optical humidity sensors based on chips containing SU-8 polymer microdisks and waveguides fabricated by single-step UV photolithography. The performance of these sensors is tested under a wide range of relative humidity (RH) levels (0-50%). A tunable laser light is coupled from an excitation fiber to individual SU-8 waveguides using end-face coupling method. As the laser wavelength is scanned, the whispering gallery modes (WGMs) are revealed as dips in the transmission spectra. Sensing is achieved by recording spectral shifts of the WGMs of the microdisk microresonators. Red shift is observed in the WGMs with increasing RH. Between 0 and 1% RH, an average spectral shift sensitivity of 108 pm/% RH is demonstrated from measurements performed on 4 sensor devices. This sensitivity is comparable to the highest values obtained using microresonators in the literature. Measurements performed with another sensor device revealed a decrease in sensitivity by only around 3 times when RH is increased to 45-50%. Finite element modeling simulations are carried out to determine the dominant effect responsible for the resonance shift. The results show that the refractive index change is more important than the microresonator size change. The standard deviation in wavelength measurement is <3 pm, indicating a limit of detection better than 0.03% RH. These results suggest that optical sensor devices that contain integrated SU-8 microresonators and waveguides can be employed as easy-to-fabricate and sensitive humidity sensors. (C) 2016 Elsevier B.V. All rights reserved.
dc.description.indexedbyWOS
dc.description.indexedbyScopus
dc.description.openaccessNO
dc.description.sponsoredbyTubitakEuN/A
dc.description.sponsorshipTUBITAK [110T803, 115F446] We acknowledge financial support from TUBITAK (grant no. 110T803 and 115F446) and thank Alexandr Jonas for proofreading the manuscript.
dc.description.volume242
dc.identifier.doi10.1016/j.snb.2016.09.136
dc.identifier.issn0925-4005
dc.identifier.scopus2-s2.0-85011371500
dc.identifier.urihttps://doi.org/10.1016/j.snb.2016.09.136
dc.identifier.urihttps://hdl.handle.net/20.500.14288/12502
dc.identifier.wos393267700137
dc.keywordsMicrodisk
dc.keywordsWhispering gallery mode
dc.keywordsSU-8
dc.keywordsFEM
dc.keywordsHumidity sensor
dc.keywordsMicroresonator
dc.language.isoeng
dc.publisherElsevier Science Sa
dc.relation.ispartofSensors And Actuators B-Chemical
dc.subjectChemistry
dc.subjectAnalytical
dc.subjectElectrochemistry
dc.subjectInstruments
dc.subjectInstrumentation
dc.titleIntegrated humidity sensor based on SU-8 polymer microdisk microresonator
dc.typeJournal Article
dspace.entity.typePublication
local.contributor.kuauthorEryürek, Mustafa
local.contributor.kuauthorTaşdemir, Zuhal
local.contributor.kuauthorAnand, Suman
local.contributor.kuauthorAlaca, Burhanettin Erdem
local.contributor.kuauthorKiraz, Alper
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