title: Nano-Anatase TiO₂ for High Performance Optical Humidity Sensing on Chip.
abstract: An on-chip optical humidity sensor using Nano-anatase TiO₂ coating is presented here. The coating material was prepared so that the result is in solution form, making the fabrication process quick and simple. Then, the solution was effortlessly spin-coated on an SU8 straight channel waveguide. Investigating the sensitivity and performance (response time) of the device revealed a great linearity in the wide range (35% to 98%) of relative humidity (RH). In addition, a variation of more than 14 dB in transmitted optical power was observed, with a response time of only ~0.7 s. The effect of coating concentration and UV treatment was examined on the performance and repeatability of the sensor. Interesting observations were found, and the attributed mechanisms were described. In addition, the proposed sensor was extensively compared with other state-of-the-art proposed counterparts from the literature and remarkable advantages were found. Since a high sensitivity of ~0.21 dB/%RH and high dynamic performances were demonstrated, this sensor is proposed for use in biomedical applications.
authors.affiliation: Photonics Research Center, University of Malaya, Kuala Lumpur 50603, Malaysia. mahdiar@um.edu.my.
authors.forename: Mahdiar
authors.initials: M
authors.lastname: Ghadiry
authors.affiliation: Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia. gholami897@gmail.com.
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Gholami
authors.affiliation: Photonics Research Center, University of Malaya, Kuala Lumpur 50603, Malaysia. laichoonkong@gmail.com.
authors.forename: Lai Choon
authors.initials: LC
authors.lastname: Kong
authors.affiliation: Photonics Research Center, University of Malaya, Kuala Lumpur 50603, Malaysia. WuYi@um.edu.my.
authors.forename: Chong Wu
authors.initials: CW
authors.lastname: Yi
authors.affiliation: Photonics Research Center, University of Malaya, Kuala Lumpur 50603, Malaysia. Harith@um.edu.my.
authors.forename: Harith
authors.initials: H
authors.lastname: Ahmad
authors.affiliation: Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia. Yatima@um.edu.my.
authors.forename: Yatima
authors.initials: Y
authors.lastname: Alias
keywords: evanescence field; humidity sensing; nano-anatase TiO2; optic sensor; waveguide