Nano-Anatase TiO2 for High Performance Optical Humidity Sensing on Chip

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.

[1]  Razali Ismail,et al.  A new approach to model sensitivity of graphene-based gas sensors , 2015 .

[2]  Zhaoxiong Xie,et al.  High-sensitivity humidity sensor based on a single SnO(2) nanowire. , 2007, Journal of the American Chemical Society.

[3]  D. Y. Kim,et al.  Ultrasensitive chemiresistors based on electrospun TiO2 nanofibers. , 2006, Nano letters.

[4]  R. N. Karekar,et al.  Humidity sensor using planar optical waveguides with claddings of various oxide materials , 1997 .

[5]  H. Ahmad,et al.  Graphene oxide-based waveguide polariser: from thin film to quasi-bulk. , 2014, Optics express.

[6]  J. Bravo,et al.  Optical Fiber Humidity Sensors Using Nanostructured Coatings of SiO$_{2}$ Nanoparticles , 2008, IEEE Sensors Journal.

[7]  Antonio Quintela Incera,et al.  Fiber Optic Sensors in Structural Health Monitoring , 2011, Journal of Lightwave Technology.

[8]  Desheng Jiang,et al.  Zinc oxide nanorod and nanowire for humidity sensor , 2005 .

[9]  R. Ismail,et al.  Sensitivity Modelling of Graphene Nanoscroll-Based NO2 Gas Sensors , 2015, Plasmonics.

[10]  Jani Kivioja,et al.  Ultrafast graphene oxide humidity sensors. , 2013, ACS nano.

[11]  A. Gaston,et al.  Evanescent wave optical-fiber sensing (temperature, relative humidity, and pH sensors) , 2003 .

[12]  H. Guerrero,et al.  High-sensitivity sensor of low relative humidity based on overlay on side-polished fibers , 2004, IEEE Sensors Journal.

[13]  Min Zhang,et al.  Long-Period Grating Relative Humidity Sensor With Hydrogel Coating , 2007, IEEE Photonics Technology Letters.

[14]  Harith Ahmad,et al.  All-Optical Graphene Oxide Humidity Sensors , 2014, Sensors.

[15]  L. Petti,et al.  Optical waveguide humidity sensor with symmetric multilayer configuration , 2001 .

[16]  A. Fujishima,et al.  TiO2 Photocatalysis: A Historical Overview and Future Prospects , 2005 .

[17]  Isaac Newton.  Enhanced gas sensing performance of TiO 2 functionalized Magneto Optical SPR sensors , 2011 .

[18]  M. Dresselhaus,et al.  Ultrahigh humidity sensitivity of graphene oxide , 2013, Scientific Reports.

[19]  R Aneesh,et al.  Zinc oxide nanoparticle based optical fiber humidity sensor having linear response throughout a large dynamic range. , 2011, Applied optics.

[20]  K. Hashimoto,et al.  Enhancement of Photoinduced Highly Hydrophilic Conversion on TiO2 Thin Films by Introducing Tensile Stress , 2003 .

[21]  Subi J. George,et al.  Ultrafast response humidity sensor using supramolecular nanofibre and its application in monitoring breath humidity and flow , 2014, Scientific Reports.

[22]  S. Khijwania,et al.  Titanium dioxide nanoparticle based optical fiber humidity sensor with linear response and enhanced sensitivity. , 2012, Applied optics.

[23]  M. G. Manera,et al.  Enhanced gas sensing performance of TiO2 functionalized magneto-optical SPR sensors , 2011 .

[24]  George Stewart,et al.  Sensitivity improvement for evanescent-wave gas sensors , 1993 .

[25]  Zhiping Xu,et al.  Understanding water permeation in graphene oxide membranes. , 2014, ACS applied materials & interfaces.

[26]  A. Vijayan,et al.  Optical fibre based humidity sensor using Co-polyaniline clad , 2008 .

[27]  T. L. Yeo,et al.  Characterisation of a polymer-coated fibre Bragg grating sensor for relative humidity sensing , 2005 .

[28]  Zhixian Zhou,et al.  Carbon dioxide gas sensor using a graphene sheet , 2011 .

[29]  J. Mathew.  Development of Novel Fiber Optic Humidity Sensors and Their Derived Applications , 2013 .

[30]  Minghong Yang,et al.  Optical fiber relative-humidity sensor with evaporated dielectric coatings on fiber end-face , 2014 .

[31]  Harianto Rahardjo,et al.  High relative humidity measurements using gelatin coated long-period grating sensors , 2005 .

[32]  T. L. Yeo,et al.  Fibre-optic sensor technologies for humidity and moisture measurement , 2008 .