PMID- 27101247
OWN - NLM
STAT- MEDLINE
DCOM- 20170313
LR  - 20231111
IS  - 1932-6203 (Electronic)
IS  - 1932-6203 (Linking)
VI  - 11
IP  - 4
DP  - 2016
TI  - Ultra-Sensitive Humidity Sensor Based on Optical Properties of Graphene Oxide and 
      Nano-Anatase TiO2.
PG  - e0153949
LID - 10.1371/journal.pone.0153949 [doi]
LID - e0153949
AB  - Generally, in a waveguide-based humidity sensors, increasing the relative 
      humidity (RH) causes the cladding refractive index (RI) to increase due to 
      cladding water absorption. However, if graphene oxide (GO) is used, a reverse 
      phenomenon is seen due to a gap increase in graphene layers. In this paper, this 
      interesting property is applied in order to fabricate differential humidity 
      sensor using the difference between RI of reduced GO (rGO) and nano-anatase TiO2 
      in a chip. First, a new approach is proposed to prepare high quality nano-anatase 
      TiO2 in solution form making the fabrication process simple and straightforward. 
      Then, the resulted solutions (TiO2 and GO) are effortlessly drop casted and 
      reduced on SU8 two channels waveguide and extensively examined against several 
      humid conditions. Investigating the sensitivity and performance (response time) 
      of the device, reveals a great linearity in a wide range of RH (35% to 98%) and a 
      variation of more than 30 dB in transmitted optical power with a response time of 
      only ~0.7 sec. The effect of coating concentration and UV treatment are studied 
      on the performance and repeatability of the sensor and the attributed mechanisms 
      explained. In addition, we report that using the current approach, devices with 
      high sensitivity and very low response time of only 0.3 sec can be fabricated. 
      Also, the proposed device was comprehensively compared with other state of the 
      art proposed sensors in the literature and the results were promising. Since high 
      sensitivity ~0.47dB/%RH and high dynamic performances were demonstrated, this 
      sensor is a proper choice for biomedical applications.
FAU - Ghadiry, Mahdiar
AU  - Ghadiry M
AD  - Photonics Research Center, University of Malaya, Kuala Lumpur, 50603, Malaysia.
FAU - Gholami, Mehrdad
AU  - Gholami M
AD  - Department of Chemistry, Marvdasht Branch, Islamic Azad University, P.O. Box 465, 
      Marvdasht, Iran.
FAU - Lai, C K
AU  - Lai CK
AD  - Photonics Research Center, University of Malaya, Kuala Lumpur, 50603, Malaysia.
FAU - Ahmad, Harith
AU  - Ahmad H
AD  - Photonics Research Center, University of Malaya, Kuala Lumpur, 50603, Malaysia.
FAU - Chong, W Y
AU  - Chong WY
AD  - Photonics Research Center, University of Malaya, Kuala Lumpur, 50603, Malaysia.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20160421
PL  - United States
TA  - PLoS One
JT  - PloS one
JID - 101285081
RN  - 0 (Oxides)
RN  - 15FIX9V2JP (titanium dioxide)
RN  - 7782-42-5 (Graphite)
RN  - D1JT611TNE (Titanium)
SB  - IM
MH  - Graphite/*chemistry
MH  - *Humidity
MH  - Metal Nanoparticles/*chemistry
MH  - Microscopy, Electron, Scanning
MH  - Oxides/*chemistry
MH  - Powder Diffraction
MH  - Spectrum Analysis, Raman
MH  - Titanium/*chemistry
PMC - PMC4839738
COIS- Competing Interests: The authors have declared that no competing interests exist.
EDAT- 2016/04/23 06:00
MHDA- 2017/03/14 06:00
PMCR- 2016/04/21
CRDT- 2016/04/22 06:00
PHST- 2015/11/12 00:00 [received]
PHST- 2016/04/06 00:00 [accepted]
PHST- 2016/04/22 06:00 [entrez]
PHST- 2016/04/23 06:00 [pubmed]
PHST- 2017/03/14 06:00 [medline]
PHST- 2016/04/21 00:00 [pmc-release]
AID - PONE-D-15-49451 [pii]
AID - 10.1371/journal.pone.0153949 [doi]
PST - epublish
SO  - PLoS One. 2016 Apr 21;11(4):e0153949. doi: 10.1371/journal.pone.0153949. 
      eCollection 2016.