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  • 201. Shah Alam, M.
    et al.
    Mohammed, W. S.
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM. Center of Excellence in Nanotechnology, Asian Institute of Technology, 12120 Pathumthani, Thailand.
    Multilayered gold/silica nanoparticulate bilayer devices using layer-by-layer self organisation for flexible bending and pressure sensing applications2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 104, no 7, article id 073106Article in journal (Refereed)
    Abstract [en]

    A pressure and bending sensor was fabricated using multilayer thin films fabricated on a flexible substrate based on layer-by-layer self-organization of 18 nm gold nanoparticles separated by a dielectric layer of 30 nm silica nanoparticles. 50, 75, and 100 gold-silica bi-layered films were deposited and the device characteristics were studied. A threshold voltage was required for electron conduction which increases from 2.4 V for 50 bi-layers to 3.3 V for 100 bi-layers. Upon bending of the device up to about 52°, the threshold voltage and slope of the I-V curves change linearly. Electrical characterization of the multilayer films was carried out under ambient conditions with different pressures and bending angles in the direct current mode. This study demonstrates that the developed multilayer thin films can be used as pressure as well as bending sensing applications.

  • 202. Sivapunniyam, Aarthy
    et al.
    Wiromrat, Niti
    Zar Myint, Myo Tay
    Dutta, Joydeep
    Asian Institute of Technology, Center of Excellence in Nanotechnology, Thailand.
    High-performance liquefied petroleum gas sensing based on nanostructures of zinc oxide and zinc stannate2011In: Sensors and Actuators B: Chemical, ISSN 0925-4005, Vol. 157, no 1, p. 232-239Article in journal (Refereed)
  • 203. Sugunan, A.
    et al.
    Melin, P.
    Schnürer, J.
    Hilborn, J. G.
    Dutta, Joydeep
    Nutrition-driven assembly of colloidal nanoparticles: Growing fungi assemble gold nanoparticles as microwires2007In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 19, no 1, p. 77-81Article in journal (Refereed)
  • 204. Sugunan, A.
    et al.
    Thanachayanont, C.
    Dutta, Joydeep
    School of Advanced Technologies, Asian Institute of Technology, Thailand.
    Hilborn, J. G.
    Heavy-metal ion sensors using chitosan-capped gold nanoparticles2005In: Science and Technology of Advanced Materials, ISSN 1468-6996, E-ISSN 1878-5514, Vol. 6, no 3-4 SPEC. ISS., p. 335-340Article in journal (Refereed)
    Abstract [en]

    We report a novel strategy for using gold nanoparticles capped with chitosan for sensing ions of heavy metals. Acidic anions (glutamate ions in our case) are expected to cap the nanoparticle surfaces similar to conventional methods of stabilization of gold nanoparticles by citrate ions. The polycationic nature of chitosan enables attachment of the polymer to the negatively charged gold nanoparticle surfaces through electrostatic interactions. Use of chitosan serves dual purpose of providing sufficient steric hindrance ensuring stability of the colloid and also to functionalize the nanoparticles for use as sensors. The well-documented chelating properties of chitosan and the sensitivity of the optical properties of gold nanoparticles to agglomeration have been employed to detect low concentrations of heavy metals ions (Zn2+ and Cu2+) in water. A comparison of the optical absorption spectra of the colloidal suspension before and after exposure to metal ions is a good indicator of the concentration of the heavy metal ions.

  • 205. Sugunan, Abhilash
    et al.
    Dutta, Joydeep
    Novel synthesis of gold nanoparticles in aqueous media2005In: Materials Research Society Symposium Proceedings, 2005, p. 257-262Conference paper (Refereed)
    Abstract [en]

    Aqueous synthesis of glutamate functionalized single crystal gold nanoparticles was achieved by reducing a solution of chloroauric acid with monosodium glutamate. Highly uniform size distributions of the nanoparticles can be obtained by having an excess of monosodium glutamate in the starting solution. Similar to the conventional synthesis of gold nanoparticles by reduction of chloroauric acid with trisodium citrate, the obtained particle sizes were varied in the range of 14 - 25 nm without loosing the uniformity in its size distribution by varying the concentration of the reducing agent. © 2006 Materials Research Society.

  • 206. Sugunan, Abhilash
    et al.
    Warad, Hemant C.
    Boman, Mats
    Dutta, Joydeep
    Zinc oxide nanowires in chemical bath on seeded substrates: Role of hexamine2006In: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 39, no 1, p. 49-56Article in journal (Refereed)
  • 207. Teerapanich, Pattamon
    et al.
    Myint, Myo Tay Zar
    Joseph, Claire M
    Hornyak, Gabor L
    Dutta, Joydeep
    Sultan Qaboos University, Oman.
    Development and improvement of carbon nanotube based ammonia gas sensors using ink-jet printed interdigitated electrodes2013In: IEEE transactions on nanotechnology, ISSN 1536-125X, E-ISSN 1941-0085, Vol. 12, no 2, p. 255-262Article in journal (Refereed)
    Abstract [en]

    Gas sensors have been widely used in many applications including environmental monitoring, industrial control, and detection in warfare or for averting security threats. High sensitivity, selectivity, and fast response time are required for application in real-time monitoring and detection of toxic gases. Single-walled carbon nanotubes (SWCNTs) provide large specific surface area beneficial for gas adsorption thereby increasing sensor sensitivity. In this paper, ammonia (NH3) gas sensors based on SWCNTs were developed using interdigitated silver electrodes printed with nanoparticulate ink on alumina substrates. Simple and inexpensive methods including shaking and dispersion in appropriate solvents were used to debundle SWCNTs for improving sensor response. The fabricated sensors showed a maximum response of 27.3% for 500 ppm NH3 at room temperature. Detection limit of the sensor devices at room temperature were estimated to be similar to 3 ppm.

  • 208. Teesetsopon, Pichanan
    et al.
    Kumar, S
    Dutta, Joydeep
    Asian Institute of Technology, Thailand; Sultan Qaboos University, Oman.
    Photoelectrode Optimization of Zinc Oxide Nanoparticle Based Dye-Sensitized Solar Cell by Thermal Treatment2012In: International Journal of Electrochemical Science, ISSN 1452-3981, E-ISSN 1452-3981, Vol. 7, no 6, p. 4988-4999Article in journal (Refereed)
    Abstract [en]

    Interfacial properties at the photoelectrode of dye-sensitized solar cell (DSSC) play a vital role in determining its efficiency. This research examined the role of annealing temperature on the photoelectrode interfaces properties, and to find the annealing temperature that provides the highest overall solar cell efficiency. The electrical characteristics of the DSSC using ZnO nanoparticles photoelectrode annealed at different temperatures were studied using electrochemical impedance spectroscopy (EIS), and the corresponding I-V characteristics were determined. The highest efficiency of the solar cells was obtained when the photoelectrode was annealed at 400°C. This is mainly due to the enhancement in charge collection by better ZnO crystallinity and reduction of interfacial charge transfer resistance at the ZnO/dye/electrolyte interface. Moreover, the electron recombination between transparent conducting oxide substrate and electrolyte was also revealed for the first time by EIS.

  • 209.
    Tofa, Tajkia Syeed
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. Department of Civil and Environmental Engineering (CEE), Islamic University of Technology (IUT), Gazipur, Bangladesh.
    Laxman Kunjali, Karthik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Paul, Swaraj
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Visible light photocatalytic degradation of microplastic residues with zinc oxide nanorods2019In: Environmental Chemistry Letters, ISSN 1610-3653, E-ISSN 1610-3661, Vol. 17, no 3, p. 1341-1346Article in journal (Refereed)
    Abstract [en]

    Microplastics have recently become a major environmental issue due to their ubiquitous distribution, uncontrolled environmental occurrences, small sizes and long lifetimes. Actual remediation methods include filtration, incineration and advanced oxidation processes such as ozonation, but those methods require high energy or generate unwanted by-products. Here we tested the degradation of fragmented, low-density polyethylene (LDPE) microplastic residues, by visible light-induced heterogeneous photocatalysis activated by zinc oxide nanorods. The reaction was monitored using Fourier-transform infrared spectroscopy, dynamic mechanical analyser and optical imaging. Results show a 30% increase of the carbonyl index of residues, and an increase of brittleness accompanied by a large number of wrinkles, cracks and cavities on the surface. The degree of oxidation was directly proportional to the catalyst surface area. A mechanism for polyethylene degradation is proposed.

  • 210. Ullah, R.
    et al.
    Dutta, Joydeep
    Photocatalytic degradation of organic dyes with manganese-doped ZnO nanoparticles2008In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 156, no 1-3, p. 194-200Article in journal (Refereed)
  • 211. Vacassy, R.
    et al.
    Houriet, R.
    Plummer, C. J. G.
    Dutta, Joydeep
    Hofmann, H.
    Tin dioxide nano-powders for gas sensor applications1998In: Materials Research Society Symposium - Proceedings, 1998, p. 41-46Conference paper (Refereed)
    Abstract [en]

    SnO2 nanoparticles are of interest for gas sensor applications because the surface area is much larger compared to conventional powders. Thus, interactions between the material and the gases, which occur on the surface sites of the particles, are increased considerably. The preparation of SnO2 powders has been investigated following two forced precipitation systems: the hydrolysis reaction of SnCl4 in an emulsion media and the hydrolysis reaction of Sn2+ in the presence of a complexing ligand (CH3COO-). Spherical nanoparticles in the 10 to 100 nm range and with a narrow size distribution were synthesized by both precipitating routes. In both cases, it has been demonstrated that the most important parameter which controlled the particle size was the nature of the associated union. When this associated union or ligand is able to form a strong complex with the colloidal subunits, a barrier against Van der Waals attraction is created which results in little growth. This greatly influences the agglomeration/growth kinetics during the precipitation. The effect of acetate chelating ligands which resulted in the SnO2 nano-powders formed of 5-10 nm crystallites will be presented and discussed. Preliminary results on the gas (N2, NO) adsorption studies on pellets formed from these powders are also presented.

  • 212. Vacassy, R.
    et al.
    Lemaire, L.
    Valmalette, J. -C
    Dutta, Joydeep
    Swiss Fed. Institute of Technology, Switzerland .
    Hofmann, H.
    Synthesis of zirconia-coated gold nanoparticles1998In: Journal of materials science letters, ISSN 0261-8028, E-ISSN 1573-4811, Vol. 17, no 19, p. 1665-1667Article in journal (Refereed)
  • 213. Vacassy, R.
    et al.
    Scholz, S. M.
    Dutta, Joydeep
    Hofmann, H.
    Plummer, C. J. G.
    Carrot, G.
    Hilborn, J.
    Akinc, M.
    Nanostructured zinc sulphide phosphors1998In: Materials Research Society Symposium - Proceedings, 1998, p. 369-374Conference paper (Refereed)
    Abstract [en]

    Zinc sulphide (ZnS) particles are efficient phosphors for application in flat-panel displays. Spherical ZnS particles were prepared by precipitation from a homogeneous solution. Nanoparticles of 20 to 40 nm having a very narrow size distribution could be synthesized by using complexing chelates such as acetate and acetylacetonate. Complexing of the precipitating cation with the anions present in the system lead to a limited concentration of free cations in the solution. This strongly influences the kinetics of the primary particle agglomeration/growth, resulting in nanometer-sized ZnS particles. Nanostructured ZnS synthesized in this way are polycrystalline particles composed of crystallites of 5-10 nm. The synthesis of very small, non-agglomerated, nanocrystalline particles in the 5-10 nm size range was also possible, making use of a strong complexing ligand (thioglycerol) during the synthesis. The synthesis of controlled monosized ZnS particles will be presented and discussed. The photoluminescence characteristics of ZnS make this material a suitable candidate as phosphor for application in low voltage display technology. The effect of Mn2+ doping on the luminescence characteristics of ZnS will also be discussed.

  • 214. Vacassy, R.
    et al.
    Scholz, S. M.
    Dutta, Joydeep
    Swiss Fed. Institute of Technology, Switzerland.
    Plummer, C. J. G.
    Houriet, R.
    Hofmann, H.
    Synthesis of controlled spherical zinc sulfide particles by precipitation from homogeneous solutions1998In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 81, no 10, p. 2699-2705Article in journal (Refereed)
    Abstract [en]

    Zinc sulfide (ZnS) powders have been obtained by precipitation from homogeneous solutions of various zinc salt compounds with S 2- as precipitating anion, formed by decomposition of thioacetamide. Spherical particles with a very narrow size distribution can be obtained by controlling; the synthesis parameters. The particle sizes are influenced by the nature of the associated anion. For example nanometer-sized ZnS particles are formed using acetate or acetylacetonate anions under acidic pH conditions, controlled by the addition of acetic acid. Although the nucleation is accelerated by the use of acetic acid, limited particle growth occurs because of the formation of complexes with zinc cations that lowers the concentration of free cations in the solution. Also, the complexing-attachment phenomena of the ZnS particles with acetate and acetylacetonate anions lead to the arrest of particle growth processes. The presence of complexed Zn 2+ species in the acidic solution is demonstrated both theoretically, using a model based on the calculations of the solubility isotherms of the soluble species, and by Fourier-transform infrared techniques. The nanostructured ZnS particles may provide a suable semi-conductor nanocluster material for optoelectronic applications as well as a phosphor suitable for application in flat-panel display technology.

  • 215. Valmalette, J. -C
    et al.
    Dutta, Joydeep
    Swiss Federal Inst of Technology, Switzerland.
    Scholz, S. M.
    Hofmann, H.
    Optical properties of gold clusters precipitated on zirconia particles1998In: Materials Research Society Symposium - Proceedings, MRS, Warrendale, United States , 1998, p. 85-88Conference paper (Refereed)
    Abstract [en]

    We have studied precipitation of noble metals with a view to extending these synthetic processes to other metals. In this paper we discuss the synthesis of gold clusters on the surface of oxide fine particles (in the range 60-100 nm). The influence of pH of the solution, the concentration of metal and the reducing agent are discussed. The size distribution of the precipitated gold clusters, determined by transmission electron microscopy, are around 2-10 nm. The interface between the gold clusters and oxide has been investigated by HRTEM. Optical measurements of the zirconia supported gold clusters shows a significant shift in the plasmon resonance. A model based on effective medium theory is proposed taking into account the high refractive index of zirconia.

  • 216. Viphavakit, C.
    et al.
    Themistos, C.
    Komodromos, M.
    Atthi, N.
    Boonrueng, S.
    Mohammed, W. S.
    Dutta, Joydeep
    Sultan Qaboos University, Oman.
    Development of integrated microfluidic device for optical flow rate sensing2013In: Journal of Circuits, Systems and Computers, ISSN 0218-1266, Vol. 22, no 9Article in journal (Refereed)
    Abstract [en]

    The design, fabrication and characterization of an optics based integrated flow rate sensor is presented where the light-fluid interaction is maximized by allowing the liquid and light to propagate along the same direction. The flow rate sensor consists of a 10 mu m deep microchannel placed between two waveguides. The optical waveguides were tapered to fit the channel width, to guide light in and out of the microchannel. A tapering mechanism is proposed to minimize the coupling and propagation losses. The power of the output signal from the designed device was calculate through simulation and it was compared with the actual output signal detected by a fast receiver (higher than 1 MHz). The dynamic change of the light intensity when fluid flows through the channel can also be recorded by this receiver. This scheme allows for a direct measurement of the liquid flow rate with higher interaction length between fluid and light with a dynamic range of up to 0.18. An integrated microfluidic device with high precision and sufficient coupling between the light source and the microfluidic channel is proposed.

  • 217. Viphavakit, Charusluk
    et al.
    Dutta, Joydeep
    Asian Institute of Technology (AIT), Thailand.
    Atthi, N
    Boonruang, S
    Mohammed, Waleed S
    Development of integrated optical characterization bench for sensing microfluidic channel2012Conference paper (Refereed)
    Abstract [en]

    This work introduces design, fabrication and characterization of an optical based integrated flow rate sensor where the light- fluid interaction is maximized by allowing the liquid and light to propagate along the same direction. This is achieved by placing a 10 μm deep channel between two waveguides. The optical waveguides are tapered down to the channel width to feed the light in and out, where tapering is done to minimize the coupling and propagation loss. The output signal is detected by a fast receiver (higher than 1MHz) that records the dynamic change of the light intensity when fluid flows through the channel. The initial results showed a dynamic range of measurement up to 0.18.

  • 218. Vithoonsaritsilp, R.
    et al.
    Lawrence Best, G.
    Dutta, Joydeep
    Asian Institue of Technology, Thailand.
    The impact of slider surface roughness on the touchdown-takeoff hysteresis phenomenon2014In: 5th World Tribology Congress, WTC 2013, Politecnico di Torino (DIMEAS) , 2014, Vol. 3, p. 2481-2484Conference paper (Refereed)
    Abstract [en]

    Summary In this study we looked at the effect of varying the slider roughness from 0.2 to 1.0 nm on slider TD and TO behavior. Varying the roughness in this range has no effect on the TD behavior of the slider, but does effect the TO behavior. Between 0.2 and 0.6 nm roughness, no change in TO behavior was observed. On the other hand, the slider surface with 1.0 nm roughness had a significantly lower TO velocity. We also studied the effect on TO velocity of changing the bonded lubricant ratio from 62 to 70%. The lubricant change had no effect on the TO behavior of the sliders with 1 .Onm roughness, but did increase the TO velocity of the smoother sliders. These two results imply that the slider roughness should not be much below 1 .Onm to assure fast recovery once dynamic instability occurs.

  • 219. Warad, H. C.
    et al.
    Ghosh, S. C.
    Hemtanon, B.
    Thanachayanont, C.
    Dutta, J.
    School of Advanced Technologies, Asian Institute of Technology,Thailand.
    Luminescent nanoparticles of Mn doped ZnS passivated with sodium hexametaphosphate2005In: Science and Technology of Advanced Materials, ISSN 1468-6996, E-ISSN 1878-5514, Vol. 6, no 3-4 SPEC. ISS., p. 296-301Article in journal (Refereed)
    Abstract [en]

    We report the synthesis of luminescent nanoparticles of manganese doped zinc sulfide (ZnS:Mn2+) with an emission peak at around 590 nm. Nanoparticles of ZnS:Mn2+ are prepared by a co-precipitation reaction from homogenous solutions of zinc and manganese salts. Based on Ostwald ripening and surface passivation, we discuss a mechanism for the formation of ZnS:Mn2+ nanoparticles. The reaction proceeds with the nucleation of ZnS crystals, which are immediately passivated by the anions in the solution. This in turn attracts cations including zinc and manganese which contribute to the growth of the crystal. These nanoparticles are sterically stabilized using polyphosphates of sodium namely sodium tripolyphosphate (STTP) and sodium hexametaphosphate (SHMP). The nanoparticles consist of particles of 60-80 nm in diameter, each containing primary crystallites that was estimated from the X-ray diffraction patterns to be at around 2.2 nm

  • 220. Widmer, Christoph
    et al.
    Dutta, Joydeep
    Method for the production of otoplastics and corresponding otoplastic2000Patent (Other (popular science, discussion, etc.))
  • 221.
    Yohai, L.
    et al.
    UNMdP, CONICET, INTEMA, Div Ceram, B7608FDQ, Mar Del Plata, Buenos Aires, Argentina.
    Giraldo Mejía, Hugo
    Procaccini, R.
    Pellice, S.
    Laxman Kunjali, Karthik
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Uheida, Abdusalam
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Nanocomposite functionalized membranes based on silica nanoparticles oss-linked to electrospun nanofibrous support for arsenic(v) sorption from contaminated underground water2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 15, p. 8280-8289Article in journal (Refereed)
    Abstract [en]

    Nanocomposite functionalized membranes were synthesized using surface functionalized mesoporous silica nanoparticles (MCM-NH2 or MCM-PEI) cross-linked to a modified polyacrylonitrile (mPAN) nanofibrous substrate for the removal of 1 mg L-1 of As(V); a concentration much higher than what has been reported for underground water in Argentina. Adsorption studies were carried out in batch mode at pH 8 with nanoparticles in colloidal form, as well as the nanoparticles supported on the modified PAN membranes (mPAN/MCM-NH2 and mPAN/MCM-PEI). Results indicate a twenty-fold improvement in As(V) adsorption with supported nanoparticles (nanocomposite membranes) as opposed to their colloidal form. The adsorption efficiency could be further enhanced by modifying the nanocomposite membrane surface with Fe3+ (mPAN/MCM-NH2-Fe3+ and mPAN/MCM-PEI-Fe3+) which resulted in more than 95% arsenic being removed within the first 15 minutes and a specific arsenic adsorption capacity of 4.61 mg g(-1) and 5.89 mg g(-1) for mPAN/MCM-NH2-Fe3+ and mPAN/MCM-PEI-Fe3+ nanocomposite membranes, respectively. The adsorption characteristics were observed to follow a pseudo-first order behavior. The results suggest that the synthesized materials are excellent for quick and efficient reduction of As(V) concentrations below the WHO guidelines and show promise for future applications.

  • 222. Yusof, H. H. M.
    et al.
    Harun, S. W.
    Dimyati, K.
    Bora, T.
    Sterckx, K.
    Mohammed, W. S.
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Low-Cost Integrated Zinc Oxide Nanorods Based Humidity Sensors for Arduino Platform2019In: IEEE Sensors Journal, ISSN 1530-437X, Vol. 9, no 7, p. 2442-2449Article in journal (Refereed)
    Abstract [en]

    Realization of a simple integrated and low-cost intensity modulation/direct detection-based humidity and vapor detection system utilizing zinc oxide (ZnO) nanorods as the active material is demonstrated. The sensing device comprises of ZnO nanorods optimally grown on a glass substrate and mounted on 3D printed platform for the alignment with a green light-emitting diode setup for an edge excitation. An Arduino platform was used for the signal processing of the detection of the transmitted light. Both forward and backward scattering are affected due to light leakage while propagating through the glass substrate which are further attenuated in the presence of humidity. In this paper, backward scattering was found to be dominant, and thus, with increasing humidity, a reduction in the transmitted light was monitored. When the sensor was tested in a humidity controlled environment, it was found that the output voltage drops by approximately 750 mV upon changing the relative humidity (RH) level from 35% to 90% in a non-linear fashion. The average sensitivity of the sensor was observed to be-12 mV/% throughout the tested RH levels. Sensitivity was found to be higher at-24.6 mV/% for RH's beyond 70%. An average response time of 3.8 s was obtained for RH levels of 85% with respect to the standard ambient humidity conditions (RH 50%), which showed a quicker recovery time of 2.2 s. The proposed sensor device provides numerous advantages, including low-cost production, simplicity in design, ease of use, and stability during handling.

  • 223.
    Yusof, Haziezol Helmi Mohd
    et al.
    Univ Malaya, Dept Elect Engn, Fac Engn, Kuala Lumpur 50603, Malaysia.;Univ Tekn Malaysia Melaka, Fac Elect & Comp Engn, Melaka 76100, Malaysia..
    Harun, Sulaiman Wadi
    Univ Malaya, Dept Elect Engn, Fac Engn, Kuala Lumpur 50603, Malaysia..
    Dimyati, Kaharudin
    Univ Malaya, Dept Elect Engn, Fac Engn, Kuala Lumpur 50603, Malaysia..
    Bora, Tanujjal
    Asian Inst Technol, Sch Engn & Technol, Nanotechnol, Klongluang 12120, Pathumthani, Thailand..
    Mohammed, Waleed S.
    BU, Sch Engn, CROCCS, Pathum Thani 12120, Thailand..
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Optical dynamic range maximization for humidity sensing by controlling growth of zinc oxide nanorods2018In: PHOTONICS AND NANOSTRUCTURES-FUNDAMENTALS AND APPLICATIONS, ISSN 1569-4410, Vol. 30, p. 57-64Article in journal (Refereed)
    Abstract [en]

    An experimental study of the dynamic range maximization with Zinc Oxide (ZnO) nanorods coated glass substrates for humidity and vapor sensing is reported. Growth time of the nanorods and the length of the coated segments were controlled to study the differences between a reference environmental condition (normal humidity or dry condition) and water vapor concentrations. In order to achieve long dynamic range of detection with respect to nanorods coverage, several substrates with triangular patterns of ZnO nanostructures were fabricated by selective hydrothermal growth over different durations of time (5 h, 10 h and 15 h). It was found that maximum dynamic range for the humidity sensing occurs for the combination parameters of normalized length (Z) of 0.23 and normalized scattering coefficient (zeta) of 0.3. A reduction in transmittance by 38% at humidity levels of 80% with reference point as 50% humidity was observed. The results could be correlated to a first order approximation model that assumes uniform growth and the optimum operating conditions for humidity sensing device. This study provides an option to correlate ZnO growth conditions for different vapor sensing applications which can set a platform for compact sensors where modulation of light intensity is followed. rights reserved.

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