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Author: search.filters.author.Chaisriratanakul, WoraphanHas files: No

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    Sensing layer combination of vertically aligned ZnO nanorods and graphene oxide for ultrahigh sensitivity IDE capacitive humidity sensor
    (2020-06-01)
    Pongampai, Satana
    ;
    Pengpad, Puttapon
    ;
    Meananeatra, Rattanawan
    ;
    Chaisriratanakul, Woraphan
    ;
    Poyai, Amporn
    An interdigitated electrode (IDE) capacitive humidity sensor fabricated on a silicon substrate was used to investigate sensing materials, which proved to be an ultrahigh-sensitivity humidity sensor. A sensing layer combination (SLC) between vertically aligned ZnO nanorods and optimal graphene oxide (GO) was prepared on the device and was tested as a humidity sensor. X-ray diffractometry (XRD) exhibited crystallized wurtzite structure of ZnO nanorods and transmission electron microscope (TEM) shown perfectly indexed hexagonal wurtzite ZnO structure dots position correspondence. A scanning electron microscope (SEM) was used to analyze ZnO nanorods/GO morphologies. Furthermore, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) clearly exhibited GO presence and hydrophilic functional groups (carboxyl, epoxy, and hydroxyl), respectively. The SLC prominently demonstrated ultrahigh sensitivity (up to 196.95% or 1.97 times from commercial sensor; HS1101, Humirel) and linear responses behavior with 0.96 for coefficient of determination. The device sensitivity obviously improved as steps of 40, 50, 60, 70, 80, and 90% RH at values of 1.09, 1.41, 1.51, 1.65, 1.80, and 1.91 times, respectively. The device also exhibited fast response (25 s) and short recovery times (17 s). Its hysteresis (6.58%) manifestly improved to 1.84 times. Moreover, repeatability and long-term ability of the device demonstrated high accuracy (range ±0.37pF) and durability. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
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    Effect of amino-, mercapto-silane coupling as a molecular bridge of polyvinyl chloride ion-selective membrane on silicon nitride for nitrate ISFET sensors
    (2020-06-01)
    Chaisriratanakul, Woraphan
    ;
    Bunjongpru, Win
    ;
    Pankiew, Apirak
    ;
    Srisuwan, Awirut
    ;
    Jeamsaksiri, Wutthinan
    This paper presents a modification of a Si<inf>3</inf>N<inf>4</inf> Polyvinyl chloride (PVC) membrane on a surface of an ion selective field effect transistor (ISFET) using silane with two different functional groups for comparison of nitrate sensing characteristics. Effects of amino (NH<inf>2</inf>) and thiol groups (SH) toward structures and characteristics of nitrate sensors were analyzed using the following techniques: ellipsometry, scanning electron microscope (SEM), infrared spectroscopy (FTIR), zeta potential and electrochemical impedance spectroscopy (EIS). After surface modification, the thickness of the silane layers for both cases were similar with uniform surface topology. Absolute zeta potentials of PVC ion-selective membrane (7.65 mV) and Si<inf>3</inf>N<inf>4</inf> surface modification with MPTMS (-51.46 mV) reflected the surface functional group and showed that membranes could be bonded to the PVC ion-selective membrane. Since APTMS produced higher EIS than MPTMS, the resulting nitrate sensors modified by MPTMS had higher sensitivity than the sensors with APTMS. Finally, the modified sensors had a useful life time of 3 months.
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    Ultrahigh sensitivity and linearity humidity sensor base on vertical alignment of ZnO nanorods sensing layer
    (2019-03-01)
    Pongampai, Satana
    ;
    Pengpad, Puttapon
    ;
    Meananeatra, Rattanawan
    ;
    Horprathum, Mati
    ;
    Chaisriratanakul, Woraphan
    Capacitive humidity sensor was fabricated on CMOS technology with multiple parallel metals coplanar (interdigitage electrodes, IDEs) by lithography process base on silicon bulk substrate and coated Nickel-gold onto IDEs by electroless method. This paper proposed the IDEs humidity sensor with vertical alignment of zinc oxide (ZnO) nanorods on thick seed layer by sputtering process (IDEs/ZnO nanorods) for high sensitivity. ZnO nanorods structure and morphology were obtained by scanning electron microscope (SEM) and X-Ray diffractometer (XRD), respectively. The humidity sensors were comparatively examined properties before/after sputtering process. We have observed sputtering time for 3.0h with 100 nm thick seed layer effected to optimal vertical alignment of ZnO nanorods (length 480 nm) which shown high sensitivity (up to 1913.83%). Moreover, the IDEs/ZnO nanorods significantly improved on wide ranges relative humidity (30-90 %RH), fast response (up to 42.39%) and a little recovery times (16sec), precise repeatability as well as low hysteresis (18.22%). Finally, it demonstrated long-term stability and also exhibited a temperature dependence.
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    Ultrahigh linear sensitivity of capacitive humidity sensor base on bilayer structure of graphene oxide
    (2019-03-01)
    Pongampai, Satana
    ;
    Pengpad, Puttapon
    ;
    Meananeatra, Rattanawan
    ;
    Chaisriratanakul, Woraphan
    ;
    Thitirungraung, Wisut
    Capacitive humidity sensor is designed on interdigitage electrodes (IDEs) by lithography process for nice humidity absorption and desorption. This paper proposed the IDEs humidity sensor base on bilayers sensing of graphene oxide (GO) structure by dip coating method. Each GO layer is held by covalent-bond forces from adhesive layer. It demonstrates durable of sensing layer material. Raman spectroscopy analysis is exhibited on GO presence and scanning electron microscope (SEM) explored on the GO bilayers structure. The IDEs/GO bilayers humidity sensor demonstrated ultrahigh sensitivity (up to 2014.61%) and linear responses at relative humidity (RH) ranges 10 to 70% while IDEs/GO single layer showed exponential responses. Moreover, it significantly improved on response (12 sec) and recovery times (18sec), a little hysteresis (up to 46.77%) and stable repeatability. Finally, the durable of IDEs/GO bilayers humidity sensor is exhibited by long-term ability measurement (time period 35 days). Therefore, these characteristics of GO bilayers structure base on adhesive layer are clearly demonstrated high performances for alternatively used with humidity sensor applications.
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    Influence of graphene oxide concentration on IDES capacitive humidity sensor response behavior
    (2019-01-01)
    Pongampai, Satana
    ;
    Pengpad, Puttapon
    ;
    Meananeatra, Rattanawan
    ;
    Chaisriratanakul, Woraphan
    ;
    Thitirungraung, Wisut
    —Capacitive type humidity sensor was fabricated on CMOS technology by lithography process base on silicon p-substrate with Nitride passivation layer and designed on interdigitage electrodes (IDEs). This paper proposed the influence of various stock graphene oxide (GO) concentrations on humidity sensor responses behavior by drop coating method. The Raman spectroscopy is demonstrated for GO presence and scanning electron microscope (SEM) is exhibited the GO surface morphologies. The capacitance value is examined under different relative humidity (RH) ranges at 0.30% to 80% RH. The IDEs capacitive humidity sensor shows linear, polynomial and exponential responses behaviors for high, medium and low stock GO concentrations, respectively. The high stock GO concentration is significantly improved all dominant humidity sensor properties, especially the sensitivity at low RH (10%, 20%, 30% and 40% RH) which is improved up to 6683.65%, 2097.27%, 1984.91% and 1465.93%, respectively. Furthermore, it shows linear responses behavior by 0.991 for coefficient of determination of wide RH. Moreover, the IDEs capacitive humidity sensors are comparatively examined response/recovery times, hysteresis as well as repeatability. Finally, high stock GO concentration of humidity sensor is exhibited under various temperature operating ranges (20-50 degree Celsius). It clearly demonstrates for alternative applicability to use on humidity sensor applications.
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    High sensitive nanocrystal titanium nitride EG-FET pH sensor
    (2013-10-29)
    Rayanasukha, Yossawat
    ;
    Porntheeraphat, Supanit
    ;
    Bunjongpru, Win
    ;
    Khemasiri, Narathon
    ;
    Pankiew, Apirak
    Solid state pH-sensor device with high efficiency has successfully prepared by using TiN thin film as sensing membrane of extended gate field effect transistor (EG-FET) device. This research has described the physical properties and sensing characteristics of TiN membrane thin film which deposited on SiO<inf>2</inf>/Si substrate through reactive D.C. magnetron sputtering system. Thenanocrytal-TiNwith anatasestructure depended on substrate heating conditions was revealed from glancing angle x-ray diffraction. The I<inf>DS</inf>-V<inf>GS</inf> measurement in the standard buffer solutions showed that the sensitivity of fabricated TiN-EGFET pH deviceis 59.82mV/pH. © (2013) Trans Tech Publications, Switzerland.