Humidity sensors based on silica nanoparticle aerogel thin films

Wang, Chien-Tsung; Wu, Chun-Lung; Chen, I-Cherng; Huang, Yi-Hsiao

doi:10.1016/j.snb.2004.10.034

Cited by 126 publications

(68 citation statements)

References 22 publications

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“…The C -value increased from 3.2183 × 10 −11 F to 9.9741 × 10 −10 F with a “ S ” of ~3000% at the signal frequency of 10 2 Hz but when the test frequency is 10 5 Hz, the capacitance varied from 1.2832 × 10 −11 to 2.8174 × 10 −11 F with “ S ” of ~120% across the RH range of 33%–95%, respectively. The sensitivity of our developed sensor is higher than that of some other ceramic based humidity sensors reported elsewhere (for example, ~2900% for porous ZnAl 2 O 4 spinel nanorod, 85% for silica nanoparticles aerogel thin films, ~966% for SiC nanowires, ~800% for thermally carbonized porous silicon, ~500% for alumina nanowire, 1490% for (PEPC + NiPc + Cu 2 O) and so on based humidity sensors) [16,56,57,58,59,60]. Therefore, in our further study the 10 2 Hz would be considered as best test frequency for the analysis of sensor characteristics.…”

Section: Resultsmentioning

confidence: 74%

Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

Tripathy

Pramanik

Manna

et al. 2016

Sensors

116

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Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO)-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s) and recovery (34.27 s), and very low hysteresis (3.2%) in a 33%–95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors.

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Section: Resultsmentioning

confidence: 74%

Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

Tripathy

Pramanik

Manna

et al. 2016

Sensors

116

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“…Therefore, only S1050/PDMS composite could be used to develop a flexible composite film with potentially the best in performance. The capacitance values of the S1050 ceramic and S1050/PDMS composite film were in the order of 10 −10 F and 10 −11 F, respectively, which closely resembled those of different nanoparticles and composites [50,51]. The capacitance value of the S1050/PDMS composite film is significantly higher than the other titanate fibrous materials [51].…”

Section: Resultsmentioning

confidence: 98%

Synthesis and Characterizations of Novel Ca-Mg-Ti-Fe-Oxides Based Ceramic Nanocrystals and Flexible Film of Polydimethylsiloxane Composite with Improved Mechanical and Dielectric Properties for Sensors

Tripathy

Pramanik

Manna

et al. 2016

Sensors

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Armalcolite, a rare ceramic mineral and normally found in the lunar earth, was synthesized by solid-state step-sintering. The in situ phase-changed novel ceramic nanocrystals of Ca-Mg-Ti-Fe based oxide (CMTFOx), their chemical reactions and bonding with polydimethylsiloxane (PDMS) were determined by X-ray diffraction, infrared spectroscopy, and microscopy. Water absorption of all the CMTFOx was high. The lower dielectric loss tangent value (0.155 at 1 MHz) was obtained for the ceramic sintered at 1050 °C (S1050) and it became lowest for the S1050/PDMS nanocomposite (0.002 at 1 MHz) film, which was made by spin coating at 3000 rpm. The excellent flexibility (static modulus ≈ 0.27 MPa and elongation > 90%), viscoelastic property (tanδ = E″/E′: 0.225) and glass transition temperature (Tg: −58.5 °C) were obtained for S1050/PDMS film. Parallel-plate capacitive and flexible resistive humidity sensors have been developed successfully. The best sensing performance of the present S1050 (3000%) and its flexible S1050/PDMS composite film (306%) based humidity sensors was found to be at 100 Hz, better than conventional materials.

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“…In humidity sensing, silicon-based materials contribute good response towards humidity measurement [4]. Chien-Tsung et al found that porous silica substrate gives better humidity sensing properties as better trapping of polar type water molecules is achievable with large number of pores on surface [5]. El Kamel et al states that Ptbased substrates are suitable for deposition of perovskite materials such as BaTiO 3 due to its high electron affinity and allowable for high temperature process [6].…”

Section: Introductionmentioning

confidence: 99%

Substrate effect on structural and humidity sensing of sol-gel derived Er-BaTiO3 thin films

Saif¹,

Ooi²,

Teh³

2017

AIP Conference Proceedings

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Abstract. Sol-gel erbium doped barium titanate (Er-BaTiO 3 ) thin films have been coated on SiO 2 /Si, fused silica, and Pt/Ti/SiO 2 /Si substrates. The crystallinity and phase of the thin films have been identified using X-ray diffractometer (XRD). The effect of substrate type on the surface morphologies of the films has been investigated using atomic force microscope (AFM). The influence of humidity on the electrical properties of Er-BaTiO 3 films has been carried out using semiconductor parameter analyzer (SPA). XRD patterns show that the films are crystallized with perovskite structure. AFM microimages show well-distributed grains, dense and crack-free surface for the films. The film fabricated on fused silica substrate gives the smoothest surface with smallest grain size, whereas the film coated on Pt/Ti/SiO 2 /Si gives a relatively rough surface with the largest grain size among the other substrates. The resistance values of the Er-BaTiO 3 films at different humidity percentages show that a decrement trend with the humidity percentage and the coated film on SiO 2 /Si substrate has the lowest resistance values compared with the films on other substrates, indicating that SiO 2 /Si substrate gives the best conduction and it could be a good candidate for humidity sensor for such type of material.

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Humidity sensors based on silica nanoparticle aerogel thin films

Cited by 126 publications

References 22 publications

Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

Synthesis and Characterizations of Novel Ca-Mg-Ti-Fe-Oxides Based Ceramic Nanocrystals and Flexible Film of Polydimethylsiloxane Composite with Improved Mechanical and Dielectric Properties for Sensors

Substrate effect on structural and humidity sensing of sol-gel derived Er-BaTiO3 thin films

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