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Integration of CCTAO/PDMS composite films into proximity capacitive sensor devices
(2026-12-01)
Bongkarn, Theerachai
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Panpho, Phakakorn
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Charoonsuk, Thitirat
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Vittayakorn, Naratip
;
Pakawanit, Phakkhananan
Flexible capacitive proximity sensors are promising for contactless sensing applications, but their performance is strongly influenced by the dielectric properties and microstructure of the sensing layer. In this work, CaCu<inf>3</inf>Ti<inf>4-x</inf>A<inf>x</inf>O<inf>12</inf>/polydimethylsiloxane (CCTAO/PDMS, A = Nd<sup>3+</sup> or Gd<sup>3+</sup>) composite films were developed as flexible dielectric layers for interdigitated capacitive proximity sensors. Nd- and Gd-doped CCTO ceramics were synthesized by a solid-state reaction method and incorporated into a PDMS matrix at different filler loadings. Structural analysis confirmed that the CCTAO ceramics retained the cubic CCTO phase after rare-earth substitution, while the composite films preserved the characteristic amorphous structure of PDMS with embedded ceramic fillers. The FESEM, EDS mapping and X-ray tomographic microscopy analyses showed that the CCTNdO/PDMS composite had a more uniform distribution of ceramic particles than the CCTO/PDMS system. The dielectric measurements demonstrated the improvement in the dielectric constant of the PDMS-based composites upon CCTNdO incorporation and also indicated that the composites did not exhibit any significant changes in their dielectric properties across the range of frequencies examined. The CCTNdO/PDMS films were found to show the negative capacitance response as a function of distance due to the electric-field shunting mechanism when used in an interdigitated capacitor sensor. The sensor with composition 10 wt% CCTNdO/PDMS had excellent performance with a maximum normalized capacitance change equal to −8.70%, which corresponds to a proximity sensitivity of around 0.42%/mm and an effective sensing range of around 20 mm. It is concluded that the optimization of the loading of the rare-earth material in a flexible PDMS matrix is an effective approach to achieve a compromise between the dielectric enhancement of the sensor and the dispersion of the filler and fringing-field interaction in the contactless capacitive proximity sensor.
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Production of antimicrobial film-reinforced purified cellulose derived from bamboo shoot shell
(2023-06-01)
Manamoongmongkol, Kanjana
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Sriprom, Pongsert
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Phumjan, Lamphung
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Permana, Lasuardi
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Assawasaengrat, Pornsawan
In this paper aimed to enhance the mechanical properties of an antimicrobial film by incorporating purified cellulose obtained from bamboo shoot shells into a chitosan matrix. Films with varying amounts of cellulose (0%w/v, 0.2%w/v, and 0.4%w/v) were investigated. Results indicated that the chitosan film reinforced 0.4%w/v cellulose exhibited higher tensile strength (43.50 MPa) and elongation at break (39.40 %) compared to the film without cellulose (34.47 MPa, 18.27 %). Additionally, the film with 0.4%w/v cellulose showed antimicrobial activity against B. cereus (MIC 12.5 mg/mL), S. aureus (MIC 6.25 mg/mL), E. coli (MIC 6.25 mg/mL), and exhibited 68.67 % inhibition of Fusarium oxysporum. Due to its biodegradability, favorable mechanical properties, and strong antimicrobial ability, the cellulose-chitosan film presents a promising alternative to be applied in the food industry, such as in packaging of dried food or as a coating film.
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Synthesis and preparation of bacterial cellulose/calcium hydrogen phosphate composite film for mulching film application
(2021-01-01)
Pinpru, Nattapong
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Charoonsuk, Thitirat
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Khaisaat, Supharada
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Sawanakarn, Oubonwan
;
Vittayakorn, Naratip
This research aims to prepare mulching film from starting substrate of Acetobacter xylinum in bacterial cellulose (BC). BC was extracted from rotten coconut fruit. At the same time, CaHPO4 fertilizer was prepared from waste cockle shell. Both BC and CaHPO4 were analyzed by XRD and SEM for investigation of crystal structure and morphology. The results reveal well specific characterization of BC and CaHPO4. The BC and CaHPO4 composite film were further forming by solvent casting method. It was found that the increasing amount of CaHPO4 to 3 and 5%w/w were dramatically increased the percent of water absorption and rate of biodegradation, but it must sacrifice to mechanical properties. The morphology results were also disclosure that the higher amount of CaHPO4 (3 and 5 %w/w) composite film obviously caused phase separation that was correspondent to lower in mechanical properties. Thus, BC/1%CaHPO4 composite film was selected for mulching film because of good mechanical properties and gradually slow degradation.
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Anatase/Rutile TiO2 composite thin films prepared via dip coating technique and their hydrophilicity, stability and photocatalytic activity
(2018-01-01)
Ibrahim, Ammar
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Phoohinkong, Weerachon
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Mekprasart, Wanichaya
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Pecharapa, Wisanu
In this work, titanium dioxide (TiO<inf>2</inf>) mixed-phase powders were prepared by sonochemical process in combination with calcination at different temperature in range of 400C to 1000C. The as-prepared powders were dispersed with tetraethyl orthosilicate (TEOS) as supported matrix of TiO<inf>2</inf> for homogeneous colloid and used as starting precursor for thin film coating. The designated thin films were deposited onto glass substrates by dip coating process. X-ray diffraction technique was employed to evaluate TiO<inf>2</inf> phase ratio meanwhile the film morphologies and hydrophilicity were investigated using scanning electron microscope and water contact angle, respectively. UV-Vis spectrophotometer was used to analyse the photcatalytic properties of the films. Photocatalytic activity of the prepared film was performed by mean of the decolorization of Rhodamine B dye solution under solar irradiation. The photocatalytic performance of assigned films was investigated and correlated mechanisms responsible for the activity are discussed.
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