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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
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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 = Nd3+ or Gd3+) 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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Synergistic Enhancement of Mechanical and Dielectric Properties in BaTiO3/PDMS Composites for Flexible Energy Harvesting Devices
(2026-01-01)
Rerngroen, Nakulkarn
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Sasipongpan, Apinya
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Vittayakorn, Wanwilai
This study presents the fabrication, characterization, and performance evaluation of flexible piezoelectric composites based on polydimethylsiloxane embedded with varying volume fractions (0–25 vol%) of barium titanate nanoparticles. The composites were prepared via a conventional casting method and systematically analyzed to investigate the synergistic enhancement of their mechanical, dielectric, and piezoelectric properties. Structural and morphological analyses confirmed the retention of the crystalline BaTiO<inf>3</inf> phase and its uniform dispersion within the PDMS matrix, with some agglomeration observed at higher filler loadings. Mechanical testing revealed that the 20 vol% BaTiO<inf>3</inf> composite exhibited optimal tensile strength and flexibility. Dielectric measurements showed significant increase in the dielectric constant with increasing BaTiO<inf>3</inf> content, with the 25 vol% composite achieving a 100% enhancement compared to pure PDMS. Theoretical modeling was employed to compare experimental results with established effective medium theories. Under cyclic compression, the composites demonstrated a progressive increase in output voltage, reaching up to ~426 V at 25 vol% BaTiO<inf>3</inf>, surpassing performance reported in previous studies. Additionally, the incorporation of carbon nanotubes further enhanced dielectric efficiency and mechanical stretchability, although a slight reduction in piezoelectric output was observed. These results underscore the potential of BaTiO<inf>3</inf>/PDMS nanocomposites, with and without CNTs, for next-generation flexible energy harvesting devices.
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High-performance triboelectric and piezoelectric nanogenerator enabled by BF-BT-NZN multifunctional ceramic filler
(2025-10-01)
Sumang, Rattiphorn
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Jantaratana, Pongsakorn
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Charoonsuk, Thitirat
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Vittayakorn, Naratip
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Bongkarn, Theerachai
The development of efficient and flexible energy-harvesting materials is essential for advancing self-powered electronic devices. In this study, we report the fabrication of flexible composite films by incorporating (1-x)(0.75BiFeO<inf>3</inf>-0.25BaTiO<inf>3</inf>)-xNd(Zn<inf>0.67</inf>Nb<inf>0.33</inf>)O<inf>3</inf>,abbreviated as (BF-BT-NZN), ceramic powder into a PDMS matrix, with filler contents ranging from 5 to 25 wt%. The optimized 10 wt% composite film demonstrated a maximum output voltage of 112.24 V and a current of 5.69 µA approximately 11 and 18 times higher than pure PDMS, respectively. Following a poling treatment, the output further increased to 149.54 V and 10.71 µA. The film exhibited excellent flexibility and durability, enabling practical applications such as powering LEDs, a digital watch, and charging capacitors. These results highlight the potential of BF-BT-NZN/PDMS composites as high-performance materials for wearable energy-harvesting applications.
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High-performance flexible lead-free piezo-antiferroelectric based on NaNbO3/PDMS composites for energy harvesting application
(2024-12-01)
Sumang, Rattiphorn
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Charoonsuk, Thitirat
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Vittayakorn, Naratip
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Panpho, Phakakorn
To bring the rapidly advancing technology of energy harvesters into commercial use, further development is required for devices that can enhance output performance, flexibility, ease of fabrication, and low cost. A hybrid concept is a promising method. It combines between the piezoelectric nanogenerator (PENG) and the triboelectric nanogenerator (TENG) to provide a high-performance nanogenerator. This study introduced a high-performance hybrid PENG and TENG device that operates using a NN-BNT/PDMS composite film. The NN-BNT/PDMS composite based nanogenerators were fabricated with varying NN-BNT content. Then, dielectric test and electrical properties were investigated. Adding NN-BNT into the PDMS composite film resulted in a higher dielectric constant compared to pure PDMS, leading to increase of electrical output. Under the optimal condition of a 3 wt%. NN-BNT composite based hybrid nanogenerator, the electrical output was significantly enhanced, reaching 40 V, 0.95 μA/cm2, and 200 μW/cm2 compared to pure PDMS. This nanogenerator further used to the charging of a capacitor to a voltage of around 1 V within 5 s and also powered multiple LEDs. The successful development of this highly efficient NN-BNT/PDMS composite film-based hybrid concept sheds light on energy harvesting devices.
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Flexible hybrid piezo/triboelectric energy harvester based on a lead-free BNT-BT-KNN ceramic-polymer composite film
(2024-12-01)
Panpho, Phakakorn
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Charoonsuk, Thitirat
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Vittayakorn, Naratip
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Bongkarn, Theerachai
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Sumang, Rattiphorn
Environment-friendly piezoelectric micro/nanogenerators have attracted tremendous attention due to the increasing demand for portable self-power devices. Here, the [(0.94−x)Bi<inf>0.5</inf>Na<inf>0.5</inf>TiO<inf>3</inf>–0.06BaTiO<inf>3</inf>–xK<inf>0.5</inf>Na<inf>0.5</inf>NbO<inf>3</inf>; BNT-BT-xKNN] lead-free ceramic, at x = 0, 0.02, 0.04, 0.06, 0.08 and 0.10 mol%, was prepared via the solid-state method. The doping concentration x = 0.02 mol% shows the highest dielectric properties and the lowest dielectric loss. The active layer of the hybrid device is made by mixing BNT-BT-2KNN into the PDMS to form a series of polymer-ceramic composite films ranging from 7 to 19 wt% of BNT-BT-2KNN. The electrical response of the composite film is systematically studied with the addition of different weight percentages of the particles to the PDMS matrix. It was found that incorporating BNT-BT-2KNN at 11 wt% into the PDMS matrix exhibited the optimum harvesting performance, resulting in an output voltage and current density of about 30 V and 0.28 μA/cm2, respectively. The hybridized PENG and TENG devices could operate in a long-term cyclic mode, charge the capacitor for energy storage, and also light up LEDs. This research proposed a simple device fabrication and provided a guideline for the development of high-performance microgenerators, which is crucial for device development and practical use in the future.
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Enhancement of Bacterial Anti−Adhesion Properties on Robust PDMS Micro−Structure Using a Simple Flame Treatment Method
(2022-02-01)
Houngkamhang, Nongluck
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Chaisawat, Ploymanee
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Joksathit, Waisaree
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Samart, Sutichai
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Chutipaijit, Sutee
Biofilm−associated infections caused by an accumulation of micro−organisms and pathogens significantly impact the environment, health risks, and the global economy. Currently, a non−biocide−releasing superhydrophobic surface is a potential solution for antibacterial purposes. This research demonstrated a well−designed robust polydimethylsiloxane (PDMS) micro−structure and a flame treatment process with improved hydrophobicity and bacterial anti−adhesion proper-ties. After the flame treatment at 700 ± 20 °C for 15 s, unique flower−petal re−entrant nano−structures were formed on pillars (PIL−F, width: 1.87 ± 0.30 μm, height: 7.76 ± 0.13 μm, aspect ratio (A.R.): 4.14) and circular rings with eight stripe supporters (C−RESS−F, width: 0.50 ± 0.04 μm, height: 3.55 ± 0.11 μm, A.R.: 7.10) PDMS micro−patterns. The water contact angle (WCA) and ethylene glycol contact angle (EGCA) of flame−treated flat−PDMS (FLT−F), PIL–F, and C–RESS−F patterns were (133.9 ± 3.8°, 128.6 ± 5.3°), (156.1 ± 1.5°, 151.5 ± 2.1°), and (146.3 ± 3.5°, 150.7 ± 1.8°), respectively. The Escherichia coli adhesion on the C−RESS−F micro−pattern with hydrophobicity and superoleophobicity was 42.6%, 31.8%, and 2.9% less than FLT−F, PIL−F, and Teflon surfaces. Therefore, the flame−treated C−RESS−F pattern is one of the promising bacterial anti−adhesion micro−structures in practical utilization for various applications.

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