KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 10 of 75

Some of the metrics are blocked by your
consent settings
Unveiling unusual coloration in amorphous phosphate pigments: a study inspired by the mineral Brazilianite
(2026-12-01)
Onoda, Hiroaki
;
Higuchi, Kanata
;
Charoonsuk, Thitirat
;
Pulphol, Phieraya
;
Muanglhua, Rangson
Brazilianite, with the formula NaAl<inf>3</inf>(PO<inf>4</inf>)<inf>2</inf>(OH)<inf>4</inf>, exhibits an intriguing pale yellow to green coloration, a phenomenon not readily explained by the absence of conventional d-block chromophoric metal ions. This study investigates the synthesis of amorphous phosphate-based pigments compositionally analogous to Brazilianite, aiming to replicate and understand the origin of its distinctive coloration through controlled precursor stoichiometry and thermal processing. Sodium, aluminum, and phosphate precursors were precisely mixed and thermally treated. X-ray diffraction (XRD) confirmed the predominantly amorphous nature of the synthesized materials, irrespective of achieving long-range crystalline order analogous to mineral Brazilianite. Despite this, samples processed at intermediate temperatures (e.g., 300–400 °C) exhibited a consistent yellowish hue. This non-conventional coloration, attributed to intrinsic electronic or structural features within the amorphous phosphate network rather than traditional chromophores, represents a significant scientific innovation. This coloration was found to be intrinsically linked to the phosphate network itself. Stability assessments in acidic (0.1 wt% H<inf>2</inf>SO<inf>4</inf>) and basic (0.1 wt% NaOH) environments revealed significant vulnerability, attributed to the facile dissolution of sodium and aluminum phosphate species. Notably, the yellowish coloration persisted across various Na/Al/P compositional ratios, even with systematic variations in aluminum or sodium content. This strongly suggests that the observed color is not critically dependent on a precise Na: Al stoichiometry but is fundamentally governed by the local electronic structure within the phosphate network, potentially involving defect centers or specific P-O-Al/Na linkages. These findings offer valuable insights into designing novel, non-toxic, color-stable pigments where coloration arises from mechanisms beyond traditional transition metal ion incorporation, highlighting the potential role of controlled disorder in phosphate-based materials for sustainable applications.
Some of the metrics are blocked by your
consent settings
Upcycling waste mycelium into chitosan-based biodegradable triboelectric nanogenerators with enhanced energy output
(2026-12-01)
Panpho, Phakakorn
;
Charoonsuk, Thitirat
;
Pakawanit, Phakkhananan
;
Bongkarn, Theerachai
;
Vitayakorn, Narathip
Sustainable nanogenerators require bio-based active layers that combine interfacial polarization, mechanical deformability, and stable charge generation. Herein, waste mushroom mycelium (WMM) was upcycled as a multifunctional biofiller in chitosan (CTS)-based films for piezoelectric/triboelectric energy-harvesting devices. By controlling WMM loading and glycerol plasticization, this study reveals a morphology–dielectric–compliance coupling mechanism governing device performance. FTIR, XRD, SEM, and X-ray tomographic analyses show that WMM modifies hydrogen bonding, chain packing, surface texture, and internal filler connectivity, while excessive loading causes aggregation and structural non-uniformity. The optimized 7 wt% WMM/CTS film produced a PENG-mode output of 1.87 V and 1.72 μA and a TENG output of 15.39 V and 2.54 μA. The output of the TENG was further improved to 20.35 V and 2.80 μA at a maximum power of about 44 μW with glycerol plasticization. Capacitor charging, cyclic operation, LED array illumination and seven-segment display were also shown with the optimized device. Notably, the highest low-frequency apparent permittivity was observed at 11 wt% WMM/CTS, but its output decreased because of aggregation, dielectric loss, and mechanical non-uniformity. These results demonstrate that optimum energy harvesting is governed not by dielectric permittivity alone but by balanced polar interfaces, surface asperity, moderate dielectric loss, and contact compliance. This work establishes waste mycelium as a functional biofiller for sustainable biopolymer active layers in low-power self-powered systems.
Some of the metrics are blocked by your
consent settings
Integration of CCTAO/PDMS composite films into proximity capacitive sensor devices
(2026-12-01)
Bongkarn, Theerachai
;
Panpho, Phakakorn
;
Charoonsuk, Thitirat
;
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 = 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.
Some of the metrics are blocked by your
consent settings
Kinetic analysis of liquid–solid contact electrification: Using adsorption models as mechanistic probes for hybrid EDL behavior
(2026-08-01)
Chaithaweep, Kanokwan
;
Pharino, Utchawadee
;
Pongampai, Satana
;
Sriphan, Saichon
;
Charoonsuk, Thitirat
Liquid–solid interfaces are central to technologies ranging from energy storage to triboelectric nanogenerators (TENGs). Whereas classical electric double layer (EDL) theory describes these interfaces mainly in terms of electrostatic ion adsorption, hybrid EDL concepts suggest that interfacial electron transfer may also contribute importantly to charge generation. However, the hybrid EDL model has so far been discussed primarily at a qualitative level or through complex theoretical and computational treatments, and a simple, experimentally accessible macroscopic kinetic handle that can discriminate, in operando, between adsorption‑dominated and ET‑influenced regimes remains lacking. By analyzing high-resolution charging dynamics over systematically varied H₂SO₄ and HNO₃ concentrations, a clear concentration-dependent kinetic transition is identified. At low ionic strengths, the charging process is described more effectively by pseudo-second-order (PSO) kinetics, consistent with a reaction-influenced interfacial step, whereas at higher concentrations the system becomes pseudo-first-order (PFO) dominated, consistent with transport- and ion-screening-controlled behavior. Although previous studies have provided compelling theoretical and spectroscopic evidence that interfacial electron transfer contributes to liquid–solid contact electrification in TENGs, these mechanisms have rarely been examined through such simple macroscopic kinetic formalisms. In this work, classical adsorption kinetic models are used as operational probes for distinguishing electron-transfer-influenced regimes from ion-transport-dominated regimes at PTFE/liquid interfaces. The PSO-to-PFO crossover reported here is interpreted within the hybrid EDL framework as a kinetic marker of a transition from an electron-transfer-influenced charging regime at low concentration to an ion-transport- and screening-dominated regime at high concentration, thereby demonstrating how adsorption kinetics can serve as a practical diagnostic language for liquid–solid triboelectric systems.
Some of the metrics are blocked by your
consent settings
Interfacial field-driven self-poling in a lead-free P(VDF–TrFE)/BCZT nanogenerator: achieving high-performance energy harvesting via percolation-optimized dielectric coupling
(2026-07-23)
Ukasi, Sirinya
;
Triputtikun, Jakkrit
;
Sae-tang, Chanachot
;
Sumang, Rattiphorn
;
Panpho, Phakakorn
Achieving spontaneous dipole alignment without external poling remains a grand challenge in developing high-performance ferroelectric nanogenerators. This work reports a self-poling mechanism driven by engineered interfacial fields at the polymer–ceramic junction. By embedding lead-free Ba<inf>0.85</inf>Ca<inf>0.15</inf>Zr<inf>0.1</inf>Ti<inf>0.9</inf>O<inf>3</inf> (BCZT) crystals into a P(VDF–TrFE) matrix, we create strong localized electric fields that promote unidirectional dipole orientation, thereby eliminating the need for conventional electrical poling procedures. The resulting hybrid piezo-triboelectric nanogenerator (H-PTENG), optimized at a 1 wt% BCZT loading, exhibits remarkable energy-harvesting performance with a high open-circuit voltage (∼173.4 V), short-circuit current (∼5.23 µA), and power density (∼182 µW cm−2), outperforming most lead-free counterparts. This dielectric percolation-like optimum maximizes the dielectric–ferroelectric coupling mediated by Maxwell–Wagner–Sillars interfacial polarization, simultaneously enhancing piezoelectric and triboelectric outputs while preserving low dielectric loss. The device also demonstrates robust mechanical durability (>10 000 bending cycles) and retains usable output under varying humidity and temperature conditions, although its performance is reduced at ultra-high relative humidity due to water-induced charge dissipation. Its real-world applicability is confirmed by directly powering commercial electronics, including 82 LEDs, a digital wristwatch, an electronic scoreboard, and a Bluetooth-enabled humidity–temperature sensor. Collectively, this work establishes a scalable, lead-free, and poling-free design paradigm based on interfacial field engineering for next-generation flexible, self-powered electronic systems.
Some of the metrics are blocked by your
consent settings
The Y3+ Donor-Doped CCTO (Ca0.95Y0.05Cu3Ti4O12) Dielectric Fillers for Electrical Output Enhancement of Flexible Triboelectric Nanogenerator
(2026-06-03)
Saichompoo, Kittipan
;
Rattanawongwiboon, Thitirat
;
Kingkam, Wilasinee
;
Pakawanit, Phakkhananan
;
Sukkha, Usa
The escalating wearable electronic devices with their flexible energy sources demand has rendered the imperative scientific challenge on the development of materials for the flexible triboelectric nanogenerators (F-TENG), one of advanced energy harvesting systems. Dielectric material optimization, the Y3+ donor-doped calcium copper titanate based on exactly stoichiometric Ca<inf>0.95</inf>Y<inf>0.05</inf>Cu<inf>3</inf>Ti<inf>4</inf>O<inf>12</inf> (CCTYO), serves as a critical pathway in this work for achieving enhanced F-TENG via compositing with the polydimethylsiloxane (PDMS) polymer. The enhancement of electrical output has garnered substantial interest owing to its increased relative permittivity ((Formula presented.)). The influence of the loaded CCTYO amounts on structure, morphologies, dielectric properties, and electrical output, including open-circuit voltage (V<inf>OC</inf>), short-circuit current (I<inf>SC</inf>) and power density for PDMS/CCTYO composites is investigated. As compared with loading undoped CCTO, the additional Y3+ can improve higher F-TENG output by increasing the (Formula presented.) along with maintaining the loss tangent (tan δ < 0.02) at optimized condition. The appropriate amounts of CCTYO 0.75 wt% make the PDMS/CCTYO F-TENG to achieve V<inf>OC</inf> of ∼76.4 V (8.5 V/cm2) and I<inf>SC</inf> of ∼130.0 μA (14.4 μA/cm2), which were higher than pristine PDMS for 2.7 and 4.3 times. The power density of 53 µW/cm2 is 8.9 times higher than that of 6.3 µW/cm2 from the pristine PDMS. This study also provides a COMSOL multiphysics simulation, bridging laboratory experiments, for quantifying the triboelectric capability of dielectric materials.
Some of the metrics are blocked by your
consent settings
Harvesting energy from friction: the revolutionary decade of triboelectric nanogenerators
(2026-04-01)
Khanapurarm, Uday Kumar
;
Rani, Gokana Mohana
;
Panda, Swati
;
Charoonsuk, Thitirat
;
Mistewicz, Krystian
Triboelectric nanogenerators (TENGs) have rapidly developed into a transformative energy harvesting technology, enabling self-powered, sustainable electronic systems. This review offers the first comprehensive, multidisciplinary perspective that connects the physics of triboelectric charge transfer with material innovation, device engineering, and real-world applications. We systematically categorize and measure the triboelectric series across a wide range of materials, including polymers, 2D materials, MOFs, perovskites, cellulose, and biodegradable frameworks, using experimentally validated methods. In addition to traditional approaches, this work highlights emerging strategies such as machine learning-guided material discovery, 3D printing, and advanced structural engineering to improve charge retention, durability, and power output. Unlike existing reviews, it uniquely combines theory and application insights, presents diverse uses from biomedical sensing and environmental monitoring to underwater communication and mechanoluminescence, and outlines a forward-looking plan for sustainable energy harvesting. This comprehensive synthesis serves as an essential resource for researchers and technologists designing next-generation TENGs and multifunctional self-powered devices.
Some of the metrics are blocked by your
consent settings
An architected silk fibroin-lignin multilayer with deep-level trapping states for high-output triboelectric nanogenerators
(2026-03-01)
Suktep, Natdanai
;
Sae-tang, Chanachot
;
Ukasi, Sirinya
;
Pakawanit, Phakkhananan
;
Supansomboon, Supitcha
Biopolymer-based triboelectric nanogenerators (B-TENGs) are promising power sources for sustainable and flexible electronics, but their performance is often limited by severe charge recombination at the triboelectric interface. To overcome this critical bottleneck, we report an architected multilayer B-TENG featuring a silk fibroin (SF)/MgAl LDH composite as the charge-generating layer and, to our knowledge, for the first time, a lignin-functionalized SF film as a dedicated charge-trapping layer. The strategic incorporation of lignin, an abundant and sustainable biopolymer, introduces deep-level electronic trapping states originating from its abundant aromatic moieties. That effectively suppresses interfacial charge recombination and prolongs charge lifetime. By optimizing the contents of MgAl LDH and lignin, the device achieves a measured open circuit output voltage ( V <inf> OC </inf>) and current density ( J <inf> SC </inf>) of 96 V and 6.56 μA/cm3, with a maximum output power ( P <inf> max </inf>) of 205 μW, corresponding to a power density of 22.7 μW/cm2. We also propose a mechanistic linking of deep-level traps to prolonged charge lifetime and increased net transferable charge. The interface-engineering strategy demonstrated here paves the way for developing high-performance and sustainable biopolymer-based TENGs and motion sensors.
Some of the metrics are blocked by your
consent settings
Flexible and Self-Powered Wearable Sensors for Tremor Monitoring in Parkinson'S Disease: Recent Advances in Materials and Device Architectures
(2026-01-01)
Ukasi, Sirinya
;
Hajra, Sugato
;
Kim, Hoe Joon
;
Sriphan, Saichon
;
Pongampai, Satana
Parkinson's disease (PD) is a progressive neurodegenerative disorder where tremor remains one of the most prominent and disabling motor symptoms. Traditional clinical rating scales for disease severity rely on clinician observation and patient self-report, often failing to capture the dynamic and continuous nature of tremors in daily life. This drives the development of objective monitoring technologies, such as wearable sensors, for more accurate evaluation of PD severity. However, many existing systems use rigid materials that lack the mechanical compliance and skin conformability required for stable biointegration. This review summarizes advances in flexible wearable sensors for PD tremor assessment from material innovations to a device engineering perspective, covering inertial measurement units (IMUs), electromyography (EMG), and emerging self-powered systems such as triboelectric (TENG) and piezoelectric nanogenerators (PENG). This review highlightshow functional materials, microstructural design, and device architectures govern sensing mechanisms and performance, with particular emphasis on the transition from rigid components to soft, skin-interfaced technologies. Recent patent activity reflects a shift toward multimodal, wireless, and clinically integrated platforms. Despite progress, challenges remain, including motion artifacts, durability, and limited large-scale clinical validation. Integration of flexible materials, self-powered designs, and AI-driven analytics enables continuous, personalized monitoring, moving closer to real-world clinical deployment and improved patient care.
Some of the metrics are blocked by your
consent settings
Piezoelectric composite films for real-time foot strike detection and energy generation
(2025-12-16)
Panpho, Phakakorn
;
Charoonsuk, Thitirat
;
Vittayakorn, Naratip
;
Charoenthai, Nipaphat
;
Bongkarn, Theerachai
Energy harvesting technology integrated into running shoes enables the conversion of mechanical energy from foot strikes into electrical signals for real-time monitoring. This approach enhances running efficiency, reduces injury risk, and eliminates the need for external power sources. In this study, composite films combining lead-free piezoelectric ceramics (KNNS-BNZ-xBF) with PDMS were developed for efficient energy harvesting and accurate detection of foot-strike patterns. XRD analysis revealed a broad R–O–T phase coexistence zone (0 ≤ x ≤ 0.006) and a transition to an R–T phase boundary for x > 0.006, with reduced grain size as xBF increased. The sample with xBF = 0.006 mol.% showed optimal electrical properties and was selected for composite film fabrication. Electrical output increased with ceramic loading, reaching maximum open-circuit voltage (V<inf>OC</inf>) and short-circuit current (I<inf>SC</inf>) at 18 wt% KBB due to enhanced piezoelectric response and uniform particle dispersion. The films, mounted on running shoe soles, successfully detected different foot-strike patterns (heel strike, midfoot, and forefoot). This system demonstrates strong potential for wearable sensors in athletic monitoring and injury prevention.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results