Kar Ban Tan

A flexible radio frequency identification (RFID) temperature-sensing tag is designed for the ultrahigh frequency (UHF) band. The tag employs a T-match structure and a meander-line structure to achieve impedance matching with the chip and miniaturization (72.6 × 20.0 × 0.2 mm). The tag body utilizes copper film and polyimide to realize flexibility. The influence of key parameters on tag characteristics is investigated through simulation. The designed antenna exhibits a resonant frequency of 907 MHz, an operating bandwidth of 32 MHz, and a theoretical reading distance of 6.05 m. The results demonstrate that the tag can operate normally when attached to various parts of the human body, providing a maximum reading range of 1.82 m, with temperature measurement error controlled within 0.15 °C. Compared with conventional temperature sensor tags, the proposed tag shows better impedance matching on the human body, greater flexibility, longer reading distance and better human tissue dielectric compatibility.

Polymer film capacitors are widely used in electronic devices and power systems, yet their energy storage performance (ESP) deteriorates significantly under harsh operating conditions. Here, we propose a synergistic strategy that integrates bulk physical crosslinking with interfacial plasma regulation to suppress conduction loss and enhance high‐temperature dielectric performance. 4‐cyanobenzaldehyde (4‐CZ) is incorporated into a polyetherimide (PEI) matrix to construct a noncovalent, electrostatically crosslinked network, which simultaneously constrains polymer chain dynamics and introduces charge‐transport barriers, thereby effectively inhibiting carrier migration. In parallel, plasma surface treatment further enhances interfacial trap density and suppresses charge injection. Owing to this synergistic regulation of bulk and interface, the optimized film delivers a discharge energy density ( U _d ) of ∼7.6 J·cm ⁻³ with an efficiency ( η ) of 91.8% at 150°C and 670 MV·m ⁻¹ , markedly outperforming pristine PEI. This work establishes a generalizable design strategy for high‐performance all‐organic polymer dielectrics toward high‐temperature energy storage applications.

1. Oxide-ion conducting solid electrolytes are critical components in various energy and environmental technologies, including solid oxide fuel cells (SOFCs), oxygen sensors and oxygen pumps. These...

Thermal cycling failure of solder joints in surface-mount passive components represents a core bottleneck limiting the reliability of next-generation high-frequency communication systems. Conventional microwave dielectric ceramics exhibit low coefficients of thermal expansion (CTE, 5–12 ppm/°C), causing severe thermal mismatch with commercial SAC305 lead-free solder (21.9 ppm/°C) and copper conductors, which generates enormous thermal stress and induces solder joint cracking during temperature cycling. Herein, we report an intrinsically high-CTE microwave dielectric ceramic Na3P3O9 with a CTE of 22.25 ppm/°C, matching almost perfectly with SAC305 solder. At its optimal sintering temperature of 610 °C, this material simultaneously possesses an ultralow permittivity (εr = 4.88) and ultralow dielectric loss (on the order of 10–4). The physical origins of its excellent comprehensive properties are elucidated via crystal structure analysis and chemical bond theory. Finite element simulations reveal that under the standard electronic packaging thermal cycling condition of –40 to 125 °C, the thermal stress of solder joints on Na3P3O9 is only 54% of that on commercial A6M and 30% of that on conventional alumina. A Ku-band broadband dielectric resonator antenna designed using this material achieves an impedance bandwidth of 3.1 GHz and an in-band total efficiency of >87.2%, fully covering the transmit and receive bands of fixed-satellite and broadcasting satellite services and enabling transmit-receive integration for low Earth orbit satellite terminals. This work provides a high-CTE dielectric material system for addressing the solder joint reliability issue in high-frequency passive components.

Electrochromic (EC) technology has garnered attention for its low energy consumption and aesthetic versatility. Among various EC materials, tungsten trioxide (WO₃) is notable for its high optical contrast, durability, and coloration efficiency. However, its single-color output limits its versatility in applications such as multicolor displays and windows. In addition, conventional complementary EC devices require the pairing of anodic and cathodic materials, restricting independent control of redox reactions on the electrodes. Hence, this study introduced a three-electrode EC energy storage device with various configurations: vanadium oxide/zinc/vanadium oxide (V₂O₅/Zn/V₂O₅) (energy status indicator) and V₂O₅/Zn/WO₃ (energy storage window and multicolor display). This design allowed independent redox control on both electrodes, enhanced multicolor functionality through V₂O₅, and incorporated zinc metal for efficient energy storage and discharge-induced coloration. The study revealed that V₂O₅/Zn/V₂O₅ configuration exhibited higher coloration depth (58.92% for orange, 32% for yellow-green, and 10.65% for blue) across all color states while achieving a high energy storage capacity of 185 mAh/m², making it ideal for energy status indicator applications. Conversely, the V₂O₅/Zn/WO₃ structure achieved a significantly higher optical contrast of 77.86%, excellent coloration efficiency of 46.24 cm²/C, and energy storage capacities of 104.8 mAh/m² (V₂O₅) and 142 mAh/m² (WO₃), making it suitable for multicolor energy storage windows. Additionally, the V₂O₅/Zn/WO₃ configuration demonstrated suitability for multicolor display applications. Overall, these three-electrode EC energy storage architectures address the intrinsic color limitations and redox control constraints of conventional devices, enabling high-capacity, tunable multicolor operation with significant potential for integration into advanced smart windows, energy indicators, and adaptive display technologies.