npj Flexible Electronics最新文献

Lead Zirconate Titanate (PZT) is a leading piezoelectric material for surface haptics actuators due to its high piezoelectric coefficients and broad frequency response. However, current fabrication methods rely on adhesive bonding of bulk PZT to glass substrates, which is inefficient and labor-intensive. In this study, we developed a modified PZT ink formulation for direct printing onto high-temperature-resistant glass with silver (Ag) electrodes. A major challenge in this approach is the high sintering temperature required for PZT, which can exceed the thermal limits of glass. To overcome this, CuO modification enabled low-temperature sintering at 900 °C. while preserving strong piezoelectric performance (d₃₃: 270–310 pC/N, d₃₁: –40 to –50 pC/N). The resulting actuator generated standing Lamb waves at 36 kHz, achieving a displacement of 1.2 µm under a low driving voltage of 10 V_pp. These results demonstrate the feasibility of CuO-modified, ink-printed PZT for efficient, high-performance piezoelectric surface haptic actuators.

This study presents a low residual tensile stress, flexible thin film encapsulation with a 2 mm bending radius based on atomic layer deposition (ALD), specifically plasma-enhanced ALD (PEALD). By utilizing polydimethylsiloxane (PDMS) to release stress during deposition, we achieved a wrinkled morphology film that reduces stress magnitude from 10³ to 10² compared to conventional Al₂O₃ films. This wrinkled film enhances optical modulation to light extraction, increasing the external quantum efficiency (EQE) of organic light-emitting diode (OLED) by up to 14.95%. The water vapor transmission rate (WVTR) is 4.49 × 10⁻⁵g/m²/day at 60 °C/90% RH, and the film retains about 90% of its initial properties after 10,000 bending cycles. This work introduces a novel solution for flexible ALD encapsulation, demonstrating ultra-flexible properties while improving device efficiency.

Triboelectric nanogenerators (TENGs) are promising for self-powered biomedical applications such as wound healing, cancer therapy, and biosensing. However, their dependence on external wires and electrodes limits usability and comfort. Here, we introduce a wire-free approach using dermal conductive tattoos. Unlike conventional systems requiring a back conductor, our method uses skin as the triboelectric layer, with charge transferred via subdermal conductive tattoos—eliminating external accessories. This concept was validated through triboelectric testing of skin, tattoo performance on artificial models, bioresorbable ink development, and in vivo voltage generation. The system successfully accelerated wound healing in freely walking animals, powered solely by body motion. The use of bioresorbable zinc-based inks enabled temporary functionality that disappeared naturally with the healing process. Furthermore, the tattooed electrodes can be seamlessly merged with artistic designs, paving the way for next-generation bioelectronic tattoos that are both therapeutic and aesthetically personalized.

Stretchable displays can withstand greater deformation than traditional displays, enabling their versatile integration into various electronic devices. However, when conventional stretchable displays are stretched, pixel size or spacing increases, reducing image quality. Various methods have been tried to maintain resolution, but the fill factor decreases when all pixels are active during stretching. Here, integrated stretchable OLEDs are presented with an integrated pixel density by overlapping quadrant pixels in voids. Overlapped pixels are vertically aligned to optically function as a single pixel in the original state. Upon stretching, these pixels are spatially separated and become individually visible, thereby increasing the fill factor. A reliable multilayered structure is designed through the patterned adhesive and the deposition of patterned electrodes. The PM-integrated stretchable display, consisting of a 3 × 2 array with one central pixel and four quadrant pixels per unit, successfully displayed various letters clearly in both the original and stretched states.