npj Flexible Electronics最新文献

Mechanical reliability plays a critical role in determining the durability of flexible electronic devices because of the significant mechanical stresses they experience during manufacturing and operation. Many such devices are built on sheets comprising stiff transparent-conducting oxide (TCO) electrode films on compliant polymer substrates, and it is generally assumed that the high-toughness polymer substrates do not crack. Contrary to this assumption, here we show extensive cracking in the polymer substrates during bending of a variety of TCO/polymer sheets, and a device example — flexible perovskite solar cells. Such substrate cracking, which compromises the overall mechanical integrity of the entire device, is driven by the amplified stress-intensity factor caused by the elastic mismatch at the film/substrate interface. To mitigate this substrate cracking, an interlayer-engineering approach is designed and experimentally demonstrated. This approach is potentially applicable to myriad flexible electronic devices, with stiff films on compliant substrates, for improving their durability and reliability.

Organic electrochemical transistors (OECTs) are promising technologies for biosensing and brain-inspired computing due to their low-power signal amplification and neuron-like behavior. However, their manufacturing remains complex, especially when fabricated into flexible forms. To address the growing demand for flexible OECTs in wearable bioelectronics, in this work, we propose: i) a rapid and low-cost fabrication approach using flexible PCB (fPCB) technology and customized inkjet printing; ii) a non-aqueous gel-gated approach to improve the electrochemical stability of flexible OECTs associated with fPCBs; and iii) the above two approaches help accomplish the following concept: low-cost, integrated, and in-sensing computing system can be more readily realized with flexible OECT devices. This platform has been validated for scalability, stability, and performance in real-world applications, paving the way for developing low-cost, flexible, multifunctional OECT systems.

Cylindrical ferromagnetic tubes are notable for their geometry-driven physical phenomena, making them promising for future technological applications. Self-assembly rolling technology is used to create tubes with high surface quality and side edges, which are crucial for customizing magnetic anisotropy through magnetostatic interactions at the edges. This study investigates the anisotropy induced by these interactions in magnetostriction-free permalloy membranes. Thin planar membranes of varying dimensions were transformed into tubular structures with curvature radii in the tens of microns and winding numbers from 0.6 to 1.5. Experimental results reveal that magnetostatic energy is minimized when the winding number exceeds 0.8–0.9 by adopting an azimuthal domain pattern, or flux-closure configuration, from previously axial domains. These results are supported by analytical calculations of the equilibrium magnetic state of both planar and curved membranes, considering shape anisotropy constants. These constants were derived from magnetostatic energy calculations assuming a single domain configuration and applied to various geometries and curvatures. This research advances the understanding of anisotropy tuning in curved thin-film architectures, focusing on achieving azimuthal magnetic anisotropy in soft ferromagnetic tubular structures without additional induced anisotropy, a key step for applications in data storage, field sensors, and biomedicine relying on 3D magnetic structures.

Shape memory alloy (SMA) fibers demonstrate exceptional contraction strains and substantial load capacities, positioning them as highly promising actuators for advanced robotic hands and microrobotic systems. However, the practical deployment of SMAs has been critically hindered by their inherently slow thermal responsiveness and reliance on wired electrical connections. Here, we introduce a dual-responsive SMA technology that addresses these limitations by leveraging a novel surface modification comprising polydopamine integrated with silver nanowires. The modified SMA fibers exhibited an approximately 3.2 times faster actuation speed than unmodified fibers under near-infrared laser irradiation, with a 35% improvement in electrothermal responsiveness. These wireless, fast-responding actuators have been effectively integrated into microrobotic crawlers, demonstrating great potential for lightweight autonomous lunar rover applications. Fabricated via straightforward in-situ polymerisation methods, our dual-responsive SMA approach offers a compelling pathway toward the development of energy-efficient aerospace systems capable of operating reliably under extreme environmental conditions.

Artificial skins are essential for bridging sensory gaps between robots and environments, enabling natural and intuitive interactions. While artificial skins can sense stimuli like pressure and stretchability, their capabilities need to be expanded into chemical sensing for specific applications. Here, we introduce optical/electronic artificial skins (oe-skins), advancing robotic sensing from physical perception to chemical sensation. Our design integrates optical fibers into a carbon nanotube (CNT)-based haptic electronic skin. This empowers the skin to sense force and temperature, while detecting near-infrared (NIR) optical signals from molecules, giving dual modalities of physical and chemical sensing. We successfully implement the oe-skin into robots, enabling intraocular pressure and glucose level detection for diagnosing glaucoma and diabetes. Additionally, we demonstrated their effectiveness in delicately harvesting fruits and grading them by ripeness, firmness, and sugar levels. We present a blueprint for next-generation intelligent electronics where technological progress aligns with sustainable development and societal well-being.

Flexible actuators have significant potential in intelligent micromachines, artificial muscle, and soft robotics. However, achieving actuators with high actuation performance and feedback sensitivity remains challenging. Inspired by the dual “command-execution-feedback” of the mimic octopus, a fiber actuator with high stroke and visual-electronic dual feedback is designed by introducing an ionic liquid conductive network and a visual component of spiropyrane. By constructing a unique interchain slipping structure inside the liquid crystal elastomer (LCE), the nematic to isotropic transition temperature and maximum stroke temperature dropped to 24.29 °C and 62.3 °C, with decreases of 73.51% and 39.28%, respectively. Besides, the actuation stroke increases to 43.41% with an improvement of 77.11%, and the feedback sensitivity reaches to 69.17, along with a high work capacity of 189.12 kJ/m³. These provide a promising strategy for next-generation flexible actuators capable of high work capacity, large stroke, and real-time feedback.

Achieving precise, localized drug delivery within the brain remains a major challenge due to the restrictive nature of the blood–brain barrier and the risk of systemic toxicity. Here, we present a fully soft neural interface incorporating a thermo-pneumatic peristaltic micropump integrated with asymmetrically tapered microchannels for targeted, on-demand wireless drug delivery. All structural and functional components are fabricated from soft materials, ensuring mechanical compatibility with brain tissue. The system employs sequential actuation of microheaters to generate unidirectional airflow that drives drug infusion from an on-board reservoir. The nozzle–diffuser geometry of the microchannels minimizes backflow while enabling controlled, continuous delivery without mechanical valves. Fluid dynamics simulations guided the optimization of the microfluidic design, resulting in robust forward flow with minimal reflux. Benchtop validation in brain-mimicking phantoms confirmed consistent and programmable drug infusion. This platform represents a significant advancement in neuropharmacological research and therapeutic delivery for central nervous system disorders.

Fiber-based electronic devices (FEDs) exhibit high flexibility, low weight, and excellent integrability into wearable, implantable, and robotic systems. Recent advances have enabled applications in sensing, energy harvesting, and storage, and active functions. Despite this progress, challenges such as mechanical fatigue, interfacial delamination, and signal instability remain. This review offers key challenges and perspectives on the future of FEDs as interactive, autonomous platforms for next-generation electronics in healthcare, robotics, and beyond.

Chiral π-conjugated polymers are key for advancing flexible circularly polarized light (CPL) photodetectors due to their mechanical flexibility, high sensitivity, and compatibility with large-scale fabrication. However, achieving strong CPL detection and efficient charge transport in flexible chiral photodetectors remains challenging. Here, we present a novel n-type chiral π-conjugated polymer (S/R)-P(NDI2MH-T2) for high-performance flexible CPL photodetectors. The polymer exhibits enhanced chiroptical activity after annealing, with significant improvement in |g_abs| at 382 nm (2.34 × 10⁻²) and at 670 nm (1.38 × 10⁻²), which is attributed to improved polymer chain stacking and exciton coupling, as confirmed by molecular dynamics simulations. The phototransistors show high electron mobility (7.9 × 10⁻² cm² V⁻¹ s⁻¹), photoresponsivity (92 A W⁻¹), and detectivity (1.1 × 10¹² Jones). A flexible CPL photodetector fabricated with polydimethylsiloxane and polyethylene naphthalate substrates demonstrates reliable CPL detection with |g_ph| of 0.043. This work highlights the potential of chiral π-conjugated polymers for efficient flexible CPL photodetectors.

Long-term epidermal monitoring with wearable electronics is often hindered on hairy skin due to hair regrowth, which disrupts the skin-device interface and can damage the device. Here, we introduce a high-precision microfiber epidermal thermometer (MET) designed for deformation-insensitive, durable, reliable performance on hairy skin. MET utilizes a stretchable fiber (~340 µm diameter), smaller than average hair follicle spacing, enabling conformal contact without interference from growing hair. Localized nanofiber reinforcement on a microfiber and temperature-sensing layer on localized region create a strain-engineered architecture, allowing MET to achieve strain-insensitive temperature detection. MET demonstrates stable operation under repeated strains (up to 55%) and delivers exceptional precision, with a temperature resolution of 0.01 °C, even during body movements. It accurately tracks physiological temperature fluctuations and provides consistent measurements over 26 days of continuous wear, remaining unaffected by hair regrowth or motion. These results highlight MET as a robust platform for long-term temperature monitoring on hairy skin.