npj Flexible Electronics最新文献

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.

Mimicking and extending biological sensory memory processing functions and systems—that play significant roles in enhancing interconnections of the human-physical world—are highly preferable for the Internet of Things. However, conventional artificial sensory systems usually consisted of separated modules or relied on perception-memory-processing devices with applications in a limited domain. Here, we propose a self-rectifying multifunctional synapse based on a unique PN optoelectrical memristor interface, achieving an augmented artificial visual system and multifunctional interconnected ports. The synapse realizes in-sensor motion perception and non-contact control beyond perception-memory-processing functions. The self-rectifying device can self-suppress the sneak current in cross-arrays, enabling large-scale and high-density integration. Further integrating synapse with quantum dot light-emitting diodes (QLEDs) evolves more powerful functions like hardware noise filtering and perception-memory-processing-displaying smart systems.

The increasing demand for adaptable, lightweight, and efficient pump systems in engineering and medical fields highlights the limitations of traditional rigid pumps, which are bulky, noisy, and inflexible. Despite advancements in smart materials and electro-hydrodynamics (EHD), flexible pumps face challenges from structural rigidity and performance constraints. Here, we develop a customizable soft fiber pump (CSFP) that utilizes wound printed flexible electrodes alongside thermoplastic tubes. This innovative approach enables variable electrode configurations, tunable internal diameters, and modifiable cross-sectional geometries, significantly enhancing the pump’s performance and adaptability. The fabrication method yields a compact structure with intergrated electrodes, reconfigurable cross-sections, and flow orientation control. With these features, the CSFP achieves a pressure gradient of 1.39 kPa/cm and a specific flowrate of 160 mL/min/g. These capabilities support its use in soft actuation, conformal thermal management, and redirected flow for impurity separation, demonstrating potential for integration into a broad range of technological and industrial applications.

This paper provides a comprehensive review of the research progress in paper-based flexible electronic devices, focusing on key aspects such as the physical and chemical properties of paper substrates, device structures, fabrication methods for electrodes and active layers, and their diverse applications. The paper also identifies current challenges facing paper-based electronic devices, such as issues related to long-term stability and the optimization of large-scale production processes.

Reverse-offset printing (ROP) enables microscale patterning on flexible substrates, making it ideal for fabricating interdigital capacitive (IDC) sensors for atopic dermatitis (AD) monitoring. AD, characterized by skin dryness and inflammation, demands precise hydration tracking. Tailoring IDC electrode gaps to 50 µm concentrates the electric field within the stratum corneum (SC), enhancing sensitivity beyond the capabilities of traditional screen printing. Finite element modelling and ROP were employed to assess the impact of electrode geometry and encapsulation thickness on sensor performance. Findings indicate that 50 µm electrodes with encapsulation layers under 10 µm maintain high sensitivity and consistent operation. A clinical case study demonstrated the 50 µm sensor’s ability to distinguish lesional from non-lesional skin. These results inform the optimization of encapsulation–performance balance and advance the design of wearable, high-resolution IDC sensors for continuous skin hydration monitoring in personalized dermatological care.

Electrodes underpin electrophysiological signals recording, requiring stable skin contact and low impedance for high-quality, long-term acquisition. Dry microneedle electrodes penetrate the stratum corneum and bypass hair to ensure robust contact, but conventional rigid designs lack tissue conformity, risking discomfort and injury. This work introduces a modulus-adjustable, mechanically adaptive dry microneedle electrode (MDME) constructed from PEDOT: PSS and shape memory polymer. Submillimeter MDME penetrates skin barriers and, upon body temperature activation, softens to match tissue mechanics, minimizing invasiveness. The MDME exhibits low, stable interface impedance and enables high-quality electromyography, electrocardiography, electroencephalography, and electrocorticography recordings. After one month of usage, the electrophysiological root mean square noise increased by only 6 μV, compared to 63 μV of Ag/AgCl gel electrodes. Electroencephalogram signal-to-noise reached 8.12 dB versus 7.26 dB for the cranial screw electrodes. This work represents a notable advancement in MDME-based electrophysiological recording, expanding its potential applications in personalized healthcare and human-machine interaction.

Stretchable and flexible electronics represent emerging and exciting directions for future electronics, while transfer printing plays an essential and mainstream role in integrating electronics onto application substrates. However, existing transfer printing approaches have restrictions for electronics in terms of stiffness and dimensionality, as well as limitations for substrates in terms of surface and adhesion. Here, we report a versatile soap bubble transfer printing technique that, through a volume modulation strategy, enables the adhesion-independent, damage-free, and low-contamination integration of rigid, flexible, and three-dimensional curved electronics onto substrates with complex surfaces and challenging adhesion. To demonstrate the versatility and compatibility of the soap bubble transfer printing technique, we performed not only special behaviors such as wrap-like, multilayer, selective, and interior printing, but also integrated flexible electronics onto various human organ models, which holds promise for health monitoring in both noninvasive and invasive manners.