The ability to engineer microscale and nanoscale morphology upon metal nanowires (NWs) has been essential to achieve new electronic and photonic functions. Here, this study reports an optically programmable Plateau−Rayleigh instability (PRI) to demonstrate a facile, scalable, and high-resolution morphology engineering of silver NWs (AgNWs) at temperatures <150 °C within 10 min. This has been accomplished by conjugating a photosensitive diphenyliodonium nitrate with AgNWs to modulate surface-atom diffusion. The conjugation is UV-decomposable and able to form a cladding of molten salt-like compounds, so that the PRI of the AgNWs can be optically programmed and triggered at a much lower temperature than the melting point of AgNWs. This PRI self-assembly technique can yield both various novel nanostructures from single NW and largearea microelectrodes from the NW network on various substrates, such as a nanoscale dot-dash chain and the microelectrode down to 5 μm in line width that is the highest resolution ever fabricated for the AgNW-based electrode. Finally, the patterned AgNWs as flexible transparent electrodes were demonstrated for a wearable CdS NW photodetector. This study provides a new paradigm for engineering metal micro-/nanostructures, which holds great potential in fabrication of various sophisticated devices.

Wearable sensor technology is essential to achieve personalized health management via continuous monitoring of individual health status. Although diaper-based biosensors have been developed, multiplex strategies for biomolecular sensing of urine in situ are still rarely investigated, which limits a comprehensive assessment of the wearer’s health information from urine. In this study, we present a mechanically flexible and smart diaper based on integrated multiplex electrochemical sensors (MECSs) for in situ urinalysis that simultaneously and selectively measures urinary metabolites (e.g., glucose, reactive oxygen species with H2O2 as an example, and uric acid) and electrolytes, including sodium and potassium ions. The sensor electrode arrays were modified with carbon nanotube coatings and chemical substances (ion-selective membranes, enzymes, or Pt nanoparticles) to achieve highly selective and sensitive monitoring of target biomarkers associated with urine status. The MECSs could be further prepared into a prototype that integrates a biosensor module, flexible circuit board, and Bluetooth signal transmitter to provide a promising substitute for monitoring for bedside patients, infants, and senior citizens.

Monitoring human health is of considerable significance in biomedicine. In particular, the ion concentrations in blood are important reference indicators related to many diseases. Microneedle array-based sensors have enabled promising breakthroughs in continuous health monitoring due to their minimally invasive nature. In this study, we developed a microneedle sensing-array integrated system to continuously detect subcutaneous ions to monitor human health status in real time based on a fabrication strategy for assembling planar microneedle sheets to form 3D microneedle arrays. The limitations of preparing 3D microneedle structures with multiple electrode channels were addressed by assembling planar microneedle sheets fabricated via laser micromachining; the challenges of modifying closely spaced microneedle tips into different functionalized types of electrodes were avoided. The microneedle sensing system was sufficiently sensitive for detecting real-time changes in Ca2+, K+, and Na+ concentrations, and it exhibited good detection performance. The in vivo results showed that the ion-sensing microneedle array successfully monitored the fluctuations in Ca2+, K+, and Na+ in the interstitial fluids of rats in real time. By using an integrated circuit design, we constructed the proposed microneedle sensor into a wearable integrated monitoring system. The integrated system could potentially provide information feedback for diseases related to physiological ion changes.

Current catheter devices in minimally invasive surgery still possess limited functional options, lacking multimodal integration of both sensing and therapy. Catheter devices usually operate outside the tissue, incapable to detect intra‐tissue biochemical information for accurate localization and assessment of lesions during surgery. Inspired by the feature and functions of Petromyzontidae, here a multimodal core‐shell microneedles‐integrated bioelectronic catheter (MNIBC) for tissue‐penetrating theranostics in endoscopic surgery is developed. The microneedle (MN) device possesses individually addressable functionality at single‐MN tip resolution, enabling multiplex functions (a total of 11 functions distributed in three types of catheters) including biochemical sensing, myoelectric modulation, electroporation, and drug delivery in a submucosal environment. The MNIBC is prepared through hybrid fabrication and dimensionality reduction strategies, where the MN electrodes are functionalized with an MXene‐carbon nanotube (MXene‐CNT)‐based electron mediator, addressing the challenge of reduced electrode sensitivity on ultra‐small MN tip. The functionalities of MNIBC are demonstrated both ex vivo and in vivo on anesthetized rabbits via laparoscopy, simulated cystoscopy, and laparotomy. The MNIBC can effectively detect intra‐tissue biochemical signals in the bladder, and offers localized electroporation and intra‐tissue drug delivery for precise treatments of lesions. The versatile features of the MNIBC present a highly advanced platform for precise surgeries.