Tunable Piezoresistivity from Magnetically Aligned Ni(Core)@Ag(Shell) Particles in an Elastomer Matrix

Structural and electronic changes in the Ni13@Ag42 nanoparticle under surface oxidation: the role of silver coating

Icosahedral Ni13@Ag42 is a stable nanoparticle formed by a magnetic nickel core surrounded by a silver coating that provides physical protection to the 3d metal cluster as well as antibacterial properties. In this work, we report density functional theoretical calculations to delve into a comprehensive analysis of how surface oxidation impacts the structural, electronic, magnetic, and reactivity properties of this interesting nanoparticle. To elucidate the role played by the silver coating, we compare the results with those found for the bare Ni13 cluster also subjected to surface oxidation. When Ni13 is covered by silver, we find a markedly robust behavior of the magnetic moment of the resulting nanoparticle, which remains nearly constant upon oxidation up to the rates explored, and the same holds for its overall reactivity. The obtained trends are rationalized in terms of the complex interplay between Ni-Ag and Ag-O interactions which impact the relative inter-atomic distances, charge transfer effects, spin polarization and magnetic couplings.

Remarkable Conductive Anisotropy of Ag-Coated Glass Microbeads/UV Adhesive Composites Made by Electric Field Induced Alignment

We successfully prepared highly anisotropic conductive composites (ACCs) made of Ag-coated glass microbeads/UV adhesive via electric field-induced alignment, which was achieved using custom patterned microelectrode arrays. An optimized AC electric field (2 kV/cm, 1 kHz) with pole-plate spacing (50 μm) was utilized to effectively assemble the microbeads into chain arrays, which were precisely positioned on the microelectrode arrays to construct ordered conductive channels. In this case, tangling and cross-connection of the assembled microchains could be reduced, resulting in enhanced performance of the ACCs with high conductivity as well as excellent anisotropy. With a minor loading (3 wt %), the conductivity in the alignment direction could reach ∼24.9 S/m, which was the highest among the reported ACCs to the best of our knowledge, and it could also be 6 orders of magnitude higher than that within the plane. Besides, the samples exhibited high reliability in wire connections with low resistances. Due to these fascinating properties, the ACCs demonstrate promising applications for reliable electrical interconnects and integrated circuits.

A Flexible and Ultra-Highly Sensitive Tactile Sensor through a Parallel Circuit by a Magnetic Aligned Conductive Composite

The development of flexible electronic skins with high performance and multifunctional sensing capabilities is of great significance for applications ranging from healthcare monitoring to artificial intelligence. To mimic and surpass the high-gauge-factor sensing properties of human skin, structure design and appropriate material selection of sensors are both essentially required. Here, we present an efficient, low-cost fabrication strategy to construct an ultra-highly sensitive, flexible pressure sensor by embedding the aligned nickel-coated carbon fibers (NICFs) in a polydimethylsiloxane (PDMS) substrate. Our design substantially contributes to ultrahigh sensitivity through the parallel circuit formed by aligned NICFs as well as surface spinosum microstructure molded by sandpaper. As a result, the sensor exhibits excellent sensitivity (15 525 kPa^-1), a fast response time (30 ms), and good stability over 3000 loading-unloading cycles. Furthermore, these superior sensing properties trigger applications in water quality and wave monitoring in conjunction with mechanical flexibility and robustness. As a precedent for adjusting the sensitivities of the sensor, the NICFs/PDMS sensor provides a promising method for multiscenario healthcare monitoring, multiscale pressure spatial distribution, and human-machine interfacing.