Conformal manufacturing of soft deformable sensors on the curved surface

Health monitoring of structures and people requires the integration of sensors and devices on various 3D curvilinear,hierarchically structured,and even dynamically changing surfaces.Therefore,it is highly desirable to explore conformal manufacturing techniques to fabricate and integrate soft deformable devices on complex 3D curvilinear surfaces.Although planar fabrication methods are not directly suitable to manufacture conformal devices on 3D curvilinear surfaces,they can be combined with stretchable structures and the use of transfer printing or assembly methods to enable the device integration on 3D surfaces.Combined with functional nanomaterials,various direct printing and writing methods have also been developed to fabricate conformal electronics on curved surfaces with intimate contact even over a large area.After a brief summary of the recent advancement of the recent conformal manufacturing techniques,we also discuss the challenges and potential opportunities for future development in this burgeoning field of conformal electronics on complex 3D surfaces.

Effect of cathode composition on microstructure and tribological properties of TiBN nanocomposite multilayer coating synthesized by plasma immersion ion implantation and deposition

Nanocomposite multilayer TiBN coatings were prepared on Si(100) and 9Cr18Mo substrates using TiBN composite cathode plasma immersion ion implantation and deposition technique(PIIID). Synthesis of TiBN composite cathodes was conducted by powder metallurgy technology and the content of hexagonal boron nitride(h-BN) was changed from 8% to 40%(mass fraction). The as-deposited coatings were characterized by energy dispersive spectrometer(EDS), grazing incidence X-ray diffraction(GIXRD), Fourier Transform Infrared Spectroscopy(FTIR) and high resolution transmission electron microcopy(HRTEM). EDS results show that the B content of the coatings was varied from 3.71% to 13.84%(molar fraction) when the composition of the h-BN in the composited cathodes was changed from 8 % to 40%(mass fraction). GIXRD results reveal that the TiBN coatings with a B content of 8% has the main diffraction peak of TiN(200),(220) and(311), and these peaks disappear when the B content is increased. FTIR analysis of the multilayer coatings showed the presence of h-BN in all coatings. TEM images reveal that all coatings have the characteristics of self-forming nanocomposite multilayers, where the nanocomposites are composed of face-centered cubic Ti N or h-BN nanocrystalline embedded in amorphous matrix. The tribological tests reveal that the Ti BN coatings exhibit a marked decrease of coefficient at room temperature(~0.25). The improved properties were found to be derived from the comprehensiveness of the self-forming multilayers structure and the h-BN solid lubrication effects in the coatings.

Nontrivial Topological States in BaSn5 Superconductor Probed by de Haas–van Alphen Quantum Oscillations

We report the nontrivial topological states in an intrinsic type-Ⅱ superconductor BaSn_(5)(T_(c)∼4.4 K)probed by measuring the magnetization,specific heat,de Haas–van Alphen(dHvA)effect,and by performing first-principles calculations.The first-principles calculations reveal a topological nodal ring structure centered at the H point in the k_(z)=πplane of the Brillouin zone,which could be gapped by spin-orbit coupling(SOC),yielding relatively small gaps below and above the Fermi level of about 0.04 eV and 0.14 eV,respectively.The SOC also results in a pair of Dirac points along theΓ–A direction,located at∼0.2 eV above the Fermi level.The analysis of the dHvA quantum oscillations supports the calculations by revealing a nontrivial Berry phase originating from the hole and electron pockets related to the bands forming the Dirac cones.Thus,our study provides an excellent avenue for investigating the interplay between superconductivity and nontrivial topological states.

de Haas–van Alphen Quantum Oscillations in BaSn3 Superconductor with Multiple Dirac Fermions

Characterization of Fermi surface of the BaSn3 superconductor(Tc~ 4.4K)by de Haas–van Alphen(dHvA)effect measurement reveals its non-trivial topological properties.Analysis of non-zero Berry phase is supported by the ab initio calculations,which reveals a type-II Dirac point setting and tilting along the high symmetric K–H line of the Brillouin zone,about 0.13 eV above the Fermi level,and other two type-I Dirac points on the high symmetric Г–A direction,but slightly far below the Fermi level.The results demonstrate BaSn3 as an excellent example hosting multiple Dirac fermions and an outstanding platform for studying the interplay between nontrivial topological states and superconductivity.

Integration of flexible,recyclable,and transient gelatin hydrogels toward multifunctional electronics

Facing the challenges posed by exponentially increasing e-waste,the development of recyclable and tran-sient electronics has paved the way to an environmentally-friendly progression strategy,where electron-ics can disintegrate and/or degrade into eco-friendly end products in a controlled way.Natural polymers possess cost and energy efficiency,easy modification,and fast degradation,all of which are ideal prop-erties for transient electronics.Gelatin is especially attractive due to its unique thermoreversible gelation processes,yet its huge potential as a multifunctional electronic material has not been well-researched due to its limited mechanical strength and low conductivity.Herein,we explored versatile applications of gelatin-based hydrogels through the assistance of multifunctional additives like carbon nanotubes to enhance their electromechanical performances.The optimized gelatin hydrogel displays not only a high conductivity of 0.93 S/m,electromagnetic shielding effectiveness of 39.6 dB,and tensile stress tolerance of 263 kPa,but also shows a negative permittivity phenomenon,which may find versatile applications in novel electronics.As a proof of concept,hydrogels were assembled as wearable sensors to sensitively de-tect static and dynamic pressures and strains generated by solids,liquids,and airflow,as well as diverse body movements.Furthermore,the recyclability,biocompatibility,and degradability of gelatin-based hy-drogels were well studied and analyzed.This work outlines a facile method to design multifunctional transient materials for wearable,sustainable,and eco-friendly electronics.

Dual topology in van der Waals-type superconductor Nb_(2)S_(2)C

Nb_(2)S_(2)C is a van der Waals type layered superconductor with a transition temperature Tc=7.6 K.In this paper,detailed calculations of the electronic structure and topological properties of Nb_(2)S_(2)C were performed from first principles.We find that Nb2S2C is a highly anisotropic metal with multi-band characteristics.In the absence of spin-orbit coupling(SOC),there appears one pair of triply degenerate points created by band inversion along the Γ-A line.When SOC is considered,the triple points are gapped.Intriguingly,two distinct types of topological states,including topological Dirac semimetal and topological insulator states,co-emergence in the vicinity of Fermi level.Moreover,the topology of Nb_(2)S_(2)C is robust to external pressure and the Fermi level can be shifted downward to the topological Dirac semimetal state and topological insulator state at 10 GPa and 14 GPa,respectively.The results herein provide a new platform not only for the studies of physics of low-dimensional superconductor but also for further investigations of topological superconductivity.