We describe in this work Mg electrodeposition and dissolution from a wide range of inorganic ethereal electrolytes consisting of MgCl2 and a second chloride salt. Systematic variations of the cosalt ...reveal two broad classes of electrolytes, namely, the group 13 electrolytes, which require electrolytic cycling to improve their performance, and electrolytes based on heavy p-block chlorides, which exhibit Mg intermetallic formation. Results from electrospray ionization mass spectrometry demonstrate that Mg deposition and stripping only occur in electrolytes containing Mg multimers. We also explore the role of solvent in determining the electrochemical performance of chloride-based electrolytes. Our analysis establishes thermodynamic parameters that dictate the ability of a solvent to support Mg electrochemistry in the MgCl2–AlCl3 system. In their totality, these results illustrate important electrolyte design guidelines for future Mg-ion batteries.
Flexible, stretchable, and spanning microelectrodes that carry signals from one circuit element to another are needed for many emerging forms of electronic and optoelectronic devices. We have ...patterned silver microelectrodes by omnidirectional printing of concentrated nanoparticle inks in both uniform and high-aspect ratio motifs with minimum widths of approximately 2 micrometers onto semiconductor, plastic, and glass substrates. The patterned microelectrodes can withstand repeated bending and stretching to large levels of strain with minimal degradation of their electrical properties. With this approach, wire bonding to fragile three-dimensional devices and spanning interconnects for solar cell and light-emitting diode arrays are demonstrated.
We developed a simple approach to combine broad classes of dissimilar materials into heterogeneously integrated electronic systems with two- or three-dimensional layouts. The process begins with the ...synthesis of different semiconductor nanomaterials, such as single-walled carbon nanotubes and single-crystal micro- and nanoscale wires and ribbons of gallium nitride, silicon, and gallium arsenide on separate substrates. Repeated application of an additive, transfer printing process that uses soft stamps with these substrates as donors, followed by device and interconnect formation, yields high-performance heterogeneously integrated electronics that incorporate any combination of semiconductor nanomaterials on rigid or flexible device substrates. This versatile methodology can produce a wide range of unusual electronic systems that would be impossible to achieve with other techniques.
This study examines the crystallographic anisotropy of strain evolution in model, single‐crystalline silicon anode microstructures on electrochemical intercalation of lithium atoms. The 3D ...hierarchically patterned single‐ crystalline silicon microstructures used as model anodes were prepared using combined methods of photolithography and anisotropic dry and wet chemical etching. Silicon anodes, which possesses theoretically ten times the energy density by weight compared to conventional carbon anodes, reveal highly anisotropic but more importantly, variably recoverable crystallographic strains during cycling. Model strain‐limiting silicon anode architectures that mitigate these impacts are highlighted. By selecting a specific design for the silicon anode microstructure, and exploiting the crystallographic anisotropy of strain evolution upon lithium intercalation to control the direction of volumetric expansion, the volume available for expansion and thus the charging capacity of these structures can be broadly varied. We highlight exemplary design rules for this self‐strain‐limited charging in which an anode can be variably optimized between capacity and stability. Strain‐limited capacities ranging from 677 mAhg−1 to 2833 mAhg−1 were achieved by constraining the area available for volumetric expansion via the design rules of the microstructures.
Model single‐crystalline silicon systems are used to examine the anisotropies in the evolution of strain during electrochemical lithium intercalation. Quasi 1D, 2D, and 3D design rules passively exploit these anisotropies in order to limit strain on the anode during charge/discharge cycling. Strain‐limited charge capacities ranging from 677 mAhg−1 to 2833 mAhg−1 were achieved.
Complex three-dimensional (3D) structures in biology (e.g., cytoskeletal webs, neural circuits, and vasculature networks) form naturally to provide essential functions in even the most basic forms of ...life. Compelling opportunities exist for analogous 3D architectures in human-made devices, but design options are constrained by existing capabilities in materials growth and assembly. We report routes to previously inaccessible classes of 3D constructs in advanced materials, including device-grade silicon. The schemes involve geometric transformation of 2D micro/nanostructures into extended 3D layouts by compressive buckling. Demonstrations include experimental and theoretical studies of more than 40 representative geometries, from single and multiple helices, toroids, and conical spirals to structures that resemble spherical baskets, cuboid cages, starbursts, flowers, scaffolds, fences, and frameworks, each with single- and/or multiple-level configurations.
Properties that can now be achieved with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements for existing infrastructure in general ...illumination, with important implications for efficient use of energy. Further advances in this technology will benefit from reexamination of the modes for incorporating this materials technology into lighting modules that manage light conversion, extraction, and distribution, in ways that minimize adverse thermal effects associated with operation, with packages that exploit the unique aspects of these light sources. We present here ideas in anisotropic etching, microscale device assembly/integration, and module configuration that address these challenges in unconventional ways. Various device demonstrations provide examples of the capabilities, including thin, flexible lighting "tapes" based on patterned phosphors and large collections of small light emitters on plastic substrates. Quantitative modeling and experimental evaluation of heat flow in such structures illustrates one particular, important aspect of their operation: small, distributed LEDs can be passively cooled simply by direct thermal transport through thin-film metallization used for electrical interconnect, providing an enhanced and scalable means to integrate these devices in modules for white light generation.
An increasing number of technologies require large-scale integration of disparate classes of separately fabricated objects into spatially organized, functional systems. Here we introduce an approach ...for heterogeneous integration based on kinetically controlled switching between adhesion and release of solid objects to and from an elastomeric stamp. We describe the physics of soft adhesion that govern this process and demonstrate the method by printing objects with a wide range of sizes and shapes, made of single-crystal silicon and GaN, mica, highly ordered pyrolytic graphite, silica and pollen, onto a variety of substrates without specially designed surface chemistries or separate adhesive layers. Printed p-n junctions and photodiodes fixed directly on highly curved surfaces illustrate some unique device-level capabilities of this approach.
Nanostructured Plasmonic Sensors Stewart, Matthew E; Anderton, Christopher R; Thompson, Lucas B ...
Chemical reviews,
02/2008, Volume:
108, Issue:
2
Journal Article
Peer reviewed
Localized surface plasmon resonance (LSPR) sensors are examined. LSPRs are nonpropagating plasmon excitations that can be on metal nanoparticles and around nanoholes and nanowells in thin metal films.
Three‐dimensional (3D) microperiodic scaffolds of poly(2‐hydroxyethyl methacrylate) (pHEMA) have been fabricated by direct‐write assembly of a photopolymerizable hydrogel ink. The ink is initially ...composed of physically entangled pHEMA chains dissolved in a solution of HEMA monomer, comonomer, photoinitiator and water. Upon printing 3D scaffolds of varying architecture, the ink filaments are exposed to UV light, where they are transformed into an interpenetrating hydrogel network of chemically cross‐linked and physically entangled pHEMA chains. These 3D microperiodic scaffolds are rendered growth compliant for primary rat hippocampal neurons by absorption of polylysine. Neuronal cells thrive on these scaffolds, forming differentiated, intricately branched networks. Confocal laser scanning microscopy reveals that both cell distribution and extent of neuronal process alignment depend upon scaffold architecture. This work provides an important step forward in the creation of suitable platforms for in vitro study of sensitive cell types.
3D microperiodic hydrogel scaffolds with varied architecture are patterned by direct‐write assembly and investigated as culture platforms for primary hippocampal neurons. Neuronal cells thrive on these scaffolds, forming differentiated, intricately branched networks. Confocal laser scanning microscopy reveals that both cell distribution and extent of neuronal process alignment depend upon scaffold architecture.
A 3D mechanically stable scaffold is shown to accommodate the volume change of a high‐specific‐capacity nickel–tin nanocomposite during operation as a Li‐ion battery anode. The nickel–tin anode is ...supported by an electrochemically inactive conductive scaffold with an engineered free volume and controlled characteristic dimensions, which engender the electrode with significantly improved cyclability.
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