Multiscale Soft–Hard Interface Design for Flexible Hybrid Electronics

Emerging next-generation soft electronics will require versatile properties functioning under mechanical compliance, which will involve the use of different types of materials. As a result, control over material interfaces (particularly soft/hard interfaces) has become crucial and is now attracting intensive worldwide research efforts. A series of material and structural interface designs has been devised to improve interfacial adhesion, preventing failure of electromechanical properties under mechanical deformation. Herein, different soft/hard interface design strategies at multiple length scales in the context of flexible hybrid electronics are reviewed. The crucial role of soft ligands and/or polymers in controlling the morphologies of active nanomaterials and stabilizing them is discussed, with a focus on understanding the soft/hard interface at the atomic/molecular scale. Larger nanoscopic and microscopic levels are also discussed, to scrutinize viable intrinsic and extrinsic interfacial designs with the purpose of promoting adhesion, stretchability, and durability. Furthermore, the macroscopic device/human interface as it relates to real-world applications is analyzed. Finally, a perspective on the current challenges and future opportunities in the development of truly seamlessly integrated soft wearable electronic systems is presented.     

Engineering Functional Membrane–Membrane Interfaces by InterSpy

Engineering synthetic interfaces between membranes has potential applications in designing non-native cellular communication pathways and creating synthetic tissues. Here, InterSpy is introduced as a synthetic biology tool consisting of a heterodimeric protein engineered to form and maintain membrane–membrane interfaces between apposing synthetic as well as cell membranes through the SpyTag/SpyCatcher interaction. The inclusion of split fluorescent protein fragments in InterSpy allows tracking of the formation of a membrane–membrane interface and reconstitution of functional fluorescent protein in the space between apposing membranes. First, InterSpy is demonstrated by testing split protein designs using a mammalian cell-free expression (CFE) system. By utilizing co-translational helix insertion, cell-free synthesized InterSpy fragments are incorporated into the membrane of liposomes and supported lipid bilayers with the desired topology. Functional reconstitution of split fluorescent protein between the membranes is strictly dependent on SpyTag/SpyCatcher. Finally, InterSpy is demonstrated in mammalian cells by detecting fluorescence reconstitution of split protein at the membrane–membrane interface between two cells each expressing a component of InterSpy. InterSpy demonstrates the power of CFE systems in the functional reconstitution of synthetic membrane interfaces via proximity-inducing proteins. This technology may also prove useful where cell-cell contacts and communication are recreated in a controlled manner using minimal components.     

Rational Design of Functional Peptide–Gold Hybrid Nanomaterials for Molecular Interactions

Gold nanoparticles (AuNPs) have been extensively used for decades in biosensing-related development due to outstanding optical properties. Peptides, as newly realized functional biomolecules, are promising candidates of replacing antibodies, receptors, and substrates for specific molecular interactions. Both peptides and AuNPs are robust and easily synthesized at relatively low cost. Hence, peptide–AuNP-based bio-nano-technological approaches have drawn increasing interest, especially in the field of molecular targeting, cell imaging, drug delivery, and therapy. Many excellent works in these areas have been reported: demonstrating novel ideas, exploring new targets, and facilitating advanced diagnostic and therapeutic technologies. Importantly, some of them also have been employed to address real practical problems, especially in remote and less privileged areas. This contribution focuses on the application of peptide–gold hybrid nanomaterials for various molecular interactions, especially in biosensing/diagnostics and cell targeting/imaging, as well as for the development of highly active antimicrobial/antifouling coating strategies. Rationally designed peptide–gold nanomaterials with functional properties are discussed along with future challenges and opportunities.     

Rational Design of a High-Loading Polysulfide Cathode and a Thin-Lithium Anode for Developing Lean-Electrolyte Lithium–Sulfur Full Cells

Lithium-sulfur cells are attractive energy-storage systems because of their high energy density and the electrochemical utilization rates of the high-capacity lithium-metal anode and the low-cost sulfur cathode. The commercialization of high-performance lithium–sulfur cells with high discharge capacity and cyclic stability requires the optimization of practical cell-design parameters. Herein, a carbon structural material composed of a carbon nanotube skeleton entrapping conductive graphene is synthesized as an electrode substrate. The carbon structural material is optimized to develop a high-loading polysulfide cathode with a high sulfur loading capacity (6–12 mg cm⁻²), rate performance (C/10–C/2), and cyclic stability for 200 cycles. A thin lithium anode based on the carbon structural material is developed and exhibits long lithium stripping/plating stability for ≈2500 h with a lithium-ion transference number of 0.68. A lean-electrolyte lithium–sulfur full cell with a low electrolyte-to-sulfur ratio of 6 µL mg⁻¹ is constructed with the designed high-loading polysulfide cathode and the thin lithium anode. The integration of all the critical cell-design parameters endows the lithium–sulfur full cell with a low negative-to-positive capacity ratio of 2.4, while exhibiting stable cyclability with an initial discharge capacity of 550 mAh g⁻¹ and 60% capacity retention after 200 cycles.     

The Study of Magnetically Soft Fe–B–P Based Nanostructures

Rapidly quenched Fe–B–P alloys with addition Cu exhibit high saturation induction, high permeability, low coercivity, and excellent mechanical properties (?vec et al. in IEEE Trans. Magn. 46:408, 2010; Makino et al. in IEEE Trans. Magn. 45(10):4302–4305, 2009; Makino et al. in Ser. Mater. 48:869, 2003). The systems based on Fe–B–P–Cu have been prepared by planar flow casting in form of thin ribbons. Selected magnetic properties in the as-cast state and after controlled annealing targeted to produce fine-grain structure of bcc-Fe in amorphous matrix were determined. The effect of the additions of P and Cu on structure and soft magnetic properties in the nanocrystalline state was investigated. Using the direct magnetostriction measurement method, the magnetostrictions as functions of external magnetic field in parallel and perpendicular directions were determined and the values of saturation magnetostriction λ _s were calculated. The Curie temperature was determined by thermogravimetry analysis (TGA). X-ray diffraction (XRD) and transmission electron microscopy (TEM) investigations at selected temperatures were performed to obtain information about the structure, morphology, size, and distribution of grains in an amorphous matrix, and to correlate microstructure and selected physical properties of the investigated system.     

A Review on Engineering Design for Enhancing Interfacial Contact in Solid-State Lithium–Sulfur Batteries

The utilization of solid-state electrolytes(SSEs) presents a promising solution to the issues of safety concern and shuttle effect in Li–S batteries, which has garnered significant interest recently. However, the high interfacial impedances existing between the SSEs and the electrodes(both lithium anodes and sulfur cathodes) hinder the charge transfer and intensify the uneven deposition of lithium, which ultimately result in insufficient capacity utilization and poor cycling stability. Hence,the...     

Design of Low Cost Broadband Ultrasonic Pulser–Receiver

Determination of ultrasonic propagation velocity in materials provides an insight into their intrinsic and extrinsic properties. The American National Standard, E-494–95 describes an exhaustive procedure of ultrasonic velocity measurement and various material parameters that are based on ultrasonic velocity. Ultrasonic pulser–receiver is a device, used to excite piezoelectric transducers. Further, a oscilloscope or data acquisition device is employed to display and analyze the receiver output. The quality of measured parameter mainly depends on the capabilities of the measurement device used at the receiver. Careful study of the displayed wave pattern enables the detection of deformities inside the metal blocks. In this article, a low cost pulser–receiver designed in the laboratory has been discussed. The design provided can be used by a person having considerable knowledge of electronics to build up a pulser–receiver. The designed device has been tested for its functionality to measure ultrasonic velocity and attenuation. The measured values have been compared with the literature values and are in close agreement with the measurements taken by an imported system.     

Søren Bisgaard’s contributions to Quality Engineering: Design of experiments

Abstract

This article examines Søren’s impact on the design and analysis of experiment through three of his published articles in ASQ journals. These articles demonstrate Søren’s unique blend of engineer and statistician with the ability to see the big picture both of the solution to the specific problem and of the solution strategy for good practice. Søren was a giant in our field who was struck down too early in life by mesothelioma at the age of 58 years. His work, and more importantly his impact on his colleagues, has continued to influence the profession.     

Design and synthesis of inorganic–organic hybrid microstructures

Vanadium oxide–polypyrrole (V₂O₅–PPy) hybrid aerogels were prepared using three different strategies. These approaches were focused on either sequential or consecutive polymerization of the inorganic and organic networks. The hybrid microstructure differed greatly depending on which synthesis approach was used. Microcomposite aerogels were synthesized by encapsulating a dispersion of preformed PPy in a V₂O₅ gel. In the second approach, pyrrole was polymerized and doped within the pore volume of a preformed V₂O₅ gel. The hybrid microstructure of these materials was nanometer scaled but inhomogeneous. When the inorganic and organic precursors were allowed to polymerize simultaneously, the resulting gels exhibited a nanometer-scaled microstructure with a homogeneous distribution of the PPy and the V₂O₅. Through this route, a suitable microstructure and composition for a lithium secondary battery cathode were obtained. Undoped material with a composition of [PPy]_0.8V₂O₅ exhibited a lithium intercalation capacity comparable to that of V₂O₅ aerogel. For the full benefit of the PPy phase to be achieved, a suitable doping procedure is still required to oxidize the PPy into its high conductivity state while preserving the inorganic structure.     

Calcined gypsum–lime–metakaolin binders: Design of optimal composition

The effect of composition on the properties of calcined gypsum–lime–metakaolin pastes is investigated. The components in the calcined gypsum–lime–metakaolin–water system are found to interact synergically; there is no simple way to find the optimum composition. Therefore, an optimization is performed using the sequential simplex method which leads very fast to a significant enhancement of mechanical properties. Already after the first trial the compressive strength is almost two times higher than for the most successful initial mixes designed in a common way without optimization and more than three times higher than for the reference calcined gypsum–lime paste. The bending strength and dynamic modulus of elasticity exhibit similar improvements. In addition, the better mechanical properties are achieved without any negative effect on thermal conductivity and water vapor diffusion coefficient.     

Design and mechanical characterization of a Zr–Nb–O–P alloy

In this study, Sn-free Zr–1.5Nb–O–P alloys were manufactured and their mechanical properties were characterized. The ultimate tensile strength (UTS) of cold rolled Zr–1.5Nb–O–P alloy with 160 ppm phosphorous (680 MPa) were close to that of a commercially available Zr–1Nb–1Sn–0.1Fe alloy (720 MPa), achieving a good mechanical strength without the addition of Sn, an effective solution strengthening element. The UTS of recrystallized Zr–1.5Nb–O–P alloy with 160 ppm phosphorous (533 MPa) was far greater than that of a commercially available Zr–1Nb–O (323 MPa) because of the strengthening due to higher Nb and oxygen content combined with phosphorous strengthening. The activation volumes for the cold rolled Zr–1.5Nb–P alloys were not much different from those of annealed Zr–1.5Nb–P alloys despite the higher dislocation density in the cold rolled alloys. Insensitivity of the activation volume to the dislocation density and the decrease of the activation volume with the addition of phosphorous support the suggestion linking the activation volume with the activated bulge of dislocations limited by segregation of oxygen and phosphorous atoms.     

Design of Zr–Al–Ni–Cu bulk metallic glasses with network structures

A series of Zr–Al–Ni–Cu bulk metallic glasses (BMGs) with network structures were carefully designed and their heterogeneous microstructures were investigated by carefully etching the cross sections of these BMGs. It is found that the heterogeneous microstructures of these BMGs can be uncovered by etching with mixed solution of HF and HNO₃. Some of the studied Zr-based BMGs characterize in micrometer network structure. The cell size of the network structure depends on the composition of the BMG and is related with the fractural mode and mechanical property. The found network structure of the Zr-based BMGs benefits for understanding the unique mechanical properties of the Zr-based BMGs.     

An Overview of Metal–Organic Frameworks for Green Chemical Engineering

Given the current global energy and environmental issues resulting from the fast pace of industrialization, the discovery of new functional materials has become increasingly imperative in order to advance science and technology and address the associated challenges. The boom in metal–organic frameworks (MOFs) and MOF-derived materials in recent years has stimulated profound interest in exploring their structures and applications. The preparation, characterization, and processing of MOF materials are the basis of their full engagement in industrial implementation. With intensive research in these topics, it is time to promote the practical utilization of MOFs on an industrial scale, such as for green chemical engineering, by taking advantage of their superior functions. Many famous MOFs have already demonstrated superiority over traditional materials in solving real-world problems. This review starts with the basic concept of MOF chemistry and ends with a discussion of the industrial production and exploitation of MOFs in several fields. Its goal is to provide a general scope of application to inspire MOF researchers to convert their focus on academic research to one on practical applications. After the obstacles of cost, scale-up preparation, processability, and stability have been overcome, MOFs and MOF-based devices will gradually enter the factory, become a part of our daily lives, and help to create a future based on green production and green living.     

A Rational Reconfiguration of Electrolyte for High-Energy and Long-Life Lithium–Chalcogen Batteries

Lithium–chalcogen batteries are an appealing choice for high-energy-storage technology. However, the traditional battery that employs liquid electrolytes suffers irreversible loss and shuttle of the soluble intermediates. New batteries that adopt Li⁺-conductive polymer electrolytes to mitigate the shuttle problem are hindered by incomplete discharge of sulfur/selenium. To address the trade-off between energy and cycle life, a new electrolyte is proposed that reconciles the merits of liquid and polymer electrolytes while resolving each of their inferiorities. An in situ interfacial polymerization strategy is developed to create a liquid/polymer hybrid electrolyte between a LiPF₆-coated separator and the cathode. A polymer-gel electrolyte in situ formed on the separator shows high Li⁺ transfer number to serve as a chemical barrier against the shuttle effect. Between the gel electrolyte and the cathode surface is a thin gradient solidification layer that enables transformation from gel to liquid so that the liquid electrolyte is maintained inside the cathode for rapid Li⁺ transport and high utilization of active materials. By addressing the dilemma between the shuttle chemistry and incomplete discharge of S/Se, the new electrolyte configuration demonstrates its feasibility to trigger higher capacity retention of the cathodes. As a result, Li–S and Li–Se cells with high energy and long cycle lives are realized, showing promise for practical use.