Large Scale Integration of Functional Radio-Frequency Flexible MEMS under Large Mechanical Strain

A versatile industrial recipe of transferring nitride microelectronic components such as micro-electromechanical systems (MEMS) onto flexible and stretchable substrates is demonstrated. This method bypasses difficulties of temperature-related processing, and is applicable to large-scale and mass production. The technological process of fabrication is presented along with its underlying structural and radio-frequency characterizations. In particular, the Raman strain shifts of aluminum nitride (AlN) thin films are determined for uniaxial and biaxial mechanical deformations. The transferring process onto polymer is also demonstrated by an adhesive bonding of AlN-based MEMS onto a 200 mm silicon (Si) wafer. The devices microstructure is assessed using X-ray before and after transferring, as well as their electrical radio-frequency (RF) features when on Si and polymer substrates. Then, RF measurements are also performed on the transferred and flexible devices; some in their relaxed states, and others in an in situ manner under an increasing macroscopic strain. It is shown that bulk acoustic wave resonator MEMS are fully functional even under 12% uniaxial stretching of the substrate.     

Flexible Oxide Thin Film Transistors,Memristors, and Their Integration

Flexible electronics have seen extensive research over the past years due to their potential stretchability and adaptability to non-flat surfaces. They are key to realizing low-power sensors and circuits for wearable electronics and Internet of Things (IoT) applications. Semiconducting metal-oxides are a prime candidate for implementing flexible electronics as their conformal deposition methods lend themselves to the idiosyncrasies of non-rigid substrates. They are also a major component for the development of resistive memories (memristors) and as such their monolithic integration with thin film electronics has the potential to lead to novel all-metal-oxide devices combining memory and computing on a single node. This review focuses on exploring the recent advances across all these fronts starting from types of suitable substrates and their mechanical properties, different types of fabrication methods for thin film transistors and memristors applicable to flexible substrates (vacuum- or solution-based), applications and comparison with rigid substrates while additionally delving into matters associated with their monolithic integration.     

Synthesis of Free-Standing Crystalline Barium Titanate Films at Vapor/Liquid or Liquid/Liquid Interface

Synthesis of free-standing crystalline barium titanate (BaTiO₃) films at vapor/liquid or liquid/liquid interface at room temperature has been investigated. High concentration Ba, Ti alkoxides precursor solution (1.2 mol/l) or pre-hydrolyzed precursor solutions by water vapor in a H₂O/Ba molar ratio of 0 to 6 were used as dropping solutions at the interfaces. Transparent gel films were formed when partially hydrolyzed precursors (H₂O/Ba = 2 to 3) were spread out on a N₂/liquid paraffin interface. The films shrank from syneresis and vaporization of the solvent during aging at room temperature. As a result, free-standing transparent films with a thickness of around 1 m and little stoichiometric deviation were obtained by separation from the liquid surface and rinse by hexane. The films consisted of crystalline BaTiO₃ particles of less than a few nanometers. Nanostructured dense BaTiO₃ free-standing films with a grain size less than 100 nm were obtained at 1030°C.     

Preparation of a novel biodegradable film by co-fermentation of straw and shrimp shell with Aureobasidium pullulans and Photobacterium sp. LYM-1

The green and high-value recycling of shrimp shell and straw remains a worldwide problem. This study aimed to investigate the potential utilization of a fermentation broth (FB) which contains shrimp shell and straw as a new source for preparation of biodegradable films. Aureobasidium pullulans and Photobacterium sp. LYM-1 were used in the fermentation. The cellulase activity was 115.92 U/mL and chitinase activity was 17.89 U/mL in FB. The polysaccharides concentration in FB was 1.05 mg/mL after 7 days of fermentation. An eco-friendly PVA-reinforced FB biodegradable film (FBBF) was successfully prepared and the effect of different plasticizers and surfactants on the mechanical, structural, and impermeability properties of the film was determined. The formation of new bonds between PVA and FB was proved by FTIR spectroscopy. The FBBF containing 0.25 % (w/v) glycerol and 0.01 % (v/v) tween-20 showed better strength properties. Elongation and water-swelling properties were highly improved by adding 0.2 % (m/v) citric acid. According to FE-SEM images, the smooth and tight surface of citric acid added FBBF was observed. Interestingly, the FBBF film showed good heat/moisture capacity, antifungal, and degradation properties. This report reveals a new green, and high-value recycling of straw and shrimp shell by the co-fermentation with A. pullulans and Photobacterium sp. LYM-1. It is also a novel way for the preparation of biodegradable film.     

Hydrogenation of α,β-unsaturated substrates by tris(2-phridyl)amine (tpN) or tris(2-pyridyl)phosphine (tpP)/[Ir(COE)2Cl]2 catalyst systems

This work describes the homogeneous hydrogenation of different α,β-unsaturated substrates by using as catalyst systems the complex [Ir(COE)₂Cl]₂ stabilized by tris(2-pyridyl)amine (tpN) or tris(2-pyridyl)phosphine (tpP) formed in situ under the following reaction conditions: pH₂ = 34 atm; T=373 K; substrate/catalyst ratio = 100, [ligand]/[metal]: 2,1; toluene (50 mL); R.P.M.: 430; t = 6 h. The activities varies from low to moderate range, where both ligands proved to be catalyst systems able to hydrogenate C=C and C=O bonds.     

Kinetics of enzymatic hydrolysis of sodium carboxymethylcellulose with different degrees of polymerization by cellulase

The reaction cellulase (EC 3.2.1.4)—sodium carboxymethylcellulose (Na-CMC) with different degrees of polymerization (n=140, 640 and 900) was investigated by the use of a modifiedMichaelis-Menten equation, valid for enzymatic hydrolysis of linear homopolymers. TheMichaelis-Menten constant [Km (M)=6.31·10^–2mol/dm³] and the reaction rate constant (k ₊₂=4.07·10^–6s^–1), which correspond to the enzymatic hydrolysis of a single bond in the homopolymer substrates are determined. The free energy ( =101 kJ/mol), which corresponds to the degradation and formation of a single bond in the enzyme—polymer substrate is also estimated. This energy expressed in electronvolt units is =1.39 eV. The ratio between the effective cross section of the reactive substrate bond and the active enzyme center is =1.22.

---

Kinetik der enzymkatalysierten Hydrolyse von Natriumcarboxymethylcellulose mit verschiedenem Polymerisationsgrad durch Cellulase

Zusammenfassung Die modifizierte Gleichung nachMichaelis-Menten wird bei der durch Cellulase (EC 3.2.1.4) katalysierten hydrolytischen Spaltung von Natriumcarboxy-methylcellulose (Na-CMC) verschiedenen Polymerisationsgrades (n=140, 640 und 900) angewandt. Es wurde dieMichaelis-Menten-Konstante [Km (M)=6.31·10^–2mol/dm³] und die Reaktionsgeschwindigkeitskonstante (k ₊₂=4.07·10^–6s^–1), die der enzymatischen Hydrolyse einer Einfachbindung im homopolymeren Substrat entspricht, berechnet. Die freie Energie ( =101 kJ/mol), die dem Abbau und der Bildung einer Einfachbindung im Enzym—Polymer-Substrat entspricht, wurde bestimmt. Diese Energie — ausgedrückt in Elektronvolt-Einheiten — beträgt =1.39 eV. Das Verhältnis zwischen den effektiven Querschnitten der reaktiven Substratbindung ( _S ) und des aktiven Enzym-Zentrums ( _E ) beträgt =1.22.

     

Recent advancement and development of chitin and chitosan-based nanocomposite for drug delivery: Critical approach to clinical research

This review depicts the exposure of chitin and chitosan base multifunctional nanomaterial composites for promising applications in field of biomedical science structure, synthesis as well as potential application from a colossal angle. We elaborated critically each of the chitin and chitosan base nanomaterial with its potential application toward biomedical science. For different biomedical applications it use in form of hydrogels, microsphere, nanoparticles, aerogels, microsphere and in form of scaffold. Due to this it had been blended with different polymer such as starch, cellulose, alginate, lipid, hyaluronic acid, polyvinyl alcohol and caboxymethyl cellulose. In this review article, a comprehensive overview of combination of chitin and chitosan base nanomaterial with natural as well as synthetic polymers and their biomedical applications in biomedical field involving drug delivery system all the technical scientific issues have been addressed; highlighting the recent advancements.     

Substrate-induced anisotropy of c-axis textured NaxCoO2 thin films

Na_xCoO₂ [x = 0.51, 0.54, and 0.59] thin films have been grown on SrTiO₃ (100)-oriented single crystals with a 5° vicinal cut towards [010] by pulsed laser deposition. We analysed the films by X-ray diffractometry, atomic force microscopy (AFM), and dc-transport measurements. X-ray diffraction patterns of the films show single phase and c-axis textured growth with the film plane closely aligned to the [001]-direction of 5° miscut SrTiO₃ (001) substrates. In addition to the structural analysis of these films we performed transport measurements along and perpendicular to the substrate tilt direction and determined the resistivity anisotropy as a function of temperature. The results enable the development of a strategy for the fabrication of Na_xCoO₂ based thermoelectric thin film devices.     

High-temperature growth of very high germanium content SiGe virtual substrates

We have first of all studied (in reduced pressure–chemical vapour deposition) the high-temperature growth kinetics of SiGe in the 0–100% Ge concentration range. We have then grown very high Ge content (55–100%) SiGe virtual substrates at 850 °C. We have focused on the impact of the final Ge concentration on the SiGe virtual substrates’ structural properties. Polished Si_0.5Ge_0.5 virtual substrates were used as templates for the growth of the high Ge concentration part of such stacks, in order to minimize the severe surface roughening occurring when ramping up the Ge concentration. The macroscopic degree of strain relaxation increases from 99% up to values close to 104% as the Ge concentration of our SiGe virtual substrates increases from 50% up to 100% (discrepancies in-between the thermal expansion coefficients of Si and SiGe). The surface root mean square roughness increases when the Ge concentration increases, reaching values close to 20 nm for 100% of Ge. Finally, the field (the pile-up) threading dislocations density (TDD) decreases as the Ge concentration increases, from 4×10⁵ cm⁻² (1–2×10⁵ cm⁻²) for [Ge]=50% down to slightly more than 1×10⁵ cm⁻² (a few 10⁴ cm⁻²) for [Ge]=88%. For [Ge]=100%, the field TDD is of the order of 3×10⁶ cm⁻², however.     

Fe3O4@Au纳米星颗粒作为循环SERS基底用于农药残留物的检测

本文首先采用共沉淀的方法制备了Fe3O4纳米颗粒,随后经柠檬酸钠和对苯二酚还原氯金酸的方法在Fe3O4纳米颗粒的表面生成刺状Au纳米结构,进而获得Fe3O4@Au纳米星颗粒。该Fe3O4@Au纳米星颗粒作为SERS基底,用作农药残留物福美双和敌瘟磷的检测。由于高密度的Au纳米结构的尖端效应,该基底显示出高敏感的SERS活性。最后利用Fe3O4纳米颗粒的磁性,将其用于循环SERS测试,研究了其循环使用特性。