Azar Alizadeh

General Electric | GE · Global Research Center- Niskayuna

Skin-compatible microfluidic valving systems with on-demand sweat capture are necessary to understand the temporal variation of biomarkers. Here, we demonstrate solution-based electrowetting valves with rapid actuation integrated into a flexible microfluidic sweat collection patch. The valve is produced by inkjet-printing a pair of silver electrode...

Smart clothing with electronic functionality is gaining greater recognition as the next-generation electronics. The integration of electronics into textiles, aided by developments of materials and fabrication technologies, has paved the way to the realization of smart clothing that exhibits diverse electronics functionalities. Lamination of printed...

Scalable printing of conductor and resistor components has revolutionized the field of flexible electronics by enabling a myriad of low cost highly conformable devices. Flexible electronic devices need to exhibit reliable performance under strenuous mechanical deformations to be adopted in applications such as human and asset monitoring. The reliab...

Implementation of wearable sweat sensors for continuous measurement of fluid based biomarkers (including electrolytes, metabolites and proteins) is an attractive alternative to common, yet intrusive and invasive, practices such as urine or blood analysis. Recent years have witnessed several key demonstrations of sweat based electrochemical sensing...

Digitalization and Its Implications for R&D Management is an IRI Research platform established to consider the likely impacts of three distinct sets of digitalization technologies—virtual experimentation and simulation, virtual collaboration, and big data—on R&D in the next five years. In October 2016, as a preliminary step in defining its work, pl...

A method for storing holographic data, said method comprising: step (A) providing an optically transparent substrate comprising a polymer composition and a light absorbing chromophore, said polymer composition comprising a continuous phase and a dispersed phase, said dispersed phase being less than about 200 nm in size; and step (B) irradiating a v...

Surface wettability has emerged as a powerful tool to influence phase change phenomena such as ice formation and steam condensation. Ice mitigation using passive coatings offers tremendous promise; however, there remain several fundamental, durability- and manufacturing-related challenges that need to be addressed to harness the benefits of these c...

Many previous efforts to modify patient monitors for remote or wearable use have suffered from high cost, poor performance, and low medical acceptance. A new technology approach is needed to enable these clinical benefits and to satisfy challenging economic, clinical, and user-acceptance criteria. Here, we present results on our initial efforts aim...

Droplet impact dynamics is vital to the understanding of several phase change and heat transfer phenomena. This work examines the role of substrate elasticity on the spreading and retraction behavior of water droplets impacting flat and textured superhydrophobic substrates. Experiments reveal that droplet retraction on flat surfaces reduces with de...

Ice formation next to solid surfaces is important in many biological, materials, and geological phenomena and how they may impact various technologies. We have used sum frequency generation (SFG) spectroscopy to study the structure of ice as well as the freezing and melting transition temperatures of water in contact with sapphire substrates. We ha...

Droplet impact dynamics determines the performance of surfaces used in many applications such as anti-icing, condensation, boiling and heat transfer. We study impact dynamics of water droplets on surfaces with chemistry/texture ranging from hydrophilic to superhydrophobic and across a temperature range spanning below freezing to near boiling condit...

Prevention of ice accretion and adhesion on surfaces is relevant to many applications, leading to improved operation safety, increased energy efficiency, and cost reduction. Development of passive nonicing coatings is highly desirable, since current antiicing strategies are energy and cost intensive. Superhydrophobicity has been proposed as a lead...

Ice accretion on surfaces of aircrafts, wind turbine blades, oil and gas rigs and heat exchangers, to name a few examples, presents long recognized problems with respect to efficiency and cost of operation. For instance, significant ice accretion on critical surfaces of an aircraft will cause problems during lift off (and will change the aerodynami...

The control of ice formation next to solid surfaces is important in many technological applications such as de-icing for aircrafts and generation of power using wind turbines. We have studied the water-ice transition next to sapphire surface to understand the freezing transition and nucleation of ice. The infrared-visible sum frequency generation s...

Semi-crystalline block copolymers are well known to exhibit confined crystallization and/or melting phase transitions in sub-50 nm domains. Confined crystallization within these nano-domains is favored under the following conditions: 1) the crystallizable block forms discrete spherical or cylindrical domains; 2) the glass transition temperature of...

We have applied density-functional theory (DFT) based calculations to investigate the size and strain effects on the electronic properties, such as band structures, energy gaps, and effective masses of the electron and the hole, in Si nanowires along the <110> direction with diameters up to 5 nm. Under uniaxial strain, we find the band gap varies w...

We study the adhesion of liquid droplets to rough surfaces, focusing on how adhesion changes with surface chemistry and roughness. For hydrophobic surfaces (equilibrium contact angle θ(e)>90°), although increasing surface roughness augments apparent contact angle, it does not necessarily always reduce adhesion. In a domain defined by roughness and...

We report on measurements of the infrared photo-response of InAs-based p-i-n diodes in the spectral region above 1.8 ¿m. These photodiodes were fabricated from arrays of InAs quantum dots grown in nano-patterned template structures using a combination of block copolymer lithography and molecular beam epitaxy. The devices studied were comprised of...

A two-day workshop designed to expose 11th and 12th grade students to industrial applications of Materials Science and Nanotechnology is described. This workshop has been taught to seven 32-student cohorts since 2004 at the Materials Science and Nanotechnology Summer High School program at Columbia University. During the first day, teams of five to...

We report on selective area growth of InAs quantum dots on GaAs substrates patterned with a hexagonal array of 20 nm pores using block copolymer lithography. We discuss the mechanisms of growth, highlighting the variation in the resulting morphology as a function of nucleation enhancing AlGaAs layers. We also evaluate the optoelectronic performance...

We report on selective area growth of InAs and GaAs quantum dots (QDs) on GaAs through ∼20 nm SiO ₂ windows prepared by block copolymer lithography. We discuss the mechanisms of growth through these masks, highlighting the variation of the resulting morphology (dot size, spacing, uniformity, and areal density) as a function of growth par...

This chapter reviews the multiscale modeling of the synthesis of quantum nanodots and their arrays. Reducing the sizes of crystals to the nanometer range strongly affects their optical and electrical properties. This effect is attributed to the changes in the density of states of electrons as a function of the dot size—that is, a quantum size effec...

We have studied the band-gap variation and stability energy in silicon carbide (SiC) nanoclusters of different polytypes using density functional theory (DFT) based on a gradient-corrected approximation. We have obtained a series of spherical SiC nanoclusters with dimensions up to 2 nm from bulk 2H, 3C, and 4H polytype crystals. All clusters with d...

First-principles density functional calculations were performed to study strain effects on the energy gaps in silicon nanoclusters with diameter ranging from 0.6 to 2 nm. Hydrostatic and non-hydrostatic strains have been found to affect the energy gaps differently. For the same strain energy density, non-hydrostatic strain leads to a significantly...

Block copolymer lithography offers a promising route for fabricating wide band gap semiconductor quantum dots. A PS-PMMA block copolymer is self-assembled over a random copolymer brush to allow for perpendicular orientation of PMMA cylinders. The substrate consists of GaAs, SiO2 and the brush layer. The block copolymer pattern is transferred to the...

of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

Density functional calculations on silicon clusters show that strain effects on the band gap display qualitatively new trends for dots smaller than ∼2nm. While the bulk indirect band gap increases linearly with increasing strain, this trend is reversed for small clusters (⩽1nm). In the intermediate 1–2nm size range, strain appears to have almost no...

The size dependence of energy gap is perhaps the most remarkable aspect of quantum confinements in low dimensional systems. Numerous models have been proposed to describe the quantum confined electronic states in Si, CdSe, etc, providing a precise description of the bandgap as a function of nano-crystal dimensions. Recently, ab-initio studies of en...

Formation of highly ordered and morphologically controlled nanoparticle/polymeric assemblies is highly desirable in a variety of applications including optoelectronics, sensing, photonics and catalysis. Structure-guiding polymer matrices, such as block copolymers, have demonstrated to be an effective means for controlling the composite morphology a...

We report on the selective-area heteroepitaxy and facet evolution of submicron GaN islands on GaN-sapphire, AlN-sapphire, and bare sapphire substrates. It is shown that strain due to the lattice mismatch between GaN and the underlying substrate has a significant influence on the final morphology and faceting of submicron islands. Under identical me...

It is well known that nanoscale Si clusters are photo luminescent. In parallel, industry routinely exploits the dramatic strain dependence of the band gap of bulk Si for electronics applications. We have discovered, using density functional calculations that the combined role of finite size and strain leads to previously unanticipated effects on th...

The self assembly of a nonporous nanostructured silicon carbonitride ceramic precursor into an ordered structure using an amphiphilic block copolymer as template. The polysilazane (PSZ) and polybutadiene-block-poly(ethylene oxide) (PB-b-PEO) was used as the ceramic precursor and block copolymer, respectively. This ordered nanostructure is stabilize...

We present new scaling laws that govern coupled mechanical deformation and opto-electronic properties (band gap) of quantum dots. Our theoretical work on quantum dots, confirmed via electronic structure calculation based on density functional theory indicates that novel size effects in band gap (above and beyond the well studied quantum confinement...

Dynamic control of internarticle coupling within a single material comprising gold nanoparticles and poly(N-isopropylacrylamide) has been developed. Core/shell particles with defined shell thicknesses are the building blocks for preparing films of sufficiently high gold nanoparticle density necessary for achieving reversible switching of several op...

Many natural ceramic structures, such as nacre, exhibit fracture toughness values much higher than those of the constituent ceramic material. There are many factors contributing to this enhancement, with the ordered microstructure playing a critical role. A key challenge in making bio-inspired, structural ceramics based on these observations is to...

Multiscale simulations are used to bridge the surfactant templated assembly of individual approximately 1-10 nm cobalt dots, to their ordering into supramolecular arrays. Potential energy surfaces derived from ab initio calculations are input to lattice Monte Carlo simulations at atomic scales. By this process we quantitatively reproduce the experi...

Much work has been done in the approximation of the stress state of microelectronics interconnects-on-chips. The thermally induced stresses in passivated interconnects are of interest as they are used as input in interconnect reliability failure models (stress-driven void growth, electromigration driven void growth). The typically used classical co...

In this two-pronged work we report a a study of defect nucleation in three-dimensional confined nanoislands and b a surface-elasticity induced size effect in the optoelectronic properties of embedded and templated semiconducting nanostructures. Several key features in the design of nanostructure templates are analyzed and dislocation free contour m...

Glass transition and melting temperatures of supported and freestanding ultrathin polymer films have been extensively investigated in the literature using techniques such as ellipsometry, Brillioun scattering, and AFM. Even though these techniques allow for the determination of the location (temperature) of phase transition, they do not provide a d...

High resolution imaging of nanoengineered polymer systems is critical for advanced technology programs at GE. We will discuss scanning probe microscopy (SPM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) of self-assembled block co-polymers and polymer nanocomposites. SEM and TEM with energy-filtered imaging of cons...

Despite the immense technological significance of phase transitions and thermodynamic properties of polymer thin films and other nano-structures, several fundamental issues remain unresolved. This is partly due to insufficient sensitivity and high thermal time constants of conventional thermal characterization techniques, e.g. differential scanning...

The dielectric behavior of a family of block copolymers based on poly(butylene terephthalate) (PBT) and aliphatic polycarbonate (PC), with the composition of PBT varying from 100 wt.-% to 40 wt.-%, has been investigated by broad-band dielectric spectroscopy in the frequency range from 10–1 to 109 Hz. At temperatures above the glass transition, the...

In this paper, we report differential scanning calorimetry studies of the temperature and molar mass dependences for the primary and secondary crystallization behavior of bisphenol A polycarbonate (BAPC). The molar mass dependence of the crystallization rate is found to be much stronger during primary than during secondary crystallization, confirmi...

Differential scanning calorimetry studies of the heating rate dependence of the multiple melting behavior of semicrystalline bisphenol A-polycarbonate (BAPC) are presented for different molar masses. In all cases, heating traces exhibit, in addition to the high temperature endothermic transition, a low endotherm located slightly above the crystalli...

The secondary crystallization and its influence on the glass transition are studied as a function of crystallization temperature and time by differential scanning calorimetry for PEEK. The multiple melting behavior resulting from isothermal annealing from the glass or crystallization from the melt is discussed in the context of models considering e...

In recent investigations, the multiple melting behavior of many semicrystalline samples such as ethylene/alpha-olefin copolymers, bisphenol-A polycarbonate, PEEK, PET, PBT, nylon-6 and it-PS, subjected to a variety of secondary crystallization experiments, has been thoroughly studied. For all these samples, the multiple melting behavior, usually, r...

Studies of the crystallization, melting, and morphology of random ethylene/1-octene copolymers by a combination of differential scanning calorimetry and atomic force microscopy are presented. Two different crystallization mechanisms prevalent in separate temperature ranges are inferred from the effect of cooling rate on the temperature dependence o...

The phase behaviour of a series of poly(ester-carbonate) block copolymers based on poly(butylene terephthalate) (PBT) and aliphatic poly(carbonate) (PC) has been investigated as a function of ester/carbonate composition using calorimetry and X-ray methods. The ability of PBT segments to crystallize and the low value of the Flory-Huggins interaction...

Previous studies using small angle X-ray scattering have suggested that crystals of linear polyethylene exhibit a reversible process of thickening when cooled below their crystallization temperature. The implication of their study is that the degree of crystallinity measured at room temperature should be significantly higher than that measured at t...

The melting behavior of ethylene/a-olefin copolymers of well controlled microstructure and narrow molecular weight distribution will be discussed. Specifically, we will report results of investigations of the effect of crystallization temperature and time on the multiple melting behavior of ethylene copolymers of various contents in butene, pentene...

There is a growing consensus in the technical community regarding the enormous application potential of wide bandgap (WBG) semiconductor nanostructures, ranging from optoelectronics, to field emitters and harsh environment sensors. Templated growth method appears as one of the most promising avenues for fabrication of tailored highly monodisperse W...

When semicrystalline polymers of low to moderate crystallinity (i.e. less than 75-80 crystallization temperature, their subsequent heating in a differential scanning calorimeter generally leads to the observation of a multiple endothermic behavior. Interestingly, the characteristics of this multiple melting behavior appear to be universal. For exam...