Mesa+ Meeting

1Advanced materials & devices, chaired by dr.ir. Floris Zwanenburg

2Fluidics & microsystems, chaired by dr.ir. Mathieu Odijk

3Photonics & (bio)systems, chaired by dr.ir. Annemarie Huijser

4Soft matter & devices, chaired by dr.ir. Wiebe de Vos

Advanced Materials & devices

Chair: Floris Zwanenburg (NanoElectronics)

INTRODUCTION

This parallel session focuses on the electronic properties of advanced nanoscale materials, varying from 2-dimensional materials such as silicene and MoS₂ to superconducting Nb islands on Au. The presenters use different techniques to study their materials, in particular low-temperature electron transport measurements, in device and STM configuration and DFT calculations.

PROGRAM

ABSTRACTS

Critical behavior at a dynamic vortex insulator-to-metal transition – Nicola Poccia (Interfaces and Correlated Electron Systems)

Superconducting vortices offer a unique tunable laboratory for studying classical critical dynamics. However, phase transitions and criticality far from equilibrium are less well understood respect their equilibrium counterpart. Using an array of superconducting islands placed on a normal metal film, we observed a vortex insulator–vortex metal transition driven by the applied electric current. Our findings offer a comprehensive description of dynamic critical behavior and establish a connection between equilibrium and non-equilibrium phase transitions.

Group IV-materials beyond graphene: the growth of silicene studied with by low energy electron microscopy – Adil Acun (Physics of Interfaces and Nanomaterials)

We have studied the formation and stability of silicene layers on Ag(111) by using low energy electron microscopy. Theoretical calculations show skepticism towards the stability of the graphene-like analog of silicon. We report that silicene layers are intrinsically unstable against the formation of “diamond-like” hybridized silicon structures. Thermal Si adatoms created by the silicene layer trigger the irreversible formation of the “sp3-like” hybridized silicon structure. The same instability hinders the formation of a fully closed silicene layer, making future large-scale fabrication promises of silicene layers on Ag-substrates unlikely.

Silicene on h-BN terminated surfaces – Frank Wiggers (NanoElectronics)  
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Tuning the Schottky barrier heights at MX2/metal contacts – Mojtaba Farmanbar (Computational Materials Science) 

The nature of the Schottky barrier at metal contacts with the two-dimensional semiconductor MX2 is controversial. Using first-principles DFT calculations we show that, one could control the Schottky barrier height at the interface by inserting a boron nitride (BN) monolayer between the metal surface and the MX2 layer. The BN layer disrupts the interaction between the metal surface and the MX2 layer and changes the metal work function, thereby enable us to reach a zero barrier for electrons or holes.

Fluidics & microsystems

Chair: Mathieu Odijk (BIOS lab on chip group)

INTRODUCTION

PROGRAM

ABSTRACTS

Performance study of pervaporation in a microfluidic system for the removal of acetone from water - Yali Zhang (Soft Matter, Fluidics and Interfaces group)

We aim to conduct a performance study for the removal of acetone from water using a continuous micro-pervaporation system. High acetone removal efficiency of 84% is achieved for just 4 minutes residence time at room temperature. We have derived a design criterion based on the intrinsic system parameters to engineer the pervaporation system for both micro- and macro-scales.

pH gradient chromatofocusing on a chip – Hoon Suk Rho (Mesoscale Chemical Systems)

We have developed a novel microfluidic platform for pH-gradient chromatofocusing of proteins by adapting 16 parallel micro-mixers, a micro-column, and a multiplexer. The creation of 16 non-linear gradients and the generation of a solid-phase micro-column have been achieved for the realization of anion exchange chromatography on a single chip. With the device we demonstrated the separation of a protein mixture of R-phycoerythrin and FITC-BSA based on pH-gradient chromatofocusing. We believe that the fully automated and integrated microfluidic platform for high-throughput protein screening could be considered as a promising approach for fast biopharmaceutical process development.

Microreactor with integrated boron doped diamond electrodes for electrochemical protein cleavage and drug screening – Floris van den Brink (BIOS Lab on a Chip Group)

Electrochemical cells on chip have shown potential for use in both proteomics studies and drug screening, and in this presentation we highlight these areas of application. With our latest developments we aim to exploit the benefits of boron doped diamond as a novel electrode material to conduct tyrosine- and tryptophan-specific electrochemical protein cleavage. In addition, we mimic phase I drug metabolism on chip and we were able to detect short-lived and reactive metabolites, demonstrating a valuable assay for early drug discovery processes.

Fluidic force microscopy for single cell analysis – Jos Quist (NanoIonics)

A force microscope with integrated microfluidic probe was used to study the waterborne pathogen Cryptosporidium with a throughput of >50 cells/hr. Whereas conventional microscopy techniques cannot discern non-viable pathogens from viable ones, force measurements revealed a loss of elastic anisotropy after heat treatment. Currently, we are extending the platform with a micro/nanofluidic chip for subcellular sampling.

Photonics & (bio)systems

Chair: Annemarie Huijser (Optical Sciences)

INTRODUCTION

This parallel session focuses on advanced periodic nanostructures ranging from photonic crystals to multilayer mirrors and plasmonic antennas. The speakers use advanced optical techniques to characterize these nanostructures, including near-field imaging and pulse shaping.

PROGRAM

ABSTRACTS

Optical correlations in 2D and 3D photonic crystals with weak and strong disorder –

Femi Ojambati (Complex Photonic Systems)

Photonic crystals are periodic structures with a periodicity comparable to the wavelength. In an ideal (perfect and infinite) photonic crystal, Bloch modes only propagate. However, a real photonic crystal has structural imperfections in size and position. The imperfections in a real crystal results into scattering, and light transport deviates from that of a perfect crystal. In this presentation, I will present the experimental results of investigating light transport in a real crystal by measuring the reflected intensity from the photonic crystal. We use autocorrelation and cross correlation of the reflected intensity to resolve the periodic structure of the crystal. We qualitatively compare the amount of disorder in one part of the crystal to another part. Furthermore, we will see that there are correlations in the reflected intensity from the crystal.

High reflectance La/B based multilayer mirrors for 6 nm wavelength – Dmitry Kuznetsov (Industrial Focus Group XUV Optics)

For future photolithography processes, the wavelength of 6 nm is candidate for high resolution imaging. The perspective of this chip fabrication technique however, will depend essentially on the performance of multilayer reflective mirrors, which will need to be based on La/B multilayer reflectors. One of the issues is the formation of LaxBy compounds at the interfaces, which decreases the optical contrast and therefore reduces the reflectivity. To prevent such chemical interaction, passivation of the La layers by nitrogen has been investigated. We successfully synthesized LaN layers that resulted in a new world record reflectivity of 64.1% at ~6.7 nm at near normal incidence. This significantly reduces the gap to the target of 70% reflectivity, desired for a possible next generation of lithography.

 A phased antenna array for surface plasmons – Dirk Jan Dikken (Optical Sciences)

Surface plasmon polaritons are electromagnetic waves that propagate tightly bound to metal surfaces. The concentration of the electromagnetic field at the surface as well as the short wavelength of surface plasmons enable sensitive detection methods and miniaturization of optics. We present an antenna array for plasmons in which the phase of each antenna element is fully and independently controlled. Individual holes in a thick gold film act as dipolar emitters of surface plasmon polaritons whose phase is controlled individually using a digital spatial light modulator. We experimentally show, using a phase sensitive near-field microscope, that this allows accurate directional emission of surface waves. Our method presents a compact and flexible way to dynamically shape the propagation of plasmons and holds promise for nanophotonic applications employing

propagating surface plasmons.

Integrated Microwave Photonics Filters – Caterina Taddei (Laser Physics and Nonlinear Optics)

Microwave Photonics (MWP) is a promising field aiming at optical processing of electronic (GHz) data, such as complex filtering, beyond what is possible with conventional, all-electronic methods. Despite the increasing interest in MWP, current approaches based on standard technology such as fibers are limited by high instability and bulkiness. Here we focus on Integrated MWP filters fabricated using low-loss, high-index contrast Si₃N₄/SiO₂ waveguide technology. As typical examples we present temporal differentiation, channel selection in satellite communication systems and true time delay beamsteering of antenna arrays.

Soft Matter & Devices

Chair: Dr. Wiebe M. de Vos

INTRODUCTION

Soft Matter comprises a wide variety of states that are easily deformable, including: fluids, polymers, colloids, and gels. This gives Soft Matter peculiar properties, such as various types of responsive behaviours and the ability to self-assemble into complex structures. Within MESA+ many groups research Soft Matter fundamentals or utilize these materials as a basis for their approaches to nanotechnology.

The Soft Matter and Devices Focus Area aims to bring together the excellent work performed within MESA+, where Nanotechnology and Devices are based on Soft Matter. This focus area is coupled to the monthly Soft Matter+ colloquium series, as organized by team of Postdocs and Tenure Trackers from various research groups. This session will show a variety of very promising and recent work at MESA+ regarding Soft Matter and Devices.

PROGRAM

ABSTRACTS

To stick or not to stick – Hubert Gojzewski (Materials Science and Technology of Polymers)

Most of AFM based Single Molecule Force Spectroscopy studies are performed at perpendicular desorption configuration, i.e. molecule stretching direction forms a right angle with the substrate.  The desorbed section of chains, however, makes a finite angle with the substrate, and can result in different pulling force (critical force vs. angle). Therefore, the pull angle must be known. We show our first attempt to face this problem experimentally with AFM for a single polymer chain. 

Hyper-cross-linked hybrid thin films – Evelien Maaskant (Inorganic Membranes)

Hyper-cross-linked networks consisting of homogeneously distributed covalently bonded inorganic or biological and organic precursors are anticipated to show remarkable characteristics that may be distinct from those of the individual constituents. Fabrication of these networks by interfacial polymerisation allows the formation of smooth, ultra-thin, and defect free thin films that can for instance be used as membranes. During this talk, the preparation and performance of these hybrid membranes will be discussed.

Stability Limits of Capillary Bridges – Rielle de Ruiter (Physics of Fluids)

The equilibrium shape of a drop in contact with solid surfaces can undergo continuous or discontinuous transitions upon changes in either drop volume or surface energies. In many instances, such transitions involve the motion of the three-phase contact line and are thus sensitive to contact angle hysteresis. Using a combination of electrowetting-based experiments and numerical calculations, we demonstrate for a generic sphere-plate confinement geometry how contact angle hysteresis affects the mechanical stability of competing axisymmetric and nonaxisymmetric drop conformations and qualitatively changes the character of transitions between them.

Towards macromolecular nanoparticles using a virus-based scaffold – Stan Maassen (Biomolecular NanoTechnology)

Macromolecular nanoparticles find different applications in, for example, drug delivery, imaging and coatings. Although a variety of polymerization protocols have been reported, it remains challenging to synthesize them with precise control over their size and dispersity. Here we employ the protein cage of the Cowpea Chlorotic Mottle Virus, which is highly defined, as a scaffold to achieve such control in the preparation of macromolecular nanoparticles.