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Dive into the research topics where Michael Stenbæk Schmidt is active.

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Featured researches published by Michael Stenbæk Schmidt.


Advanced Materials | 2012

Large Area Fabrication of Leaning Silicon Nanopillars for Surface Enhanced Raman Spectroscopy

Michael Stenbæk Schmidt; Jörg Hübner; Anja Boisen

Using a simple two step fabrication process substrates with a large and uniform Raman enhancement, based on flexible free standing nanopillars can be manufactured over large areas using readily available silicon processing equipment.


Nano Letters | 2013

Enhanced Light–Matter Interactions in Graphene-Covered Gold Nanovoid Arrays

Xiaolong Zhu; Lei Shi; Michael Stenbæk Schmidt; Anja Boisen; Ole Hansen; Jian Zi; Sanshui Xiao; N. Asger Mortensen

The combination of graphene with noble-metal nanostructures is currently being explored for strong light-graphene interactions enhanced by plasmons. We introduce a novel hybrid graphene-metal system for studying light-matter interactions with gold-void nanostructures exhibiting resonances in the visible range. Enhanced coupling of graphene to the plasmon modes of the nanovoid arrays results in significant frequency shifts of the underlying plasmon resonances, enabling 30% enhanced absolute light absorption by adding a monolayer graphene and up to 700-fold enhancement of the Raman response of the graphene. These new perspectives enable us to verify the presence of graphene on gold-void arrays, and the enhancement even allows us to accurately quantify the number of layers. Experimental observations are further supported by numerical simulations and perturbation-theory analysis. The graphene gold-void platform is beneficial for sensing of molecules and placing Rhodamine 6G (R6G) dye molecules on top of the graphene; we observe a strong enhancement of the R6G Raman fingerprints. These results pave the way toward advanced substrates for surface-enhanced Raman scattering (SERS) with potential for unambiguous single-molecule detection on the atomically well-defined layer of graphene.


ACS Nano | 2013

Surface-enhanced Raman spectroscopy based quantitative bioassay on aptamer-functionalized nanopillars using large-area Raman mapping.

Jaeyoung Yang; Mirkó Palla; Filippo Bosco; Tomas Rindzevicius; Tommy Sonne Alstrøm; Michael Stenbæk Schmidt; Anja Boisen; Jingyue Ju; Qiao Lin

Surface-enhanced Raman spectroscopy (SERS) has been used in a variety of biological applications due to its high sensitivity and specificity. Here, we report a SERS-based biosensing approach for quantitative detection of biomolecules. A SERS substrate bearing gold-decorated silicon nanopillars is functionalized with aptamers for sensitive and specific detection of target molecules. In this study, TAMRA-labeled vasopressin molecules in the picomolar regime (1 pM to 1 nM) are specifically captured by aptamers on the nanostructured SERS substrate and monitored by using an automated SERS signal mapping technique. From the experimental results, we show concentration-dependent SERS responses in the picomolar range by integrating SERS signal intensities over a scanning area. It is also noted that our signal mapping approach significantly improves statistical reproducibility and accounts for spot-to-spot variation in conventional SERS quantification. Furthermore, we have developed an analytical model capable of predicting experimental intensity distributions on the substrates for reliable quantification of biomolecules. Lastly, we have calculated the minimum needed area of Raman mapping for efficient and reliable analysis of each measurement. Combining our SERS mapping analysis with an aptamer-functionalized nanopillar substrate is found to be extremely efficient for detection of low-abundance biomolecules.


ACS Nano | 2012

Biomineralization Mechanism of Gold by Zygomycete Fungi Rhizopous oryzae

Sujoy K. Das; Jinni Liang; Michael Stenbæk Schmidt; Fathima Laffir; Enrico Marsili

In recent years, there has been significant progress in the biological synthesis of nanomaterials. However, the molecular mechanism of gold biomineralization in microorganisms of industrial relevance remains largely unexplored. Here we describe the biosynthesis mechanism of gold nanoparticles (AuNPs) in the fungus Rhizopus oryzae . Reduction of AuCl(4)(-) [Au(III)] to nanoparticulate Au(0) (AuNPs) occurs in both the cell wall and cytoplasmic region of R. oryzae . The average size of the as-synthesized AuNPs is ~15 nm. The biomineralization occurs through adsorption, initial reduction to Au(I), followed by complexation [Au(I) complexes], and final reduction to Au(0). Subtoxic concentrations (up to 130 μM) of AuCl(4)(-) in the growth medium increase growth of R. oryzae and induce two stress response proteins while simultaneously down-regulating two other proteins. The induction increases mycelial growth, protein yield, and AuNP biosynthesis. At higher Au(III) concentrations (>130 μM), both mycelial and protein yield decrease and damages to the cellular ultrastructure are observed, likely due to the toxic effect of Au(III). Protein profile analysis also confirms the gold toxicity on R. oryzae at high concentrations. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis shows that two proteins of 45 and 42 kDa participate in gold reduction, while an 80 kDa protein serves as a capping agent in AuNP biosynthesis.


PLOS ONE | 2013

Mapping the Complex Morphology of Cell Interactions with Nanowire Substrates Using FIB-SEM

Rafal Wierzbicki; Carsten Købler; Mikkel Jensen; Joanna M. Łopacińska; Michael Stenbæk Schmidt; Maciej Skolimowski; Fabien Abeille; Klaus Qvortrup; Kristian Mølhave

Using high resolution focused ion beam scanning electron microscopy (FIB-SEM) we study the details of cell-nanostructure interactions using serial block face imaging. 3T3 Fibroblast cellular monolayers are cultured on flat glass as a control surface and on two types of nanostructured scaffold substrates made from silicon black (Nanograss) with low- and high nanowire density. After culturing for 72 hours the cells were fixed, heavy metal stained, embedded in resin, and processed with FIB-SEM block face imaging without removing the substrate. The sample preparation procedure, image acquisition and image post-processing were specifically optimised for cellular monolayers cultured on nanostructured substrates. Cells display a wide range of interactions with the nanostructures depending on the surface morphology, but also greatly varying from one cell to another on the same substrate, illustrating a wide phenotypic variability. Depending on the substrate and cell, we observe that cells could for instance: break the nanowires and engulf them, flatten the nanowires or simply reside on top of them. Given the complexity of interactions, we have categorised our observations and created an overview map. The results demonstrate that detailed nanoscale resolution images are required to begin understanding the wide variety of individual cells’ interactions with a structured substrate. The map will provide a framework for light microscopy studies of such interactions indicating what modes of interactions must be considered.


Nanoscale | 2016

Detection of nerve gases using surface-enhanced Raman scattering substrates with high droplet adhesion

Aron Hakonen; Tomas Rindzevicius; Michael Stenbæk Schmidt; Per Ola Andersson; Lars Juhlin; Mikael Svedendahl; Anja Boisen; Mikael Käll

Threats from chemical warfare agents, commonly known as nerve gases, constitute a serious security issue of increasing global concern because of surging terrorist activity worldwide. However, nerve gases are difficult to detect using current analytical tools and outside dedicated laboratories. Here we demonstrate that surface-enhanced Raman scattering (SERS) can be used for sensitive detection of femtomol quantities of two nerve gases, VX and Tabun, using a handheld Raman device and SERS substrates consisting of flexible gold-covered Si nanopillars. The substrate surface exhibits high droplet adhesion and nanopillar clustering due to elasto-capillary forces, resulting in enrichment of target molecules in plasmonic hot-spots with high Raman enhancement. The results may pave the way for strategic life-saving SERS detection of chemical warfare agents in the field.


Nanotechnology | 2011

Fast and direct measurements of the electrical properties of graphene using micro four-point probes

Mikkel Buster Klarskov; H F Dam; Dirch Hjorth Petersen; Torben Mikael Hansen; A Löwenborg; Tim Booth; Michael Stenbæk Schmidt; Rong Lin; Peter Folmer Nielsen; Peter Bøggild

We present measurements of the electronic properties of graphene using a repositionable micro four-point probe system, which we show here to have unique advantages over measurements made on lithographically defined devices; namely speed, simplicity and lack of a need to pattern graphene. Measurements are performed in ambient, vacuum and controlled environmental conditions using an environmental scanning electron microscope (SEM). The results are comparable to previous results for microcleaved graphene on silicon dioxide (SiO(2)). We observe a pronounced hysteresis of the charge neutrality point, dependent on the sweep rate of the gate voltage; and environmental measurements provide insight into the sensor application prospects of graphene. The method offers a fast, local and non-destructive technique for electronic measurements on graphene, which can be positioned freely on a graphene flake.


COPD: Journal of Chronic Obstructive Pulmonary Disease | 2014

Contribution of CT Quantified Emphysema, Air Trapping and Airway Wall Thickness on Pulmonary Function in Male Smokers With and Without COPD

Firdaus A. A. Mohamed Hoesein; Pim A. de Jong; Jan-Willem J. Lammers; Willem P. Th. M. Mali; Onno M. Mets; Michael Stenbæk Schmidt; Harry J. de Koning; Carlijn M. van der Aalst; Matthijs Oudkerk; Rozemarijn Vliegenthart; Bram van Ginneken; Eva M. van Rikxoort; Pieter Zanen

Abstract Emphysema, airway wall thickening and air trapping are associated with chronic obstructive pulmonary disease (COPD). All three can be quantified by computed tomography (CT) of the chest. The goal of the current study is to determine the relative contribution of CT derived parameters on spirometry, lung volume and lung diffusion testing. Emphysema, airway wall thickening and air trapping were quantified automatically on CT in 1,138 male smokers with and without COPD. Emphysema was quantified by the percentage of voxels below –950 Hounsfield Units (HU), airway wall thickness by the square root of wall area for a theoretical airway with 10 mm lumen perimeter (Pi10) and air trapping by the ratio of mean lung density at expiration and inspiration (E/I-ratio). Spirometry, residual volume to total lung capacity (RV/TLC) and diffusion capacity (Kco) were obtained. Standardized regression coefficients (β) were used to analyze the relative contribution of CT changes to pulmonary function measures. The independent contribution of the three CT measures differed per lung function parameter. For the FEV1 airway wall thickness was the most contributing structural lung change (β = –0.46), while for the FEV1/FVC this was emphysema (β = –0.55). For the residual volume (RV) air trapping was most contributing (β = –0.35). Lung diffusion capacity was most influenced by emphysema (β = –0.42). In a cohort of smokers with and without COPD the effect of different CT changes varies per lung function measure and therefore emphysema, airway wall thickness and air trapping need to be taken in account.


Optics Express | 2015

Plasmon resonances of Ag capped Si nanopillars fabricated using mask-less lithography

Kaiyu Wu; Tomas Rindzevicius; Michael Stenbæk Schmidt; Klaus Bo Mogensen; Sanshui Xiao; Anja Boisen

Localized surface plasmon resonances (LSPR) and plasmon couplings in Ag capped Si Nanopillar (Ag NP) structures are studied using 3D FEM simulations and dark-field scattering microscopy. Simulations show that a standalone Ag NP supports two LSPR modes, i.e. the particle mode and the cavity mode. The LSPR peak position of the particle mode can be tuned by changing the size of the Ag cap, and can be hybridized by leaning of pillars. The resonance position of the cavity resonance mode can be tuned primarily via the diameter of the Si pillar, and cannot be tuned via leaning of Ag NPs. The presence of a substrate dramatically changes the intensity of these two LSPR modes by introducing constructive and destructive interference patterns with incident and reflected fields. Experimental scattering spectra can be interpreted using theoretical simulations. The Ag NP substrate displays a broad plasmonic resonance band due to the contribution from both the hybridized particle LSPR and the cavity LSPR modes.


Journal of Vacuum Science & Technology B | 2006

Comparison of high resolution negative electron beam resists

Brian Bilenberg; M. Schøler; P. Shi; Michael Stenbæk Schmidt; Peter Bøggild; M. Fink; C. Schuster; F. Reuther; C. Gruetzner; Anders Kristensen

Four high resolution negative electron beam resists are compared: TEBN-1 from Tokuyama Corp. Japan, ma-N 2401XP and mr-L 6000.1XP from microresist technology GmbH Germany, and SU-8 2000 series from MicroChem Corp., USA. Narrow linewidth high density patterns are defined by 100kV electron beam lithography, and the pattern is transferred into silicon by a highly anisotropic SF6∕O2∕CHF3 based reactive ion etch process with a selectivity between silicon and the investigated resists of approximately 2. 20nm half-pitch lines and 10nm lines with a pitch down to 60nm are written and transferred into silicon.

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Dive into the Michael Stenbæk Schmidt's collaboration.

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Anja Boisen

Technical University of Denmark

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Kaiyu Wu

University of Copenhagen

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Tommy Sonne Alstrøm

Technical University of Denmark

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Ole Hansen

Technical University of Denmark

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Anil Haraksingh Thilsted

Technical University of Denmark

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Rasmus Schmidt Davidsen

Technical University of Denmark

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Anja Boisen

Technical University of Denmark

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Jörg Hübner

Technical University of Denmark

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Mogens Havsteen Jakobsen

Technical University of Denmark

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