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Dive into the research topics where Han Gardeniers is active.

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Featured researches published by Han Gardeniers.


IEEE\/ASME Journal of Microelectromechanical Systems | 2003

Silicon micromachined hollow microneedles for transdermal liquid transport

Han Gardeniers; Regina Lüttge; Erwin Berenschot; de M.J. Boer; Shuki Y. Yeshurun; Meir Hefetz; van 't Ronny Oever; van den A. Berg

This paper presents a novel process for the fabrication of out-of-plane hollow microneedles in silicon. The fabrication method consists of a sequence of deep-reactive ion etching (DRIE), anisotropic wet etching and conformal thin film deposition, and allows needle shapes with different, lithography-defined tip curvature. In this study, the length of the needles varied between 150 and 350 micrometers. The widest dimension of the needle at its base was 250 /spl mu/m. Preliminary application tests of the needle arrays show that they are robust and permit skin penetration without breakage. Transdermal water loss measurements before and after microneedle skin penetration are reported. Drug delivery is increased approximately by a factor of 750 in microneedle patch applications with respect to diffusion alone. The feasibility of using the microneedle array as a blood sampler on a capillary electrophoresis chip is demonstrated.


Journal of Micromechanics and Microengineering | 1996

A survey on the reactive ion etching of silicon in microtechnology

Henri V. Jansen; Han Gardeniers; Meint J. de Boer; M.C. Elwenspoek; Jan H.J Fluitman

This article is a brief review of dry etching as applied to pattern transfer, primarily in silicon technology. It focuses on concepts and topics for etching materials of interest in micromechanics. The basis of plasma-assisted etching, the main dry etching technique, is explained and plasma system configurations are described such as reactive ion etching (RIE). An important feature of RIE is its ability to achieve etch directionality. The mechanism behind this directionality and various plasma chemistries to fulfil this task will be explained. Multi-step plasma chemistries are found to be useful to etch, release and passivate micromechanical structures in one run successfully. Plasma etching is extremely sensitive to many variables, making etch results inconsistent and irreproducible. Therefore, important plasma parameters, mask materials and their influences will be treated. Moreover, RIE has its own specific problems, and solutions will be formulated. The result of an RIE process depends in a non-linear way on a great number of parameters. Therefore, a careful data acquisition is necessary. Also, plasma monitoring is needed for the determination of the etch end point for a given process. This review is ended with some promising current trends in plasma etching.


Mechatronics | 2000

The electrolysis of water: an actuation principle for MEMS with a big opportunity

Cristina Neagu; Henri V. Jansen; Han Gardeniers; M.C. Elwenspoek

In this paper the theory of water electrolysis in a closed electrochemical cell, that contains two electrodes, an electrolyte and a pressure sensor is described. From the leakage and electrochemical experiments done with this macrocell it is possible to obtain information about the applicability of the electrochemical principle in a closed cavity, the choice of the electrodes and electrolyte, and different types of leakage. To control the pressure of the electrochemical actuator automatically, an electronic feedback system was connected to the cell. A value of the pressure is set and the regulator will actuate the electrochemical cell in such a way to get the desired pressure.


Journal of the American Chemical Society | 2009

Nanostructure Based on Polymer Brushes for Efficient Heterogeneous Catalysis in Microreactors

Francesca Costantini; Wojciech P. Bula; Riccardo Salvio; Jurriaan Huskens; Han Gardeniers; David N. Reinhoudt; Willem Verboom

PGMA polymer brushes are successfully grown on the inner wall of a microreactor to give a nanostructure. The oxirane groups of the brushes are used for the anchoring of a catalyst. The utility of the combination of catalyst-functionalized brushes and a microreactor is clearly demonstrated for the TBD-catalyzed Knoevenagel condensation reaction of benzaldehyde and malononitrile.


Ultrasonics Sonochemistry | 2012

Sonoluminescence and sonochemiluminescence from a microreactor

David Fernandez Rivas; Muthupandian Ashokkumar; Thomas Leong; Kyuichi Yasui; Toru Tuziuti; Sandra E. Kentish; Detlef Lohse; Han Gardeniers

Micromachined pits on a substrate can be used to nucleate and stabilize microbubbles in a liquid exposed to an ultrasonic field. Under suitable conditions, the collapse of these bubbles can result in light emission (sonoluminescence, SL). Hydroxyl radicals (OH()) generated during bubble collapse can react with luminol to produce light (sonochemiluminescence, SCL). SL and SCL intensities were recorded for several regimes related to the pressure amplitude (low and high acoustic power levels) at a given ultrasonic frequency (200kHz) for pure water, and aqueous luminol and propanol solutions. Various arrangements of pits were studied, with the number of pits ranging from no pits (comparable to a classic ultrasound reactor), to three-pits. Where there was more than one pit present, in the high pressure regime the ejected microbubbles combined into linear (two-pits) or triangular (three-pits) bubble clouds (streamers). In all situations where a pit was present on the substrate, the SL was intensified and increased with the number of pits at both low and high power levels. For imaging SL emitting regions, Argon (Ar) saturated water was used under similar conditions. SL emission from aqueous propanol solution (50mM) provided evidence of transient bubble cavitation. Solutions containing 0.1mM luminol were also used to demonstrate the radical production by attaining the SCL emission regions.


Nanomedicine: Nanotechnology, Biology and Medicine | 2012

In vitro and in vivo evaluation of the inflammatory response to nanoscale grooved substrates

Edwin Lamers; X. Frank Walboomers; Maciej Domanski; L. Prodanov; Jacoline Melis; Regina Lüttge; Louis Winnubst; James M. Anderson; Han Gardeniers; John A. Jansen

The immune response to an implanted biomaterial is orchestrated by macrophages. In this study various nanogrooved patterns were created by using laser interference lithography and reactive ion etching. The created nanogrooves mimic the natural extracellular matrix environment. Macrophage cell culture demonstrated that interleukin 1β and TNF-α cytokine production were upregulated on nanogrooved substrates. In vivo subcutaneous implantation in a validated mouse cage model for 14 days demonstrated that nanogrooves enhanced and guided cell adhesion, and few multinucleated cells were formed. In agreement with the in vitro results, cytokine production was found to be nanogroove dependent, as interleukin 1β, TNF-α, TGF-β and osteopontin became upregulated. The results indicate that biomaterial surface texturing, especially at the nanometric scale, can be used to control macrophage activation to induce a wound healing response, rather than a profound inflammatory response. From the Clinical Editor: The authors investigate various nano-grooved patterns that mimic the natural extracellular matrix environment and demonstrate (both in macrophage cultures and in vivo) that interleukin 1β and TNF-α cytokine production is dependent upon surface texturing at the nanometric scale. They propose that modified surfaces may trigger macrophage activation to promote a wound healing response.


Biomicrofluidics | 2012

Localized removal of layers of metal, polymer, or biomaterial by ultrasound cavitation bubbles

David Fernandez Rivas; B. Verhaagen; James Richard Thorley Seddon; Aaldert Zijlstra; Lei-Meng Jiang; Luc van der Sluis; Michel Versluis; Detlef Lohse; Han Gardeniers

We present an ultrasonic device with the ability to locally remove deposited layers from a glass slide in a controlled and rapid manner. The cleaning takes place as the result of cavitating bubbles near the deposited layers and not due to acoustic streaming. The bubbles are ejected from air-filled cavities micromachined in a silicon surface, which, when vibrated ultrasonically at a frequency of 200 kHz, generate a stream of bubbles that travel to the layer deposited on an opposing glass slide. Depending on the pressure amplitude, the bubble clouds ejected from the micropits attain different shapes as a result of complex bubble interaction forces, leading to distinct shapes of the cleaned areas. We have determined the removal rates for several inorganic and organic materials and obtained an improved efficiency in cleaning when compared to conventional cleaning equipment. We also provide values of the force the bubbles are able to exert on an atomic force microscope tip.


Journal of Chromatography A | 2009

Effect of the presence of an ordered micro-pillar array on the formation of silica monoliths

Frederik Detobel; Hamed Eghbali; Selm De Bruyne; H. Terryn; Han Gardeniers; Gert Desmet

We report on the synthesis of siloxane-based monoliths in the presence of a two-dimensional, perfectly ordered array of micro-pillars. Both methyltrimethoxysilane- and tetramethoxysilane-based monoliths were considered. The obtained structures were analyzed using scanning-electron microscopy and can be explained from the general theory of surface-directed phase separation in confined spaces. The formed structures are to a large extent nearly exclusively determined by the ratio between the bulk domain size of the monolith on the one hand and the distance between the micro-pillars on the other hand. When this ratio is small, the presence of the pillars has nearly no effect on the morphology of the produced monoliths. However, when the ratio approaches unity and ascends above it, some new types of monolith morphologies are induced, two of which appear to have interesting properties for use as novel chromatographic supports. One of these structures (obtained when the domain size/inter-pillar distance ratio is around unity) is a 3D network of linear interconnections between the pillars, organized such that all skeleton branches are oriented perpendicular to the micro-pillar surface. A second interesting structure is obtained at even higher values of the domain size/inter-pillar distance ratio. In this case, each individual micro-pillar is uniformly coated with a mesoporous shell.


Analytical and Bioanalytical Chemistry | 2009

Chemistry in nanochannel confinement

Han Gardeniers

This review addresses the questions of whether it makes sense to use lithographically defined nanochannels for chemistry in liquids, and what it is possible to learn from experiments on that topic. The behavior of liquids in different classes of pores (categorized according to their size) is reviewed, with a focus on chemical reactions and protein dynamics. A number of interesting phenomena are discussed for nanochannels with feature sizes that are manufacturable with modern photolithography-based fabrication technology. The use of spectroscopic methods to investigate chemistry in nanochannels, where both spectroscopic method and nanochannels are integrated into a single device, will be evaluated.


Advanced Materials | 2015

Fabrication and doping methods for silicon nano- and micropillar arrays for solar cell applications: a review

Rick Elbersen; Wouter Vijselaar; Roald M. Tiggelaar; Han Gardeniers; Jurriaan Huskens

Silicon is one of the main components of commercial solar cells and is used in many other solar-light-harvesting devices. The overall efficiency of these devices can be increased by the use of structured surfaces that contain nanometer- to micrometer-sized pillars with radial p/n junctions. High densities of such structures greatly enhance the light-absorbing properties of the device, whereas the 3D p/n junction geometry shortens the diffusion length of minority carriers and diminishes recombination. Due to the vast silicon nano- and microfabrication toolbox that exists nowadays, many versatile methods for the preparation of such highly structured samples are available. Furthermore, the formation of p/n junctions on structured surfaces is possible by a variety of doping techniques, in large part transferred from microelectronic circuit technology. The right choice of doping method, to achieve good control of junction depth and doping level, can contribute to an improvement of the overall efficiency that can be obtained in devices for energy applications. A review of the state-of-the-art of the fabrication and doping of silicon micro and nanopillars is presented here, as well as of the analysis of the properties and geometry of thus-formed 3D-structured p/n junctions.

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Gert Desmet

VU University Amsterdam

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Roald M. Tiggelaar

MESA+ Institute for Nanotechnology

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Wim De Malsche

Vrije Universiteit Brussel

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Albert van den Berg

MESA+ Institute for Nanotechnology

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Erwin Berenschot

MESA+ Institute for Nanotechnology

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Jurriaan Huskens

MESA+ Institute for Nanotechnology

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Stefan Schlautmann

MESA+ Institute for Nanotechnology

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David Clicq

Vrije Universiteit Brussel

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