Publications by Vahid Fakhfouri

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Incorporation of nanoparticles into photostructurable polymer materials enables the engineering of novel, highly integrated micro/nanosystems (MEMS/NEMS) with enhanced intrinsic functional properties. For instance, nanoparticles with (semi)conducting, optical or magnetic properties can be incorporated into polymers in order to convey their inherent functionalities to the final material, which can then be exploited for sensor and actuator applications. The current challenge is two-fold: (a) the incorporation

In recent years a wide range of materials including metals, semiconductors and metal oxides have been synthesized with nanometer dimensions. In particular II–VI semiconductor nanocrystals (NCs) are receiving considerable attention for fundamental studies as zerodimensional quantum confined material and for their potential application in optoelectronics and photonics. The colour tunability of the emission of semiconductor NCs as a function of size is one of their most attractive properties. A current bottle-

Inkjet printing of functional materials, photolithography and micromolding are 3 different techniques largely used in the field of micro-electromechanical systems (MEMS) with increasing interest for the fabrication of new devices and the development of new ...

Increasing interest in specific applications in the field of micro- and nano-electromechanical systems (MEMS and NEMS) has raised the request for new functional polymeric materials. Epoxy based photoresists are being broadly used for the fabrication of micromechanical devices and for the definition of patterns with high aspect ratio in the micrometer scale. SU-8, the well known thick photo resist with superior lithographic properties over a wide range of thicknesses, have made a tremendous impact on the dev

The organic polymers incorporating inorganic nanoparticles can result in material possessing with unique size-dependent properties, such as mechanical, optical, electrical, thermal and magnetic, that can be istinctively conveyed into the composite by the suitable nanoparticles. When nano-objects such as luminescent nanocrystals (NCs) particles are embedded into photostructurable polymer materials, they provide a new, highly processable material, which enables the engineering of novel, highly integrated micr

An epoxy-based negative-tone photoresist, which is known as a suitable material for high-aspect-ratio surface micromachining, is functionalized with red-light-emitting CdSe@ZnS nanocrystals (NCs). The proper selection of a common solvent for the NCs and th ...

In this project, we intend to use inkjet-based delivery of functional liquid droplets on pre-structured surfaces for the directed (self-)assembly of micro/nano-objects as experimental platform to build up and validate multi-level models of micro-droplet deposition, spanning from simple equations of motion to realistic, computationally intensive simulations. Furthermore, we aim to exploit these simulations to achieve the computer-aided design of functional surfaces that improve the precision of final positio

Inkjet printing is a very common and largely developed technology in desktop printers. A wide range of diverse technologies, with different principles of drop generation, fall into the inkjet printing category. Inkjet technology, particularly the drop-on-demand mode for drop generation, is widely applicable in micro/nano electromechanical systems (MEMS/NEMS) and is promising for further developments in this domain. We are investigating the potentials of inkjet printing for the fabrication of MEMS and NEMS a

Chemical inertness and corrosion resistance make ceramic materials appropriate for Micro Electro-Mechanical Systems (MEMS) when aiming for sensing applications at high temperature or in harsh environment. Besides the usual fabrication techniques, such as powder-injection moulding, applied for macro structures, new methods were recently developed based on the use of liquid precursors for engineering of ceramic MEMS. Microinjection and photopolymerisation of e.g. Polyureasilazane (a precursors for SiC and Si-

Microlens arrays fabricated by a direct ink-jet printing of UV-curable hybrid polymer are reported. A periodic pattern of polymer drops was ink-jet printed on the surface-treated glass substrate and cured in the UV-light. Using this simple technique, we de ...

We develop ceramic structures using ceramic-precursor polymers. The possibility to modify easily the physical properties of the final ceramic structures just by doping the precursor with nanoparticles, makes them interesting for new MEMS and NEMS developments. Here, we describe a technique to microfabricate conductor cantilever structures in ceramic. The fabrication involves microfabrication techniques such as micromoulding with high aspect-ratio SU-8 patterning and thick-film structuring of ceramicprecurso

This paper describes a novel method to fabricate polymer MEMS based on the inkjet printing of SU-8, with a special emphasis on integrated micro-optical lens arrays. Inkjet control parameters are optimized in order to enable a stable and reproducible ejecti ...

We describe a novel surface micromachining process for the fabrication of ceramic-type MEMS devices, such as free-standing cantilevers, that is based on the use of high-aspect ratio micromolds of SU8 and aluminum as sacrificial layer. 250μm-high and 100-1000μm-wide molds were used to confine a liquid precursor of SiC/Si3N4 based ceramics on the sacrificial layer that enables the detachment of the green body before the pyrolysis step at 1000°C. The final ceramic cantilever has dimensions ranging from 100-500

Inkjet printing (IJP) is a contactless method of printing and has found wide applications in the packaging and printing industries. In order to get patterned micro-structures with specific morphology via inkjet technology, predefined molds from SU8 with different shapes, and with different parameters, were realized to serve as molds for polymeric droplets.

There is growing interest for new polymer materials and their applications in Micro Electro/Mechanical Systems (MEMS). In this work, we develop recyclable micro-moulds that can be used for microstructuring of new polymer materials, such as precursors and modified or doped polymers. The moulds are made by photopolymerisation of SU8. A sacrificial layer (thickness: 500nm), of aluminum is then sputtered on the moulds. This layer is later removed to release the final structures. The moulds are filled with a liq

Inkjet technology is a compelling method for the flexible and cost-effective printing of functional inks. We show that nanocomposite solutions based on polystyrene and differently sized core/shell-type nanocrystals (NCs) formed by a CdSe core coated with a ...

Inkjet printing technology is an emerging deposition method for the flexible and cost-effective dispensing of functional materials. In this work, luminescent single- and multi-colour pixel arrays of chloroform nanocomposite inks based on polystyrene (PS) f ...

In this contribution, we describe a novel approach to the problem of setting micrometric droplets in motion. After a short review of the state-of-the-art methods to enable droplet motion, we investigate the scalability of the most promising techniques by using numerical models and systematic experiments. Finally, we propose and evaluate a novel approach based on substrates with radial 3D pattern.

Ink-jet printing technique allows locally and precisely dispensing materials for the manufacturing of micro-scale structures. We present the fabrication of piano-convex microlenses using a hybrid organic-inorganic photo-curable polymer diluted in gamma-but ...

Vahid Fakhfouri

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High-aspect ratio three-dimensional photoresin-based microstructures doped with luminescent nanocrystals

Nanocomposites based on luminescent colloidal nanocrystals in polymers: new opportunities for micro and nano fabrication

Inkjet printing and high aspect ratio structuring for polymer-based micro and nano systems

Improved and new properties of resist materials by doping with nanoparticles and nanocrystals

Luminescent nanocrystal modified photoresin for fabrication of high-aspect ratio three-dimensional microstructures

An Epoxy Photoresist Modified by Luminescent Nanocrystals for the Fabrication of 3D High-Aspect-Ratio Microstructures

Inkjet-Based Deposition of Micro/Nano-Objects on Functional Surfaces - Controlling and Exploiting Self-Assembly across Length-Scales

Ink-Jetting of Polymers and Biomaterials

Surface micromachining of Ceramic-MEMS based on SU-8 micromoulding of Polyureasilazane

Hybrid polymer microlens arrays with high numerical apertures fabricated using simple ink-jet printing technique

MICRO-MOULDING OF CERAMIC STRUCTURES USING CERAMIC-PRECURSOR POLYMERS

Inkjet printing of SU-8 for polymer-based MEMS a case study for microlenses

Surface Micromachining of Polyureasilazane Based Ceramic-MEMS using SU-8 Micromolds

Surface Micromachining of Polyureasilazane Based Ceramic-MEMS using SU-8 Micromolds

MICROFABRICATED MOLDS FOR INKJET APPLICATIONS

MICROFABRICATED RECYCLABLE MOULDS FOR FULL-WAFER STRUCTURING OF CERAMIC PRECURSOR POLYMERS

Inkjet-Printed Multicolor Arrays of Highly Luminescent Nanocrystal-Based Nanocomposites

Drop-on-demand inkjet printing of highly luminescent CdS and CdSe@ZnS nanocrystal based nanocomposites

Micrometric Droplets Motion

Direct Fabrication of Polymer Micro lens Arrays having Tunable Optical Properties using Drop-On-Demand Ink-Jet Printing Technology