Salle blanche | EPFL Graph Search

vignette|Combinaison avec masque typique des salles blanches. Une salle blanche (parfois dénommée salle propre selon l'usage et certaines spécificités) est une pièce ou une série de pièces où la concentration particulaire est maîtrisée afin de minimiser l'introduction, la génération, la rétention de particules à l'intérieur, généralement dans un but spécifique industriel ou de recherche scientifique. Les paramètres tels que la température, l'humidité et la pression relative sont également maintenus à un niveau précis. Ce type de salle est régi par une norme à deux niveaux : la norme ISO 14664 donne les exigences techniques générales, la norme ISO 14644-1 précise le volume de prélèvement d'air en échantillon de contrôle en fonction de la classe attendue afin de maintenir la conformité de l'ISO 14644. Histoire Le principe de la salle blanche a été imaginé par le physicien Willis Whitfield en 1960, alors employé par les Laboratoires Sandia, qui remarqua que ses expérien

Exploration of micro-acoustic spectrometry techniques

Florian Fernand Hartmann

This master’s thesis aimed at exploring the field of micro-acoustic spectrometry using surface acoustic waves. The objectives of this project were to design and fabricate a platform for the detection and characterization of bioentities. Design of a delay line based on the experience and knowledge of the ANEMS group and on investigation of existing solutions was performed. Different configurations and types of transducers were simulated to come up with some meaningful designs for fabrication. The devices were fabricated in the clean rooms at EPFL with a specific process flow used for the suspended structures. Extensive simulation of bidirectional and unidirectional transducers were carried out in order to understand their behavior and to be able to use them as the elements of the sensing platform. Setbacks prevented the completion of the fabrication and no real measurements could be done before the end of this project, but the simulations gave nice perspectives for the targeted application. The potential of surface acoustic waves to detect modifications in the elasticity or the density of a material could be witnessed in the last simulations.

2022

Microchannel fabrication

Claudia Castillo Moreno, Tom Larsen

In this project, we have studied a new microchannel fabrication technique based on the idea of the transference of a thin layer of Si3N4 on top of grooves to form channels. In order to do so, we have created two different wafers. The first of them was a silicon wafer with grooves. We have covered this wafer with Si3N4 and cut it into chips. The other one was a Si wafer covered with Si3N4 on one of its sides. The wafer is cut into chips and thinned down to a thickness of about 50 um. Both processes have been carried out at a clean room. The next steps have taken place in a laboratory. In this environment, we have etched the Si from the Si3N4 chips until we had a thin layer of Si3N4 and transfer this layer on the top of the chips with grooves. After analyzing the complete microchannel chips with the microscope, we have concluded that this process can be a good alternative to existing fabrication techniques.

2017

PyroMEMS: Improved Fabrication Methods and Ignition Reliability

David de Koninck

Generating large force/displacement actuators at the millimeter and sub-millimeter scales remains an important challenge for microsystems engineers. One promising solution is to integrate high-energy density solid propellant fuels in microsystems (pyroMEMS) to generate high-pressure, high-temperature combustion gases. However, integrating combustible materials within microsystems is non-trivial: solid propellant fuels are generally integrated manually into the device during back-end processing leading to large variability in the device performance. The goal of this thesis was to improve pyroMEMS reliability and performance. Reliability is particularly important for single-use devices –such as pyroMEMS– that cannot be tested before use. This was accomplished by simplifying their fabrication process and developing experimentally-validated models to improve device performance. First, a solid propellant fuel –and associated deposition technique– was specifically formulated for use in pyroMEMS devices. The fuel used was a mixture of potassium 4,6-dinitrobenzofuroxan (K-DNBF) and binder. The propellant combustion was modeled using a chemical equilibrium code and validated experimentally by measuring the in situ pressure and temperature inside a pyroMEMS test device. We recorded combustion temperatures of 1300±160 °C and overpressures of up to 60±5 bar. These results were in good agreement with the values obtained from simulations. This represents the first such measurements ever carried out in pyroMEMS devices. Two complementary pyroMEMS igniters were developed in this thesis: a drop-coated bottom-side igniter and a top-side shadow-mask evaporated igniter. The bottom-side igniter concept was based on the peripheral heating and ignition of fuel droplets to obtain smooth, steady combustion without fuel peeling or ejection. The overall fabrication process was highly simplified and extremely robust –over 350 igniters were successfully fabricated and tested. An investigation of igniter performance based on substrate material, igniter layout, fuel binder content and input power was performed. Semi-analytical models were developed and successfully predicted the ignition behavior of the igniters. The top-side pyroMEMS igniter was fabricated by direct deposition of a metal igniter on the fuel surface via offset shadow mask evaporation. In this way, reliable ignition was ensured by the intimate thermal contact between the fuel and igniter. The ignition concept was successfully demonstrated on fuel drops and over top full fuel chambers without fuel degradation or ignition. Lastly, pyroMEMS balloon actuators for use in automated drug delivery systems and microfluidic actuators were designed, fabricated and tested. A foil-level fabrication technique using low-cost polymer materials and additive fabrication techniques was developed. The fabrication was compatible with cleanroom-free processing, thus facilitating solid propellant fuel integration. Balloon actuators were successfully inflated yielding membranes displacements of between 5 and 7.5 mm (for an initial membrane diameter of 5 mm). A semi-analytical model was developed that successfully predicted the balloon displacement. This work represents an important step in developing simple, large-scale fabrication techniques that minimize manual back-end processing in order to improve device reliability.

EPFL2012

PyroMEMS: Improved Fabrication Methods and Ignition Reliability

David de Koninck

EPFL2012