Low-cost embedded spirometer based on micro machined polycrystalline thin film

There is a great need for a low cost and low power consumption portable spirometer for the home care of respiratory diseases. A mobile monitoring system utilizing Bluetooth and mobile messaging services (SMS) with low-cost hardware equipment is proposed. A proof of concept prototype has been developed and implemented to enable transmission of a flow or volume of gas during inspiratory and expiratory process signal of a patient, which can be expanded to include other vital signs. Communication between a mobile smart-phone and the spirometer is implemented using the popular personal area network standard specification Bluetooth. We used SMS for transmission, the mobile phone plots the received signal and displays the flow measurement application software running on the client mobile phone itself, where the plot can be captured and saved as an image before transmission. The acquired signal is transmitted via the Bluetooth to the processing and diagnostic unit with wireless protocol between sensors and the electronics board. The flow measurement is done with a silicon hot wire anemometer manufactured with MEMS technology. The design, manufacturing, calibration, and basic characterization of MEMS hot-wire anemometer and digital spiromerter is presented.     

Analytic modeling, optimization, and realization of cooling devicesin silicon technology

A novel cooling device fully built in silicon technology is presented. The new concept developed in this work consists of micromachining the bottom side of the circuit wafer in order to embed heat sinking microchannels directly into the silicon material. These microchannels are then sealed, by a direct wafer bonding procedure, with another silicon wafer where microchannels and inlet-outlet nozzles are micromachined too. A cooling fluid (water) is then forced through the array of channel to convey heat outside the chip. Such a configuration presents advantages to provide a significant reduction of the cooler overall dimensions, to reduce the number of the involved materials and to be compatible with integrated circuit fabrication procedures, In this study analytical tools were used in order to get a global evaluation of all the thermal resistances characteristic of such devices. Using these adequate analytic models with appropriate approximations, a global optimization procedure was then applied and led to the definition of he optimum dimensions of the silicon micro heat sink. The realization procedure was then carried out in a clean room environment. First experimental characterization results obtained from the earlier prototypes demonstrated that the thermal properties of this silicon-based cooling device are satisfactory and can be reasonably compared to those of commercially available copper micro heat sinking components     

Realization and simulation of wall shear stress integrated sensors

In this paper we present the impact of hot wire geometry and fluid characteristics on the efficiency of a hot wire to be used as a wall shear stress sensor. Finite differences and finite elements modelling based simulators were used in order to evaluate the thermal performances of hot wire wall shear stress sensor. Several structures were explored including simple conductor or suspended above a cavity (free and sealed with an oxide membrane). It is found out that wire length, wire section and the dimensions of the micro-cavity lying below the hot wire are of fundamental importance on the thermal exchanges occurring between the hot wire and the fluid.     

Stamp replication for thermal and UV nanoimprint lithography using a UV-sensitive silsesquioxane resist

The mask fabrication is a critical issue for the development of nanoimprint lithography (NIL) as an effective low-cost mass production technique. In this paper, we present results on the synthesis and the use of low-viscosity hybrid organic/inorganic resists based on polyhedral silsesquioxane cages functionalized with photo-polymerizable aliphatic epoxy groups. These materials are very attractive because they present a high thermal and mechanical resistance (as well as a reduced dielectric constant) and they can be processed by ultraviolet (UV)-assisted NIL. For these reasons, they are good candidates for the fabrication of 2nd generation stamps for both thermal and UV-NIL.     

Stripping Hall effect, sheet and spreading resistance techniques for electrical evaluation of implanted silicon layers

The objective of this chapter is to address the electrical characterization of silicon implanted layer. The determination of the electrical activity profiles, in terms of free carriers concentration and mobility, is described using spreading resistance and stripping Hall effect techniques. Several recent results are presented in order to show the importance of such experimental analysis     

Degradation and surfactant-aided regeneration of fluorinated anti-sticking mold treatments in UV nanoimprint lithography

In nanoimprint lithography, the most common approach to prevent resist to adhere to the mold is to graft a fluorinated anti-sticking layer on the mold’s surface. But it is known that these layers suffer from degradation after a certain number of imprints. In this work, we study the influence of the presence, type and quantity of fluorinated surfactant additives in the resist formulation on the degradation of the mold’s treatment. It is found that the presence of a fluorinated surfactant drastically increases the possible maximal number of imprints before retreatment. Also, we observed that fluorinated surfactants with a silane end-group are able to be adsorbed at the surface of the mold after repeated imprints to progressively replace the initial mold’s treatment. Nevertheless, a balance has still to be found between quantity, reactivity and type of surfactant to maintain a smooth and extremely thin fluorinated layer at the surface of the mold.     

Fabrication flaws and reliability in MEMS thin film polycrystalline flow sensor

A micro hot wire anemometer sensor has been constructed. The process consists in depositing a thin doped polycrystalline silicon layer on silicon substrate, using a micro-machined technique. This paper discusses the reliability and the fabrication flaws of this sensor. The different steps of fabrication are oxidation, deposit, photolithography, chemical attack, ionic implantation and annealing. An additional step, allowing the release of the suspended structures, is added. With each technological process step, a certain number of problems can be met. Each of these problems can potentially give rise to a defect of the final structure. Various tests are carried out on the final structure to make a first approach of the micro flow sensor flaws.     

A miniature silicon hot wire sensor for automatic wind speed measurements

In order to make air flow measurements easier and more accurate, a very small sensor has been constructed. The fabrication of such a sensor mainly consists in depositing a thin doped polycrystalline silicon layer on a 4″ silicon wafer by using a silicon—micromachined technique. At the end of the integration process, the wafer is sliced into 46 wind sensors. Each of them comprises a polycrystalline silicon layer which is 0.5 μm thick, with width running from 2 to 5 μm and length, from 45 to 58 μm. Supplied with a dc electrical current, each layer acts as a hot wire on contact with the fluid under study. Wind speed is then measured by detecting the resistance variations caused by the thermal transfer from the heated layer to the ambient atmosphere. A microcontroller-based data acquisition system has especially been designed so as to collect the wind speed measurements arising from this kind of hot wire transducer. The integrated silicon sensors have been experimented within a wind tunnel and calibrated for air speed ranging from 0 to 35 m/s. Initially intended for wall shear stress monitoring, these sensors can usefully be employed as anemometers for wind energy applications.     

Caractérisation électrique des composants MOS

We present a set of practical manipulations for MOS component characterisation, which is included in a cycle of practical teaching of microelectronics technology. Hardware include a computer controling impedance analyser and a picoamperemeter. The software we present enable the complete characterization of a technological chip which has been specially conceived for educational purpose. The parameter extraction procedure includes : exhaustive analysis of C-V curves (high frequency and quasi static), doping profile obtained from C-V analysis, Zerbst analysis, and analysis of I_d(V_g,V_d) characteristics ofMOS transistors, with extraction of the following parameters : threshold voltage, mobility and mobility reduction factor, sub-threshold swing, series resistance, electrical length and width.     

Multi criteria analysis for locating sustainable suburban centers: A case study from Ramallah Governorate, Palestine

Currently, over 65% of Palestinians live in urban areas, exceeding the international urbanization rate of 50%. The Ramallah Governorate is the most rapidly growing governorate within the Palestinian territory. This accelerating urban growth is accompanied by significant pressure on services, employment opportunities, and accommodations. This study aimed at finding sustainable areas for absorbing urban growth within Ramallah in order to alleviate the pressure on the city center as well as find accommodations for young families looking for better living conditions. This research was conducted in two major phases. Site selection was the first phase, using Geographic Information System (GIS to identify 13 sites according to the determined criteria. In Phase Two, Multi Criteria Analysis (MCA) was applied to evaluate these sites considering a set of indicators, which were evaluated and assessed by a wide range of stakeholders. Expert and public participation were included in this study. As a result of consideration of over 20 variables, a site was selected to be the most sustainable place for developing a suburban center within the study area.