New Sacrificial Layer-Based Screen-Printing Process for Free-Standing Thick-Films Applied to MEMS

2007 ◽  
Vol 4 (3) ◽  
pp. 86-92 ◽  
Author(s):  
Claude Lucat ◽  
Patrick Ginet ◽  
Francis Ménil
Keyword(s):  
Aqueous Solution ◽  
Screen Printing ◽  
Sacrificial Layer ◽  
Strontium Carbonate ◽  
Inorganic Materials ◽  
Free Standing ◽  
New Process ◽  
Sacrificial Layers ◽  
Piezoelectric Transformers ◽  
Structural Layer

Thick-film sacrificial layers based on inorganic materials have been used for the fabrication of free-standing screen-printed films. A specific polymer ink based on a mixture of epoxy and strontium carbonate has been prepared for screen-printing of the sacrificial layer. After deposition and subsequent heat treatments of the structural and sacrificial layers, the latter is removed in an aqueous solution. The harmlessness and efficiency of the process have been demonstrated with regard to the structural layer(s). This new process, initially developed in our laboratory for the fabrication of a cantilever type beam, has been extended to the elaboration of an electrothermal actuator, constituted of two linked copper beams of different widths. The beams are partially suspended above the substrate to which they are anchored. Other developments include the fabrication of heating resistors and microchannels. Moreover, the process has been shown to facilitate the implementation of microassemblies such as piezoelectric transformers.

scholarly journals ADSORBATIVE SEPARATION OF DOXYCYCLINE FROM AQUEOUS SOLUTION WITH N,N-DIETHYL N-METHYL CHITOSAN, GUM AND POLYACRYLIC ACID BASED HYDROGELS

2021 ◽  
Vol 11 (07) ◽  
pp. 44-53
Author(s):  
Mirvari Hasanova Mirvari Hasanova
Keyword(s):  
Aqueous Solution ◽  
Ion Exchange ◽  
Zeta Potential ◽  
Polyacrylic Acid ◽  
Inorganic Materials ◽  
Biologically Active ◽  
Cross Linking ◽  
Separation And Purification ◽  
Inorganic Substances ◽  
The Cross

The separation and purification of antibiotics with sorption by ion-exchange materials, as well as their delivery in biological processes by immobilization, are now widely used in biotechnology. There are many scientific studies in the literature on the sorption of antibiotics by polymer-based sorbents and inorganic materials, as well as the study of thermodynamics and kinetics of the process. In the literature, the acquisition of biologically active systems from the sorption of antibiotics by ion-exchange fibers based on various polymers and inorganic substances was carried out. However, the synthesis of selective gels for the effective separation of doxycycline and its delivery in different pH mediums by sorption with biodegradable, biocompatible polysaccharide-containing composites is one of the topical issues. Gel was synthesized from the cross-linking of N,N-diethyl N-methyl derivative of a natural polyaminosaccharide of chitosan by glutaric aldehyde. Also, pH-sensitive hydrogels that can swollen in water were synthesized from the cross-linking of a graft copolymer of cherry source gummiarabic with N-vinylpyrrolidone, as well as synthetic polymer polyacrylic acid with N,N-methylene-bis-acrylamide. The structure of the gels were identified by FTIR and NMR spectroscopy, and the sorption of doxycycline antibiotic from an aqueous solution was investigated. According to the values of zeta potential, the protonation of functional groups in the main macromolecule in an acidic medium leads to a value of zeta potential of 40÷80 mV on the surface of chitosan-based gel and others. Although the chemical structure is different, the isoelectric point is set around pH=6÷8 for all three hydrogels. The dependences of the sorption process on the amount of gels, antibiotic concentration, temperature, and pH medium were studied. The experimental data were analyzed using two adsorption models, Langmuir and Freundlich, with the later system providing the best fit. Doxycycline is adsorbed on the surface of chitosan, gummiarabic and polyacrylic acid based hydrogel composite through by physical interactions. Also, the results of thermodynamic parameters ΔG40 kJ/mol show that the nature of the adsorption process is physical, and spontaneous, too. Keywords: Chitosan, Gummiarabic-arabinogalactane, polyacrylic acid, hydrogel, sorption isoterms, doxycycline, thermodynamica.

Study of self-actuated screen-printed PZT-cantilevers

2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000105-000110
Author(s):  
Riadh LAKHMI ◽  
Christophe CASTILLE ◽  
Hélène DEBEDA ◽  
Mario MAGLIONE ◽  
Claude LUCAT
Keyword(s):  
Screen Printing ◽  
Sintering Temperature ◽  
Sacrificial Layer ◽  
Longitudinal Vibration ◽  
Ferroelectric Ceramics ◽  
Mechanical Pressure ◽  
Bending Mode ◽  
Resonance Frequencies ◽  
Cantilever Structure ◽  
Screen Printed

Usually, resonating cantilevers come from silicon technology and are generally activated with pure bending mode. In this work, we suggest to combine high sensitive cantilever structure with full self-actuated piezoelectric thick-film for high electrical-mechanical coupling. This cantilever is realized through the screen-printing deposition associated with a sacrificial layer. The beam part of the cantilever is composed of a PZT layer between two gold electrodes. Optimum performances of ferroelectric ceramics strongly rely on their composition and microstructure which imply generally the use of mechanical pressure and very high sintering temperature. These conditions are not compatible with the screen-printing process. As already shown with ceramics, addition of eutectic composition Li2CO3-CuO-Bi2O3 or borosilicate glass-frit to PZT powder and application of isostatic pressure, the sintering temperature of cantilevers may be decreased. Screen-printed piezoelectric samples are thus fired at 850°C, 900°C and 950°C. SEM analyses show the densification of the microstructure while increasing the sintering temperature. Electrical and mechanical characterizations are then achieved after poling the self-actuated cantilevers of different dimensions. In addition to the bending mode observed with a vibrometer, we pointed out other resonances related to the piezoelectric properties of the PZT cantilevers. Indeed, the three first orders of “in-plane” 31-longitudinal vibration mode and the first order “out-of-plane” 33-thickness resonance mode are revealed. The resonance frequencies deduced from analytical modeling are linked to the cantilever dimensions and thus confirm the experimental results. The piezoelectric parameters of PZT cantilevers approach those of ceramics. Quality factors of 300 to 400 associated to the unusual 31-longitudinal mode make self-actuated screen-printed PZT cantilevers good candidates for detection in liquid and gaseous media.

scholarly journals Fabrication and Characterization of Roll-to-Roll Printed Air-Gap Touch Sensors

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 245 ◽  
Author(s):  
Sang Lee ◽  
Sangyoon Lee
Keyword(s):  
Printed Electronics ◽  
Sacrificial Layer ◽  
Flexible Substrate ◽  
Air Gap ◽  
Touch Sensor ◽  
Roll To Roll ◽  
Slot Die ◽  
Gap Sensors ◽  
Structural Layer

Although printed electronics technology has been recently employed in the production of various devices, its use for the fabrication of electronic devices with air-gap structures remains challenging. This paper presents a productive roll-to-roll printed electronics method for the fabrication of capacitive touch sensors with air-gap structures. Each layer of the sensor was fabricated by printing or coating. The bottom electrode, and the dielectric and sacrificial layers were roll-to-roll slot-die coated on a flexible substrate. The top electrode was formed by roll-to-roll gravure printing, while the structural layer was formed by spin-coating. In particular, the sacrificial layer was coated with polyvinyl alcohol (PVA) and removed in water to form an air-gap. The successful formation of the air-gap was verified by field emission scanning electron microscopy (FE-SEM). Electrical characteristics of the air-gap touch sensor samples were analyzed in terms of sensitivity, hysteresis, and repeatability. Experimental results showed that the proposed method can be suitable for the fabrication of air-gap sensors by using the roll-to-roll printed electronics technology.

Enhancement of mechanical properties of composites made of calcium carbonate modified bamboo fibers and polypropylene

Holzforschung ◽  
2015 ◽  
Vol 69 (2) ◽  
pp. 215-221 ◽  
Author(s):  
Haitao Cheng ◽  
Jie Gao ◽  
Ge Wang ◽  
Sheldon Q. Shi ◽  
Shuangbao Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aqueous Solution ◽  
Tensile Strength ◽  
Tensile Modulus ◽  
Inorganic Materials ◽  
Polypropylene Composites ◽  
Fiber Treatment ◽  
Bamboo Fibers ◽  
Properties Of Composites

Abstract The work aimed at the improvement of the mechanical properties of bamboo fiber-polypropylene composites (BaFPPC) by treatment of the fibers with CaCO3 at various concentrations of the solution (0.05, 0.1, 0.2, and 0.3 mol l-1). CaCO3 particles were successfully deposited in situ to bamboo fibers by means of ionic reaction of Na2 CO3 and CaCl2 aqueous solution at various temperatures. Then BaFPPC were produced, and various tests on single fibers and the composites were performed. The compatibility between BaF and PP matrix was improved by the treatments. The crystallinity of inorganic materials was significantly affected by the reagent’s concentration. A 10.4% increase in tensile strength and a 16.7% increase in tensile modulus were observed after fiber treatment with CaCO3 at a concentration of 0.2 mol l-1.

Porous Silicon as a Sacrificial Material for Microstructures Fabrication

1999 ◽  
Vol 605 ◽  
Author(s):  
M. Morel ◽  
M. Le Berre ◽  
V. Lysenko ◽  
G. Delhomme ◽  
A. Dittmar ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Electrochemical Etching ◽  
Sacrificial Layer ◽  
Formation Rate ◽  
Free Standing ◽  
Wide Range ◽  
Silicon Bulk ◽  
Reduced Costs ◽  
Optimized Conditions ◽  
Koh Etching

AbstractPorous silicon (PS) is generated by electrochemical etching in hydrofluoric acid (HF). Recently porous silicon has been applied to micromachining and micro-devices as an alternate material, this material being used as a sacrificial layer. This technology competes with conventional techniques like surface and bulk micromachining regarding its speed, simplicity and reduced costs. A wide range of microstructures and free-standing structures can be fabricated with a large freedom of design in relation to the isotropic behavior of the etching. A sacrificial layer may be realized fast over varying thickness (PS formation rate 45 μm/h compared to silicon bulk micromachining rate 20 μm/h for KOH etching).This contribution is devoted to the materials aspects of patterning and processing: we will show how basic microstructures (trenches, polysilicon cantilevers, polysilicon free-standing membranes) may be fabricated using a very simple process based on a single photolithography. The important points are the choice of the mask, porous silicon properties as a function of its formation parameters and the choice of the solution removing the sacrificial layer. The morphology and porosity of the porous silicon layers are indeed mainly determined by the electrolyte composition and by the current density for a given substrate type. Optimized conditions (HF 15% and 80 mA/cm2) lead us to an appropriate porous silicon. Finally the applicability of this technology for various microsensors will be underlined.

Synergistic effects of a novel free-standing reduced graphene oxide film and surface coating fibronectin on morphology, adhesion and proliferation of mesenchymal stem cells

2015 ◽  
Vol 3 (21) ◽  
pp. 4338-4344 ◽  
Author(s):  
Lin Jin ◽  
Zhiping Zeng ◽  
Shreyas Kuddannaya ◽  
Dan Yue ◽  
Jingnan Bao ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Surface Coating ◽  
Synergistic Effects ◽  
Chemical Reduction ◽  
Nanofiber Membrane ◽  
Free Standing ◽  
Vacuum Filtration ◽  
Reduced Graphene

Fabrication of free-standing reduced graphene oxide (RGO) films by vacuum filtration of graphene oxide aqueous solution through a nanofiber membrane in combination with chemical reduction.

A fabrication process based on structural layer formation using Au–Au thermocompression bonding for RF MEMS capacitive switches and their performance

2014 ◽  
Vol 6 (5) ◽  
pp. 473-480 ◽  
Author(s):  
Cagri Cetintepe ◽  
Ebru Sagiroglu Topalli ◽  
Simsek Demir ◽  
Ozlem Aydin Civi ◽  
Tayfun Akin
Keyword(s):  
Transmission Lines ◽  
Rf Mems ◽  
Mechanical Design ◽  
Sacrificial Layer ◽  
Fabrication Process ◽  
Worst Case ◽  
Micro Electro Mechanical Systems ◽  
Wave Measurements ◽  
Thermocompression Bonding ◽  
Structural Layer

This paper presents a radio frequency micro-electro-mechanical-systems (RF MEMS) fabrication process based on a stacked structural layer and Au–Au thermocompression bonding, and reports on the performance of a sample RF MEMS switch design implemented with this process. The structural layer consists of 0.1 µm SiO2/0.2 µm SixNy/1 µm Cr–Au layers with a tensile stress less than 50 MPa deposited on a silicon handle wafer. The stacked layer is bonded to a base wafer where the transmission lines and the isolation dielectric of the capacitive switch are patterned. The process flow does not include a sacrificial layer; a recess etched in the base wafer provides the air gap instead. The switches are released by thinning and complete etching of the silicon handle wafer by deep reactive ion etching (DRIE) and tetramethylammonium hydroxide (TMAH) solution, respectively. Millimeter-wave measurements of the fabricated RF MEMS switches demonstrate satisfactory up-state performance with the worst-case return and insertion losses of 13.7 and 0.38 dB, respectively; but the limited isolation at the down-state indicates a systematic problem with these first-generation devices. Optical profile inspections and retrospective electromechanical analyses not only confirm those measurement results; but also identify the problem as the curling of the MEMS bridges along their width, which can be alleviated in the later fabrication runs through proper mechanical design.

Curvature Evaluation of Si/3C-SiC/Si Hetero-Structure Grown by Chemical Vapor Deposition

2014 ◽  
Vol 778-780 ◽  
pp. 255-258
Author(s):  
Ruggero Anzalone ◽  
Massimo Camarda ◽  
Andrea Severino ◽  
Nicolo’ Piluso ◽  
Francesco La Via
Keyword(s):  
Sacrificial Layer ◽  
Chemical Vapor ◽  
Drift Region ◽  
Free Standing ◽  
Hetero Structure ◽  
Wafer Curvature ◽  
Transmission Electron ◽  
Standing Structure ◽  
Optical Profilometer ◽  
Si Films

In this work we analyzed the variation of wafer curvature due to the growth of thin Si layers on top of 3C-SiC/Si films. The final Si/3C-SiC/Si hetero-structure, allows not only to have a deeper understanding of the stress within the different layers, but can also be used for MEMS applications, using the Si film as sacrificial layer in order to obtain 3C-SiC free-standing structure, or for electronic application, e.g. using the thin Si layer as high quality MOSFET channel and the SiC layer as the drift region. In details, the influence on wafer curvature by the growth of thin Si layer on top on the 3C-SiC/Si film as been studied by optical profilometer. A theoretical model was also applied in order to fit the measured curvature of the hetero-structure and optimize the system. Finally, in order to study the morphology of the hetero-structure micro-Raman spectroscopy and Transmission Electron Microscopy (TEM) measurements has been performed.

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