New Sensors and Processing Chain E-Book

Nourdin Yaakoubi

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 178

Veröffentlichungsjahr: 2014

Beschreibung

A vital tool for researchers, engineers, and students, New Sensors and Processing Chain focuses on the processing chain to set up in order to extract relevant information on various systems. Highlighting the design of new microsensors and various applications, the authors present recent progress in instrumentation and microsystem design, providing insight to the modification of the sensor itself as well as its environment. Various applications illustrate the presentations, which show how a processing chain is organized from the data acquired by a specific sensor.

Leseprobe

Contents

Preface

1 Fabrication of Microelectrodes Using Original “Soft Lithography” Processes

1.1. Introduction

1.2. Materials and methods

1.3. Selective peeling process development and results

1.4. Localized passivation process development and results

1.5. Conclusions

1.6. Bibliography

2 Love Wave Characterization of Mesoporous Titania Films

2.1. Introduction

2.2. Love wave platform

2.3. Mesoporous materials

2.4. Environmental ellipsometric porosimetry

2.5. Experimental set-up

2.6. Numerical simulations

2.7. Causes of mechanical stress induced by humidity sorption

2.8. Conclusions

2.9. Bibliography

3 Immunosensing with Surface Acoustic Wave Sensors: Toward Highly Sensitive and Selective Improved Piezoelectric Biosensors

3.1. Introduction

3.2. SAW sensors and measurement systems

3.3. immunosensing applications to evaluate SAW device performances

3.4. Survey of clinical applications of SAW immunosensor systems

3.5. Conclusion

3.6. Bibliography

4 AC Nanocalorimeter on Self-standing Parylene Membrane

4.1. Introduction

4.2. Advantage of this type of microdevice

4.3. Nanocalorimeter for measuring nano objects

4.4. Device performances

4.5. Conclusion

4.6. Acknowledgments

4.7. Bibliography

5 Oscillatory Failure Detection in the Flight Control System of a Civil Aircraft Using Soft Sensors

5.1. Introduction

5.2. Modeling of the studied system

5.3. Design of a soft sensor for the oscillatory failure detection

5.4. Fault detection by standard deviation test

5.5. Fault detection by correlation test

5.6. Conclusion

5.7. Acknowledgments

5.8. Bibliography

6 Embedded Sensors for the Analysis of Drivers’ Behavior

6.1. Introduction

6.2. Trajectories’ observatory

6.3. The sensors’ network

6.4. Weather conditions

6.5. Analysis processing

6.6. conclusion

6.7. Acknowledgments

6.8. Bibliography

7 Large Deformable Antennas

7.1. Introduction

7.2. Mechanical analysis

7.3. Optical instrumentation for deformable antennas

7.4. Experience on a planar structure

7.5. conclusion

7.6. Acknowledgments

7.7. Bibliography

List of Authors

Index

First published 2014 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

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© ISTE Ltd 2014The rights of Jean-Hugh Thomas and Nourdin Yaakoubi to be identified as the authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Control Number: 2014947783

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A CIP record for this book is available from the British Library

ISBN 978-1-84821-626-6

Preface

Extracting information on a system is required to understand its state, to describe its behavior and to predict its early damage in order to be able to undertake the necessary corrective actions. The essential mechanism for data acquisition is the physical sensor, which can be electronic, chemical, biological, mechanical, acoustic, etc. For some years, the sensor environment has been changing. The sensor has become a central part of a more complex process that operates as a team, communicates, takes decisions and is able to diagnose the state of the system under surveillance. Hereafter, the sensor is in charge of several tasks, getting smaller and smaller, sharing information with other sensors in a communication network. The instrumentation chain, the processing chain and the decision-making process can be seen as a software sensor. This evolution of the sensor is noticeable in many fields as shown by the various conferences on the subject around the world.

The chapters proposed here reflect the abundance of work about instrumentation, from the sensor, often miniaturized, to the diagnosis.

Sensor miniaturization provides a gain in volume and mass for an increase in processing power, but requires high-precision manufacturing. For microsystem engineering, it is essential to have an expert knowledge of the materials and to work on the development of new technology addressed here such as thin film layer deposition, lithography and “soft lithography”. The latter is illustrated here with the aim of developing localized metallization processes for the microfabrication of electrodes to be used in electrochemical biosensors. The control of materials, technology and microsystem reliability is very useful to ensure the proper functioning of the device, which also requires the development of characterization techniques. An example of microfabrication coupled with an original measurement device is given here for a highly sensitive ac-calorimeter. The characterization of the shear modulus of a mesoporous titania film, combining a Love wave sensor with environmental ellipsometric porosimetry is the subject of another chapter. In addition, readers will be able to notice the advantages of miniaturizing, in the framework of biosensors, called gravimetric surface acoustic wave (SAW) sensors specialized in biological particle recognition.

The improvement of functional safety is of major concern, particularly in the case of the flight control process of an aircraft. Readers will see how oscillatory failures on the control system are detected from comparisons between signals acquired by physical sensors and data provided by several models of the flight behavior of the aileron of the aircraft.

The automatic surveillance of roads is also taking advantage of the sensor evolution. Thereby, a network of optical and resistive sensors, linked by the same communication bus, embedded in the road, makes possible the analysis of the trajectories followed by the drivers.

The ingenuity of radar antennas highlighting a limited mechanical structure complexity, deformed and dynamically compensated, will grab the reader’s attention. The surface distortions are measured from optical sensors based on fiber ribbons or polarization rotation and used to feed algorithms compensating the radiation patterns of the antenna subjected to deformation.

Jean-Hugh THOMASbr/>Nourdin Y>AAKOUBIAcoustics Laboratory at the University of Maine –LAUM UMR CNRS 6613National School of Engineers of Le Mans – ENSIMSeptember 2014

1

Fabrication of Microelectrodes Using Original “Soft Lithography” Processes

1.1. Introduction

Nowadays, there is a significant need for low-cost analytical tools that are capable of giving fast and accurate detection for environmental and medical applications. Downsizing devices is the main answer to this issue. It permits a high analysis throughput as well as both a decrease in sample and reactant consumption and a decrease in the instrumentation cost.

The most widely used technology, at the present time, for downsizing devices is photolithography [BRA 94]. A photosensitive resin is spin-coated onto the substrate surface, which is then irradiated through a mask using ultraviolet (UV) light. Whether the resin technology is positive or negative, the irradiated regions or the non-irradiated regions are removed using a developer. Metallic microstructures can be obtained using sputtering and lift-off. This technology makes possible the mass production of micrometric and sub-micrometric structures. However, this technology is not low cost because of the requirement for clean room facilities and high-tech equipment. In addition, this technology is not suitable for non-planar surfaces and it is only applicable on photosensitive materials (e.g. photoresists).

A new type of substrate patterning, known as soft lithography [XIA 98], and more especially microcontact printing, has been developed by Professor Whitesides’ team. A soft elastomeric stamp (typically made from polydimethylsiloxane (PDMS)) with a relief structure is used to transfer it onto the substrate surface. In the microcontact printing (μCP) technique, the stamp is “inked” with a chemical solution and is then put into close contact with the substrate surface [XIA 98]. The stamp is peeled off and the surface is then patterned with the “ink”.

The most popular application of μCP is the transfer of an alkanethiol as “ink” onto a gold surface [KUM 93]. Alkylthiols form a self-assembled monolayer (SAM) at the surface that protects gold from chemical etching. Whitesides’ team has demonstrated that using this technology, patterns with characteristic features down to 30 nm can be achieved. Furthermore, this technology is of low cost. Whether the substrate is planar or not [JAC 95], various types of substrates can be used (e.g. silicon [XIA 95], glass [GEI 03] and polymer [HID 96]), and depending on the chemical function at the end of the alkyl chain, various surface chemistries can be obtained.

Our work aims at developing original localized metallization processes for the microfabrication of electrodes to be used in electrochemical biosensors. This technology is applied on polymer [BES 09] or glass substrates (work presented here). Two original processes using alkanethiol μCP are described: the first process consists of a selective peeling of the metal thin-film areas not protected by the SAM, which makes it possible to avoid any chemical etching step in the process; the second process consists of passivating, with the help of a SAM, a gold electroless catalytic coating deposited on the substrate, which makes it possible to trigger localized growth of the metal and to avoid the need for a homogeneous gold thin film deposited using Physical Vapor Deposition (PVD) onto the substrate surface.

1.2. Materials and methods

1.2.1. Selective peeling

For the selective peeling process, glass substrates coated with gold thin films were used. The thin film was deposited using PVD cathode sputtering (EMSCOPE SC 500). To improve the practical adhesion of gold to the glass substrate, a thin layer of silver nanoparticles was first deposited. More precisely, microscope soda-lime glass slides (Roth-Sochiel, Lauterbourg, France) were cleaned in a piranha solution (3:1 mixture of H2SO4 96% and H2O2 30%) at 130°C for 30 min. Glass slides were then rinsed in ultrapure water (MilliQ, Millipore) and dried under a continuous flow of nitrogen.

The thin layer of silver nanoparticles was prepared directly on the glass slide by successive immersion in a 4% KOH solution, a 0.2 g.L–1 SnCl2 solution and, finally, a 10 g.L–1 AgNO3 solution. Between each immersion, substrates were rinsed in ultrapure water. After drying under a continuous flow of nitrogen, substrates were metallized using PVD cathode sputtering. The thickness of the thin film was estimated to be about 20 nm following abacus.

For the selective peeling process, a monolayer of octadecanethiol was deposited by microcontact printing on the gold-coated substrate surface. To ensure this step, the PDMS stamp was stored in an ethanol solution of octadecanethiol (2 mM). After the octadecanethiol deposition, a glass substrate with adhesive on top (UHU glass adhesive, containing 2-hydroxyethylmathacrylate) was deposited onto the modified substrate. The two substrates were pressed to make possible the spreading of the adhesive along the whole area. The glass slides were then irradiated for 10 min under a UV lamp to ensure polymerization. After cooling, the glass slides were removed. On the gold coating side, areas not protected by the SAM were peeled off but removed gold parts exhibit the original pattern on the slide with the adhesive layer.

1.2.2. Localized passivation

Cleaned glass substrates (see section 1.2.1) were surface modified with 3- aminopropyltriethoxysilane (APTES) in order to obtain amino groups at the substrate surface. More precisely, substrates were immersed in a 1% APTES solution in methanol for 45 min. Substrates were then rinsed in methanol, ultrapure water and finally dried under a continuous flow of nitrogen.

The gold electroless catalytic coating was obtained by adsorbing gold nanoparticles on the amino groups at the substrate surface. For this matter, substrates were immersed in a gold nanoparticle solution for six hours. This catalytic coating was then passivated by octadecanethiol microcontact printing (2 mM ethanol solution).

For silver electroless metallization, the solution was prepared by mixing 0.5 g of AgNO3, 0.02 g of SnCl2, 31 mL of ultrapure water, 19 mL of ammonium hydroxide (25%) and 40 μL of formaldehyde. The solution was used at ambient temperature and metallization took place for 5 min.

1.3. Selective peeling process development and results

In the conventional microcontact printing process applied to gold substrates (Figure 1.1), localized SAM of octadecanethiol protects the substrate from chemical etching. Thus, microstructures are obtained by selective etching of unprotected areas. However, chemical etching necessitates the use of toxic solutions.

Figure 1.1.Principle of conventional microcontact printing of alkanethiol to protect the gold layer from chemical etching

In the first original process presented in this chapter (Figure 1.2), microcontact printing is used to obtain a localized monolayer of octadecanethiol. Unlike the conventional process, the gold layer is not etched but peeled off using an adhesive. Indeed, the SAM exhibiting a compact form prevents the adhesive from bonding to the gold layer. For unprotected areas, the adhesive sticks to the metal layer. To remove the adhesive, it is proposed to use a glass substrate that will also strongly stick to the adhesive. During the separation step, the bonding strength between the glass and the gold layer not covered by the octadecanethiol SAM is weaker than the bonding strength between the adhesive and the gold monolayer; thus, the latter will be peeled off.

Figure 1.3 shows an example of microstructures that can be obtained with the selective peeling process. The inset shows a close-up of the photographs and demonstrates the process feasibility for micrometric patterns (estimated smallest width about 60 μm).

Figure 1.2.Principle of the selective peel-off process

Figure 1.3.Picture of an interdigitated electrode system obtained using the selective peel-off process applied with a gold thin layer and an alkanethiol self-assembled monolayer

1.4. Localized passivation process development and results

In the localized passivation process, the aim is to grow a localized layer of electroless silver. Electroless metallization (Figure 1.4) is based on a reaction between ions from the metal to be deposited and a chemical reducer, both being mixed in the same bath. The bath must be stabilized by the use of a complexing agent to limit spontaneous reduction of metal ions. Upon contact with a catalytic substrate surface (e.g. gold nanoparticles), reaction takes place and hence there is metal deposition specifically on this surface.

Figure 1.4.Electroless metallization principle at the interface of a substrate coated with gold nanoparticles that are catalytic to silver electroless metallization

The principle of the original process described in this chapter (Figure 1.5) consists of coating the whole surface of a glass substrate with a layer of gold nanoparticles that are catalytic to silver electroless metallization. In order to grow a localized silver electroless layer, octadecanethiol microcontact printing is used to passivate the catalytic layer. The octadecanethiol monolayer at the nanoparticle surface makes it possible to avoid any chemical etching at the surface. Thus, a silver deposit is obtained only in areas not protected by the SAM of octadecanethiol.

Figure 1.5.Principle of the localized passivation process developed in this work

Figure 1.6.Picture of a set of interdigitated electrodes obtained using the localized passivation process described in Figure 1.5

Figure 1.7.Picture of a microelectrode obtained using the localized passivation process described in Figure 1.5. The smallest width is 60 μm

Figure 1.6 shows an example of a set of interdigitated electrodes obtained using the localized passivation process based on a layer of gold nanoparticles, SAM localized deposition followed by silver electroless metallization. The pattern exhibits the smallest width dimension of about 300 μm. The same process was used to obtain electrodes exhibiting the smallest width of about 60 μm, as can be seen in Figure 1.7. It demonstrates the ability of this process to reproduce micrometric scale patterns.

1.5. Conclusions

Due to soft lithography and especially due to microcontact printing, two original processes making it possible to replicate microelectrodes were successfully developed.

In the first process (selective peeling process), an adhesive was used to reveal the patterns obtained using microcontact printing, which makes it possible to avoid any chemical etching step.

In the second process (localized passivation process), microcontact printing was used to obtain a localized passivation of a catalytic layer (gold nanoparticles), which makes it possible to obtain a localized silver electroless layer.

1.6. Bibliography

[BES 09] BESSUEILLE F., GOUT S., COTTE S., et al., “Selective metal pattern fabrication through micro-contact or ink-jet printing and electroless plating onto polymer surfaces chemically modified by plasma treatments”, The Journal of Adhesion, vol. 85, no. 10, pp. 690–710, 2009.

[BRA 94] BRAMBLEY D., MARTIN B., PREWETT P.D., “Microlithography: an overview”, Advanced Materials for Optics and Electronics, vol. 4, no. 2, pp. 55–74, 1994.

[GEI 03] GEISSLER M., KIND H., SCHMIDT-WINKEL P., et al., “Direct patterning of NiB on glass substrates using microcontact printing and electroless deposition”, Langmuir, vol. 19, no. 15, pp. 6283–6296, 2003.

[HID 96] HIDBER P.C., HELBIG W., KIM E., et al., “Microcontact printing of palladium colloids: micron-scale patterning by electroless deposition of copper”, Langmuir, vol. 12, no. 5, pp. 1375–1380, 1996.

[JAC 95] JACKMAN R.J., WILBUR J.L., WHITESIDES G.M., “Fabrication of submicrometer features on curved substrates by microcontact printing”, Science, vol. 269, no. 5224, pp. 664–666, 1995.

[KUM 93] KUMAR A., WHITESIDES G.M., “Features of gold having micrometer or centimeter dimensions can be formed through a combination of stamping with a elastomeric stamp and an alkanethiol “ink” followed by chemical etching”, Applied Physics Letters, vol. 63, no. 14, pp. 2002–2004, 1993.

[XIA 95] XIA Y., MRKSICH M., KIM E., et al., “Microcontact printing of octadecylsiloxane on the surface of silicon dioxide and its application in microfabrication”, Journal of the American Chemical Society, vol. 117, pp. 9576–9577, 1995.

[XIA 98] XIA Y., WHITESIDES G.M., “Soft lithography”, Annual Review of Materials Science, vol. 28, pp. 153–184, 1998.

Chapter written by Stéphane COTTE, Abdellatif BARAKET, François BESSUEILLE, Stéphane GOUT, Nourdin YAAKOUBI, Didier LEONARD and Abdelhamid ERRACHID.

2

Love Wave Characterization of Mesoporous Titania Films

2.1. Introduction

In the last few years, mesoporous oxides have achieved a strong development due to their specific properties such as high active surface (150 to 1,000 m2/cm3), adjustable porosity (suitable for particles and species molecular trapping) and wide functionalizing and structuring possibilities [SAN 08]. Therefore, mesoporous oxide films have raised much interest for chemical sensor design [TIE 07].

In particular, Love wave sensors (guided shear horizontal surface acoustic wave) coated with mesoporous sensitive layers have shown good sensitivity and short-time response for volatile organic compounds (VOCs) [TOR 09] and heavy metal detection [GAM 14].

Parameters of the material may differ during vapor sorption, such as rigidity, viscoelasticity or permittivity. These properties must be characterized and modeled accurately to improve microsensor design. The literature provides little information about these nanostructured materials, especially when they are used in high frequencies. Note that mechanical properties of thin films, such as density and stiffness, strongly depend on their fabrication and deposition processes [CAR 02]. Therefore, it is important to consider the films in their real operating conditions.

Several characterization techniques are commonly used for the characterization of Young’s modulus, such as Brillouin light scattering [CAR 05], nanoindentation [GAI 09], or micro-traction [TAN 10]. However, they are difficult to carry out under humidity exposure.

Thus, a dedicated experimental set-up developed for the characterization of film shear modulus is presented in this work. It combines a Love wave sensor with environmental ellipsometric porosimetry.

Environmental ellipsometric porosimetry is generaly used to characterize mesoporous materials and presents many advantages [BOI 05]. In particular, measurements are performed in situ and are non-destructive. Young’s modulus is calculated at the sorption cycle end and it corresponds to the fully hydrated film. Acoustic waves are used to determine film shear modulus throughout the sorption cycle.

In section 2.2, we describe the Love wave device. Then, mesoporous materials and environmental ellipsometric porosimetry (EEP) are described. The experimental device, combining acoustic wave and EEP, and the results will be presented. Simulations of Love wave propagation have been performed and shear modulus variations of a mesoporous titania film have been determined with a maximum variation of 2.1 GPa during the desorption. Finally, the possible explanations of this nonlinear reponse have been discussed, regarding the porous nature of the film and its specific fabrication process.

2.2. Love wave platform

The Love wave sensing principle is based on the perturbation of a guided shear horizontal surface acoustic wave.

The device consists of an AT cut quartz piezoelectric substrate (0°; 121.5°; 90°) allowing horizontal transverse polarization of acoustic waves. The Ti/Au interdigitated transducers (IDTs) consists of 44 split finger pairs with a 40 μm periodicity (λ) ensuring the wave generation. The acoustic path length (between the two transducers) is 164 λ. A 4.5 μm SiO2 guiding layer was deposited on the top of the quartz substrate in order to generate Love waves and to confine the acoustic energy [ZIM 01]. Adding a sensitive layer on the propagation path enabled the sorption of molecules (Figure 2.1) ensuring both amplification effect and possible specificity. The sorption modifies the physicochemical properties of the sensitive layer, which are measured through the phase velocity variations.

Figure 2.1.Love wave sensor

For high-resolution experimental measurements, the Love wave delay-line is inserted in the feedback loop of an amplifier in order to achieve an oscillator system. The real-time measured frequency shifts are linked to the wave velocity shifts (Figure 2.2).