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Ingeniare. Revista chilena de ingeniería

versión On-line ISSN 0718-3305

Ingeniare. Rev. chil. ing. v.18 n.3 Arica dic. 2010

http://dx.doi.org/10.4067/S0718-33052010000300001 

Ingeniare. Revista chilena de ingeniería, vol. 18 Nº 3, 2010, pp. 274-279

                                                                       ARTICLE EDITORIAL

 

SYSTEMS OF NANOSENSORS FOR SMART MATERIALS 

In the National Center for Metallurgical Research (CENIM), integrated in the CSIC organization (www.csic.es) of Spain, a group of researchers works investigating and developing a family of nanosensors (very small collector items of variations in material and developed with nanotechnologies) which are embedded in non metallic materials, in order to obtain data of their behavior before diverse outer stimuli. Then, the information is transmitted to a system in charge of the management of these events. This technology (pioneering the so-called "smart materials", which are an important innovation in the science of materials) opens the possibility to get information in real time about the behavior of the material to diverse unforeseen contingencies.

This article describes the development that this research is taking, within our work group, the fields of application of these developments in engineering of materials, as well as the ultimate aims, achievements, the possible sources of financing to continue the investigation in the next future, and the areas where major impacts of results are expected.

Many traditional materials, of metallic composition, are being replaced by materials made with "composites" materials and resins. Inside this type of materials it is possible to install nanosensors that can inform what happens in the material in case of fatigue, collision, extreme variations of temperature, etc.

Antecedents
The metallic materials can be replaced advantageously by synthetic materials of the same physical characteristics, but with mechanical and economic advantages, that will be discussed later. This substitution, which has been doing for years, is a trend that will continue to evolve in the coming years. Our innovation in this field is to equip the material with intelligence, according to the description of this article.

New "composite" materials
Our interest is aimed at the industrial production of new smart materials applied, in principle, to the fields of Defense, vehicles and aircrafts. In the future, we expect to use this technology in other civil fields, and it could be extended to more areas of industrial application.

We are focused on the investigation and development of structures of materials of "sandwich" type, which are made on the base of "composites", with a central metallic mesh that gives consistency to the piece. "Composite" is almost all the set that we will denominate "structure", which corresponds to the piece equipped with all its components. The structure is finished with metallic coating. Figure 1 shows the composition of these structures of "sandwich" type, with a central metallic mesh, embedded in the "composite", and it is what forms the base of our investigations, in the compound materials area.

In these structures of new materials, a set of nanosensors and an electronic device will be installed in order to obtain data generated by the sensors, which will allow knowing in real time what happens in the material, before any contingency.

Components of the system of sensors
For researchers, this system introduces a major innovation in the new smart materials and has the following philosophy in terms of the components used in it:

  • Nanosensors of elastic type, which catch deformations and transmit them to a micro optical system.
  • Nanosensors of seismic type, to catch blows and vibrations.
  • The use of a microelectronic system to transmit data.
  • The use of optical nanofibers to transmit data.

All these elements are embedded in the "composite" material itself.

Externally there is a receiver of the data that also performs the data processing, in order to give coherent information to the user. The sensors and microelectronics are fruit of our investigations and developments, altogether with the piece of compound material. All these are what we denominated "smart material" or smart structures.

State-of-the-art
This section briefly describes the current level of development in this area of knowledge, from different industries and research centers.

The car manufacturing, aeronautics and construction industries, have been investigating for a long time the use of new materials to replace, even in a partial manner, the traditional metallic materials.

These new materials have a number of advantages, as listed below:

  • Lower weight than the traditional materials.
  • Lower cost than other commonly used materials.
  • Greater resistance than other materials.
  • Greater ease of recycling material at the end of its life, with the advantage of an easy way to recycle and comply with the rule of the European Union (EU), which requires from 2.015 to recycle 95% of disposable material, at the end of its useful life.

In France there are projects of this type for the naval industry, in the USA for the aeronautics industry and in Spain for the car industry. This shows the industrial interest that is awakened by this type of materials and its application.

At the moment it is getting this substitution gradually, but it is expected to add improvements in certain applications, to transform the material into smarter, and increase the benefits of using these materials intensively.

This kind of improvements, always adapted to the future use of the material, is under investigation, because of the relevance that its application has in the area of engineering, in each of the areas where it is used.

The basis of our current research can be found in the achievement of the following:

  • The development of laminated plates with laminated mesh based on deformation theory.
  • Simulation algorithms to measure the resistance of the material.
  • Fatigue Test.
  • Ecological manufacturing.

Objectives
Our research aims to achieve the following objectives:

  • To investigate structures of "composite" materials containing inside a metal mesh to provide resistance to the material. This mesh can be copper, steel, aluminum or any alloy, according to the application that the material in question and its composition is used, which is a part of the investigation.
  • To determine the most suitable metal plates to cover the structures on both sides, which are what give them their special finish.
  • To investigate and develop a set of nanosensors to be installed, embedded within the material, to acquire data, with all the associated electronics and optical nanofibers that allow the transmission of data.
  • To develop an embedded micro transmitter, responsible for sending data outside of the structure.

Structures of material

The structures that are being investigated are sandwich type, as it has been already mentioned, with a similar aspect to the ones in Figures 1 (used mesh) and 2.

 

 

 

 

Figure 1. Interior mesh.

Figure 2.Sandwich structure.

In Figure 1 it is possible to see a metallic mesh, from those used in our research. In Figure 2 we have the practical plan of how to make a structure of "composites" with a mesh-shaped metal honeycomb. On these structures we develop our research and try to achieve the objectives.

Nanosensors
Nanosensors that will be installed inside the structure, will interconnect with the use of fiber optics, working in transmission and reception, i.e., two fibers are used for interconnection, as shown in Figure 3.

In Figure 3, the sensomicro transmitter that will send the information.

 

 

 

 

Figure 3. Connection of nanosensors.

Figure 4. Micro transmitter.

Microtransmitter

All the fibers will be connected to an electronic micro device which objective is to transmit these data to an external system, using a micro transmitter, such as the one presented in Figure 4.

This micro transmitter takes advantage using the metal deck of the "sandwich" as an antenna. The transmission tests are performed in FM (frequency 2,432 MHz) and in compatible frequencies with devices WI-FI (2 to 6 GHz), to determine which of the systems allow more range with less consumption. We seek a minimum range of 50 m and 100 m. desirable. Another line of research is related to how efficiently perform the external energy input, needed to make the system work properly.

External reception

The external transmitting receiver is the one in charge to receive the data, counting with the software, developed in the project to treat them. For that, algorithms will be implemented, that allow predetermining damages in collisions, effect of temperatures, vibrations, etc., from the information coming from the sensors and what happens in the material. This application is very important in the aeronautics, defense areas, construction and car industry. Software is developed in JAVA language.

Basically this system of reception consists of a transceiver suitable to the frequency that is being used, and a microprocessor with its memory to contain the application software. In the user display appears the information of the system, adapted to the operating form of the controller. This external system does not have to be miniaturized, because it is totally external to the material and of conventional nature.

Conclusions

The experimental development carried on by our group, has been made in several successive phases that are described as follows:

  1. Obtaining a set of structures, not yet intelligent, made with "composites" and resins, which are suitable for the purpose intended.
  2. Research and development of the metallic mesh that will be used, so as to enable a consistency suitable for industrial application of the structure.
  3. Research and development of nanosensors that will be used. This is the most difficult stage, since the sensors are extremely small and must have a useful lifespan, so as to do not invalidate their role prematurely. We seek in principle a one-year life, time that is expected to be expanded. Nanosensors have a code that identifies them and an optical transducer which allows, when questioned, to send the information to electronic data collection. The connection of the sensors with the data collection center inside the material is multipoint, via optic fiber, as indicated.
  4. Selecting the most appropriate optical nanofibers to be used in the structure. For each type of industrial application, the kind of optical fiber used is different.
  5. Electronics research associated with the set of nanosensors, development of the unit and the operating software.
  6. Research and development of radiating system, which is a type of microtransmitter presented above and its connection to the external structure to act as an antenna and can send data to the receiver. We investigate the directionality of the transmitter to exploit the maximum energy, and the most suitable frequency for transmission.
  7. External power of the electronic system. This point is very important since it must ensure a reliable and economic operation of the embedded system.
  8. Installing the set of sensors and electronic in material, in the most appropriate way for the proper functioning, in the most optimal possible conditions.
  9. Development of a battery of tests to verify the results obtained, according to the predictions of the investigation.

We have to indicate that all the processes are carried out following a quality plan framed in ISO 9000.  

Practical example of experimental application

In this section we want to exhibit a concrete structure, performed as an experimental development, according to the described methods, that works as element of tests and that will have a concrete industrial application later.

As an example of what we have made, we can present/display the development of a structure applied to a UAS (Unmanned Aerial System), also known as UAV (Unmanned Aerial Vehicle). These types of vehicles are getting a high utility in military as well as in civil applications (monitoring of borders). As a research team, we considered that the demand in the industry of these structures goes in crescendo, which gives an interesting added value, which is why we insist on the development of that structure.

Figure 5. UAS.

Figure 5 is an example of UAV in a span of 1.62 m, which can be perfectly used for our tests.

80% of its structure would consist of structures of the type we have described in previous sections.

The usefulness of this UAV would be focused on border control, taking an engine, steering, fuel compartment and another compartment with electronic instrumentation (video cameras and sound sensors).

In this test the autonomy of the UAV and its equipment is not part of our interest. We study how the material responds and how the sensor system is capable of obtaining good data, process it and send in real-time to the data capturing system.

The system is reusable. In principle it is equipped with four seismic nanosensors, five elastics and an optical system for data collection. This data is sent via a miniature FM transmitter to the outside for its processing in the monitoring system. In this way, the structure is submitted to different processes and we can see if the sensor system registers the data with the required fidelity and if it is able to transmit it to the controller.

This model works well to pass the test bench developed during the investigation and to verify experimentally the developments made.

Summary of obtained results

So far, we have obtained the following results:

This team considers that 40% of the proposed objectives have been achieved.

Future research

In the near future we want to achieve results for the aircraft and automobiles, important industries, which can be largely benefited by this technology.

The objectives that we set are related to obtain financing to expand the goals of the project, introduce in the field of aero structures and automation.

Procedures of financing

In order to achieve our objectives, we needed greater financing and a cooperative work with other groups of investigation. We want to obtain it by means of a project of VII Program Frame of the European Union.

For that reason we have created a partnership of associates who work in similar lines of investigation, presenting/displaying to the European Union a proposal called NESBE, with the objective to ask for financing in order to be able to continue these investigations, applied to the industry.

In the chart we indicate the European institutions of investigation that participate in this partnership.

 

Number

Organization

Country

Type of organization

Acronym

1. Coordinator

Agencia Estatal Consejo Superior de Investigaciones Científicas

Spain

National Research Center

CSIC

2

Baris Elektrik S.A.

Turkey

SME

BAR

3

Technological Institute of Optics, Colour and Imaging

Spain

Research Center

AIDO

4

FADA-CATEC Center for Advanced Aerospace Technologies

Spain

Research Center

CATEC

5

Riga Technical University

Latvia

University-Research Center

RTU

6

HLP DEVELOPEMENT S.L.

France

SME

HLP

7

TROYKA LTD

Turkey

SME

TRO

8

University of Chemical Technology and Metallurgy

Bulgaria

National Research Center-University

UCTM

9

Tampere University of Technology

Finland

University-Research Center

TUT

10

Centro Ricerche FIAT S.C.p.A. (CRF)

Italy

Research Center

CRF

11

SINTEF Group

Norge

Research Center

SIN

Impact

We expect a significant impact of these investigations and developments, in the following areas:  

 

PhD. Manuel Rincón Arche
CENIM-CSIC
España
E-mail: mrincon@cenim.csic.es

PhD. José Antonio Robla
CENIM-CSIC
España