Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A new method for the design and manufacture of sensors based on optic fibres

25.04.2003


A novel method for the design and manufacture of sensors to measure the temperature and relative humidity of the air, the pH of solutions or the refractive index of liquids based on optic fibre has been devised at the Public University of Navarre.



The sensors are small devices capable of capturing both physical and chemical signals from the surrounding environment and converting them into electrical signals for their subsequent processing. The information thus transformed can be easily quantified, manipulated and processed by electronic and computer systems which keep us constantly up-dated on any change in the environment where the device is located.

In this PhD thesis, the proposed sensors are based on the transformation of the optic fibre by a burnished area thereof. These optic fibres are of standard telecommunications monomode silica and their coating has been partially eliminated over a small area by mechanical burnishing. This perturbation on the burnished zone alters the propagation of the optic signal transmitted in the fibre, giving rise to a controllable correlation between the diminution of the optic potential of the outgoing signal and the mesurando which actuates with the signal over the said transformated zone.


The impact of the perturbation to which the fibre is subjected with the burnishing varies according to the samples. In some, the perturbation is important, in such a way that an amply dynamic range can be achieved for the sensor more than half of its power. This depends on the extent of the burnishing.

Sensors for turbidity and composition

Using this sensor system, the thesis author, Ainhoa Gastón, has studied the optic structure based on this polished fibre, its characteristics, how it changes the transmitted potential, i.e., what the light intensity might be as a function of parameters such as wavelength and external refraction index in contact with the structure, in order to know how to interpret what the sensors’ characterisation curve might be.

This research and the suitable selection of materials have provided the guidelines for the development of the sensors presented and, likewise, constitute a simple procedure for the design of new sensor devices adapted for specific applications.

One of the applications of the new sensors is the study and determination of the refraction index of liquids, in other words, functioning as a refractometer, with the advantage, moreover, of being not only incorporated into the fibre, but also being able to provide the index of non-transparent materials.

Thus, in a process of chemical components manufacture, the sensors allow the exact measurement of what will be, in the end, the refractive index, and in such a way that it will be possible to determine the chemical composition from the data obtained. For example, using a sensor incorporated into a tray on a production line, exactly what is being mixed when different compounds are being mixed can be determined in situ, or the concentration of sugar in a solution can be controlled. This application is useful not only for food processing but also all kinds of chemical processes.

In the same way, the refractive index allows the determination, for example, when the water in a washing machine gets so dirty that it has to be changed. In this sense, although this application is carried out by means of sensors for turbidity, it can equally be effected using the refractive index of the water when it becomes darker and/or dirtier. In this case, the sensor head would have to be incorporated inside the washing machine drum and, via optic fibre, the information on turbidity, etc., would be transmitted directly to the control panel of the washing machine, to the microprocesser which integrates all the functions.

In brief, the sensors designed in this PhD thesis serve to incorporate them into certain networks for controlling conditions such as humidity, temperature, pH, the quality of oil, etc. They can be used in very specific situations, in those cases where other sensors are not viable, in effect, both their operation and resistance characteristics are very good. Moreover, it is important to take into account the current ubiquity of optic fibres, given that the use of these sensors does not require electro-optical transducers in order to obtain the information they offer.

Method of manufacture

The polishing techniques currently used to make the sensors are varied. For example, there are those who polish the fibres incorporated into silicon wafers or glass blocks. The method proposed by Ainhoa Gastón, however, is one where the fibre is polished trapped in a resin, given that it is a much cheaper alternative, much more accessible, even versatile, given that the resin allows the moulding of pellets of varying sizes, with a bigger or smaller curvature of fibres embedded in them. Apart from the resin, this PhD proposes the use of other new materials aluminium powder (aluminium oxide) as an abrasive element.

Likewise, Ainhoa Gastón puts forward an innovative system of moulding of the fibre in multiple stages. One of the peculiarities of this system is that it permits placing different curvatures at different points on the fibre.

Garazi Andonegi | Alphagalileo
Further information:
http://www.basqueresearch.com

More articles from Process Engineering:

nachricht Intelligent wheelchairs, predictive prostheses
20.12.2017 | Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA

nachricht Jelly with memory – predicting the leveling of com-mercial paints
15.12.2017 | Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>