Micro Machined Optical Fibers

Fiber-optic Sensors for the Monitoring of Liquid Mixtures

Optical Engineering, Feb. 26, 2014Eyal Preter,1 Vlada Artal,1,2 Chaim N. Sukenik,2 and Avi Zadok1,*1Faculty of Engineering, Bar-Ilan University, Israel2Departmaent of Chemistry, Faculty of Exact Sciences, Bar-Ilan University, IsraelAvinoam.Zadok@biu.ac.il

1How to monitor Evaporation?Traditionally:Direct observation: contact angle GoniometerAFM cantilevers Micro Gravimetry

AccuracyComplicated SetupLimited accessibility

2Dr. Avi Zadok, Bar-Ilan Univ. Feb. 20142ObjectiveSimple, low-cost fiber-optic sensor for monitoring the evaporation of liquids

Proof of conceptEvaporation-related dataComparing with traditional methodsApplications

3Dr. Avi Zadok, Bar-Ilan Univ. Feb. 20143The Setup

LaserFiber Tip ResonatorCirculatorPowerMeterScope

The Sensor: Cleaved FiberThe Input: Fixed Laser SourceThe Readout: Low Bandwidth Detector & Scope.

4Dr. Avi Zadok, Bar-Ilan Univ. Feb. 20144Principle of OperationLight is launched from the remote end of the fiber, and the reflected power is monitoredLight is reflected at the fiber / liquid interface, and the liquid / air interfaceThe two reflections combined create interference, according to the thickness of the liquid dropletAs the liquid evaporates, interference fringes are observed:

5Dr. Avi Zadok, Bar-Ilan Univ. Feb. 2014

5Typical Results: Raw Data

Water

6Dr. Avi Zadok, Bar-Ilan Univ. Feb. 20146Typical Results: Instantaneous Droplet LengthWater

7Dr. Avi Zadok, Bar-Ilan Univ. Feb. 20147Control Experiment

8Dr. Avi Zadok, Bar-Ilan Univ. Feb. 2014Control Experiment

9Dr. Avi Zadok, Bar-Ilan Univ. Feb. 2014Apps (1): Mixtures StudyEthanol Concentration In Water

10Dr. Avi Zadok, Bar-Ilan Univ. Feb. 201410Apps (1): Mixtures StudyEthanol Concentration In Water

11Dr. Avi Zadok, Bar-Ilan Univ. Feb. 201411Apps (2): Recognition of solvents: bare fiber tip Difficult to categorize 10 solvents based on evaporation time and droplet size alone

12Dr. Avi Zadok, Bar-Ilan Univ. Feb. 201412Surface ModificationSurface treatmentDeposition of single layer (monolayer) hydrophobic coating.The monolayer does not interact with the light, but changes the surface behave.

Normal FiberCoated Fiber

13Dr. Avi Zadok, Bar-Ilan Univ. Feb. 2014Surface Modification

DynamicsBare FiberCoated Fiber

14Dr. Avi Zadok, Bar-Ilan Univ. Feb. 2014Evaporation from modified surfacesAcetone

15Dr. Avi Zadok, Bar-Ilan Univ. Feb. 2014

Droplet length on coated fiber: relation with polarity index 16Dr. Avi Zadok, Bar-Ilan Univ. Feb. 2014

Apps (2): Recognition of solvents: coated fiber tip Evaporation from coated fibers can distinguish between all 10 solvents through simple data analysis

17Dr. Avi Zadok, Bar-Ilan Univ. Feb. 201417Apps (2): Recognition of solvents: combined analysisSolvents recognition based on the combined analysis of evaporation from both bare and coated fibers

18Dr. Avi Zadok, Bar-Ilan Univ. Feb. 201418Apps (3): Recognition of flexible fuel blends19

A Flex Fuel Sensor is a device that measures the ethanol content in the cars fuel system. The sensor is installed between the fuel pressure regulator and the fuel tank, where it monitors the ethanol content of the fuel returning to the tank.The information is then passed onto the system which applies fuel, ignition and boost corrections. The system allows the driver to add any mixture of ethanol/petrol (from 0-100% ethanol content).Dr. Avi Zadok, Bar-Ilan Univ. Feb. 2014Apps (3): Recognition of flexible fuel blendsA large number of flexible-fuel vehicles in the US are equipped with an in-line sensor for reading the contents of alcohol in volumeSensors cost above 100$. The proposed fiber sensor is capable of recognizing different blends of ethanol-gasoline or methanol-gasoline20

Dr. Avi Zadok, Bar-Ilan Univ. Feb. 2014Apps (3): Recognition of flexible fuel blendsMethanol concentration in gasoline:

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The sensor readout for each blend is differentDr. Avi Zadok, Bar-Ilan Univ. Feb. 201421Potential ApplicationsIdentifying flexible fuel blendsDetection of fuel fraud and dilution, at the gas station and inside the carMonitoring the production of bio-diesel (for example, using methanol and micro-waves)Monitoring the efficiency of internal combustion process, reduce pollutionQuality control of water, beverages and foodMobile point-of-care diagnostics (NUFAR program, to begin March 2014). 22Dr. Avi Zadok, Bar-Ilan Univ. Feb. 2014Conclusion

23Dr. Avi Zadok, Bar-Ilan Univ. Feb. 2014