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A Chemocapacitive sensor array for the detection of complex odors D. Goustouridis 1,2, P. Oikonomou 2, A. Botsialas 1,2, K. Manoli 2, M. Kitsara 2, I.

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Presentation on theme: "A Chemocapacitive sensor array for the detection of complex odors D. Goustouridis 1,2, P. Oikonomou 2, A. Botsialas 1,2, K. Manoli 2, M. Kitsara 2, I."— Presentation transcript:

1 A Chemocapacitive sensor array for the detection of complex odors D. Goustouridis 1,2, P. Oikonomou 2, A. Botsialas 1,2, K. Manoli 2, M. Kitsara 2, I. Raptis 2 1. Department of Electronics TEI Piraeus E-mail: dgousto@teipir.grdgousto@teipir.gr 2. Inst. Of Microelectronics NCSR Demokritos

2 2 nd SENS-ERA Workshop, 5-6 Dec. 2012 Overview Polymer based gas sensors Polymer based gas sensors Principles of operation Capacitive Polymer Based sensors Capacitive Polymer Based sensors Methodology for the selection of the Polymers Fabrication of the sensor array Capacitance measurement set-up Capacitance measurement set-up Capacitance measurements Read-out electronics Read-out electronics Capacitance measurements Applied Algorithms Applied Algorithms Applications Conclusions – Future Plans Conclusions – Future Plans

3 Chemical sensors Piezoelectic (surface acoustic waves SAW, bulk acoustic waves BAW, cantilever resonator) Optical (fluorescence, reflective, absorption) Thermal (pellistor) Electrical, Electrochemical ( chemoresistive, MOX, chemocapacitive) 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

4 Simple and low cost fabrication Simple and low cost fabrication Suitable for parallel production Suitable for parallel production Low power consumption Low power consumption Promising devices for sensing VOCs or humidity Promising devices for sensing VOCs or humidity Could be integrated with read-out electronics Could be integrated with read-out electronics + -+ Electrode Sensitive Layer Substrate λ h W G Top view Side view InterDigitateElectrode (IDE) Capacitive Sensor 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

5 Sorbed molecules + -+ Vapor phase Electrode Polymer sensitive layer Substrate λ h ΔC= f( ΔC ε + ΔC h ) Sorption of analyte Change in permittivity of polymer (ΔC ε ): i) ΔCε >0, ε A (analyte)>ε pol (polymer) ii) ΔCε <0, ε A (analyte)<ε pol (polymer) Swelling of polymer (ΔC h ): ΔC h >0 ΔC h ~0 if i) h>0.5 λ, ii) ε Α >> ε pol for any h Capacitance change (ΔC) IDE Chemocapacitor sensing principle 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

6 IDE Chemocapacitor sensing principle 2 nd SENS-ERA Workshop, 5-6 Dec. 2012 Electric Field Useful Capacitance Parasitic Capacitance Requirements: Substrate with low dielectric constant (Polymer or Quartz) Small electrode distance (ideally <1μm) ΔC ε : Capacitance change due to permittivity change ΔC h : Capacitance change due to swelling

7 IDE Chemocapacitor operating principle Α) Response of chamocapacitor in neutral enviroment, Β) Just before the first sorption Γ) After the sorption, transiet response Δ) Steady response in equilibrium 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

8 Development of an e-nose Choosing of the polymers for gas sorption Choosing of group of polymer (according to specific application) (Compatibility with the measuring gases, chemical affinity, technological issues, …) Control of sorption – desorption, repeatability, selectivity Transducer & Sensor Development Deposition techniques Implementation of Interdigitated Electrodes & characterization. Read-Out electronics Development of read-out electronics and data transmittion modules Development of Data processing algorithms Application of raw data processing algorithms for the identification of the gas composition. 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

9 Optical Characterization of the polymer swelling Measurement chamber Symbolemtry principle of operation The energy E at wavelength λ is (for the case of single layer film): n : Refractive index, L: thickness, λ: wavelength.με 0: πολυμερές 1:. 0 indicates the polymer layer & 1 the SiO 2 layer Fitting (L 0 ) of theoretical spectrum to the measurement one. White Light Reflectance Spectroscopy (WLRS) 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

10 Optical Characterization of the polymer swelling Polymer SiO 2 Si Nitrogen purging Analyte Atmosphere (swelling) Analyte atmosphere (swelling more) 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

11 Typical Results Polymer film: PHEMA Analyte: Humidity Concentrations: 1000-5000-10000-15000-20000 ppm Time (min) Thickness (nm) 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

12 Fabrication process of IDC Array Array of 8 chemopapacitors 2μm electrode – 2μm spacing (die size 7x7mm 2 ) Plan view of IDC structure 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

13 Measurement Set-up Time(min) Capacitance change (pF) 1.Gas delivering unit 2.Samples chamber (volume ~4mm 3 ) 3.Eight channel matrix switch board (Capacitance meter (HP 4278A) 4.The set-up is completely controlled by a LabView application 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

14 Measurement set-up 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

15 Response to concentrations of two analytes Δc double. ~(ΔC analyte1 + ΔC analyte2 ) The sensors sense the present or the absent of each analyte. 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

16 Aging through time 4 months later Good reproducibility and reversibility Time stability 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

17 Read out & Electronic Module Electronic circuit for up to 8 Chemocapacitance reading 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

18 Typical results of Electronic Module Mesurement of p-xylene(100ppm) with & without Humidity 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

19 PCA analysis Principal Component Analysis (PCA) Processing of the raw data 2 or 3 axes representation (the most important) 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

20 Application I. Wine discrimination Discrimination of white & red wine 1- Limnos white dry 2-Moschofilero-white Απόκριση του αισθητήρα PBMA-IDC στα τέσσερα κρασιά για δυο ροές Αποτέλεσμα PCA 3- Agiorgitiko- red - boutari 4- Naousa-red - boutari 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

21 Application II: Fragmentation monitoring Response of 2 IDC vs time Fragmentation vs time according to PCA analysis 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

22 Conclusions Methodology Development of Methodology for the characterization of polymer based chemocapacitors Polymeric Films Characterization of polymers films for odors sensing Chemocapacitors Array Development of implementation techniques of chemocapacitos Implementation & characterization of chemocapacitos Array Read out electronics Development of a hybrid system of chemocapacitors array with appropriate read-out electronics Λογισμικό ανίχνευσης αερίων Λογισμικό PCA Εφαρμογές Ζύμωση γλεύκους 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

23 Future plans Δίκτυο Development of submicron IDCs. Apply pattern recognition algorithms Implementation of a wireless network Measurements in real environment. 2 nd SENS-ERA Workshop, 5-6 Dec. 2012

24 Thank you for your attention E-mail: dgousto@teipir.gr 2 nd SENS-ERA Workshop, 5-6 Dec. 2012


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