Polymer-based chemical sensors

(in collaboration with the laboratory of Polymer-based Sensors and Systems, INN, Demokritos)

The quantitative detection and monitoring of VOCs and moisture by chemical sensors is based on changes of a physicochemical property of the polymeric sensing layer due to absorption of the target vapour analyte. The operation of the low cost, low energy consumption capacitive- type sensors, is based on changes in the dielectric properties of the polymer layer due to sorption of the vapour analyte. For a particular geometrical design of a capacitive sensor, sorption properties determine not only the sensitivity of the sensor to a particular VOC but also its selectivity for the target VOC in real complex environments. 

Schematic side view of an InterDigitative capacitive (IDC) sensor.

Our collaboration with the laboratory of Polymer-based Sensors and Systems, includes development and evaluation of (i) optical methodologies for fast screening the sorption properties of polymeric materials for gas sensor applications1-2 (ii) simulation methodologies for the prediction of chemocapacitors performance.3 The increase in sensitivity/selectivity of chemocapacitors is sought through modification and miniaturisation of the geometrical configuration of the sensor’s electrodes4-5 or, through using polymer composites as sensing layers6. Finally sensor arrays are developed at the laboratory of Polymer based Chemical sensors for specific applications, such as the monitoring the must fermentation process7, or the detection and continuous monitoring of VOCs and/or moisture in complex vapor environments (e.g. industrial installations using solvents8-9). 

 More details can be found under the heading “Polymer based sensors and systems” in the “Nanoelectronics, Photonics and Microsystems” program of INN.

Chemocapacitors modeling flow chart. Inputs are (a) the dielectric constants of pure polymer and pure analyte (b) the volume fraction of sorbed analyte, estimated by optical swelling measurements and (c) the Interdigitated electrodes layout. Output is the sensors capacitance for any concentration of analyte sorbed under investigation

Testing of the modelling approach (full points) to experimental capacitance data (open points) of chemocapacitors coated with three different polymers upon exposure to various vapour concentrations of tetrahydrofuran (taken from ref [3])

A self-calibrated Wireless Sensing System (WSS), based on a sensor array of chemocapacitors, after evaluation under laboratory conditions, was then tested in the industrial installation of a printing flexing packaging industry, for real -time monitoring of the concentration of specific Volatile Organic Compounds present in the said workspace (taken from ref [9])

Selected references 

  1. D. Goustouridis, K. Manoli, S. Chatzandroulis, M. Sanopoulou and I. Raptis  “Characterization of polymer layers for silicon micromachined bilayer chemical sensors using white light interferometry”” Sens. Act. B: Chemical 111-112 (SUPPL.), (2005) 549-554
  2. K. Manoli, D. Goustouridis, S. Chatzandroulis, I. Raptis, E. S.Valamontes, M. Sanopoulou  “Vapor sorption in thin supported polymer films studied by white light interferometry”, Polymer, 47 (2006) 6117-6122.     
  3. P. Oikonomou, A. Botsialas, K. Manoli, D. Goustouridis, E. Valamontes, M. Sanopoulou, I. Raptis, G. P. Patsis “Chemocapacitor performance modeling by means of polymer swelling optical measurements” Sens. Act. B: Chemical,  171-172 (2012)  409-415
  4.  Z. Wang, A. Syed, S. Bhattacharya, X. Chen, U. Buttner, G. Iordache, K. Salama, Th. Ganetsos, E. Valamontes, A. Georgas, I. Raptis, P. Oikonomou, A. Botsialas, , M. Sanopoulou “Ultra miniaturized InterDigitated Electrodes platform for sensing applications”  Microelectron Eng  225 (2020) 111253
  5. P. Oikonomou, A. Botsialas, N. Papanikolaou, I. Kazas, K. Ntetsikas, G. Polymeropoulos, N. Hadjichristidis, M. Sanopoulou, I. Raptis “Gas sensitivity amplification of interdigitated chemocapacitors through etching” IEEE Sensors Journal, 20 (2020) 463-470
  6. K, Manoli, P. Oikonomou, E. Valamontes, I. Raptis, M. Sanopoulou “Polymer-BaTiO3 composites: dielectric constant and vapor sensing properties in chemocapacitor applications”  J. Appl. Polym. Sci., 125 (2012) , 2577-2584
  7.  P. Oikonomou, I. Raptis,  M. Sanopoulou “Monitoring and Evaluation of Alcoholic Fermentation Processes Using a Chemocapacitor Sensor Array”  Sensors 14 (2014)  16258-16273
  8. Oikonomou, P., Botsialas, A., Olziersky, A., Hadjigeorgiou E.P., Katsikas S., Dimas D., Sotiropoulos G., Raptis, I., Sanopoulou, M. « A wireless sensing system for monitoring the workplace environment of an industrial installation» Sensors and Actuators, B: Chemical 224, (2016) pp. 266-274
  9. Oikonomou, P., Botsialas, A., Olziersky, A., Hadjigeorgiou E.P., Katsikas S., Dimas D., Sotiropoulos G., Raptis, I., Sanopoulou, M. « A self-calibrated Wireless Sensing System for monitoring the ambient industrial environment. From lab to real-time application» Sensors and Actuators, B: Chemical 237 (2016) pp. 509-520

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