Architecture for the efficient manufacturing by printing of heated, planar, resistive transducers on polymeric foil for gas sensing

This paper presents a new coplanar architecture to implement the electrodes and the heating element of printed gas sensors. The design includes two electrodes and three contacts. One of the electrodes works as heating element and, simultaneously, drains the sensing current. The electrical modelling of the transducers and its electronic implementation are reported. As this new approach is related to the electrical topology of the system, a reduction in the number of conductive elements will be obtained for any geometry, deposition method, and gas sensing layer. Compared with other coplanar topologies, this approach simplifies the transducers processing to a single printing step, avoiding the use of an inter dielectric layer between heater and electrodes, and reducing the amount of electrically conductive ink necessary to pattern heater and electrodes of the transducers. This cost-effective architecture and process was applied to the fabrication of heated transducers for metal-oxide gas sensors. The two electrodes were made by inkjet printing of gold on polyimide foil. For the validation of the concept, a Pt loaded WO3 sensing layer was grown on top of these transducers printed with the proposed topology. When tested against H-2, diluted in air, their response was as good as the one obtained employing the classical topology. This simple architecture has strong potential for the realization of fully printed resistive gas sensors and can be implemented as well in clean room processed transducers. (C) 2017 Elsevier B.V. All rights reserved.