Inkjet Printing of Interdigitated Capacitive Chemical Sensors with Reduced Size by the Introduction of a Dielectric Interlayer

Abstract

A new fabrication strategy is proposed to reduce the size of sensors based on inkjet-printed interdigitated electrodes (IDE). The process is compatible with fabrication at low temperature and can be applied to flexible organic foils. The new fabrication concept consists of the deposition of a thin dielectric layer of parylene-C onto the first electrodes comb prior to the printing of the second one. In this way, the combs are not longer on the same plane, preventing undesired short-circuits and solving the typical problems of definition and yield associated to inkjet printing of IDE devices with small pitch. The proposed strategy results especially relevant for capacitive-based devices, where short-circuits render the device non-functional. Moreover, it permits enhancing their capacitance per surface area. The validation of the exposed process for sensors application has been carried out by functionalizing the IDE structure with a humidity sensing layer, and characterizing the resulting sensor against changes in relative humidity (R.H.). (C) 2012 Elsevier Ltd .... Selection and/or peer-review under responsibility of the Symposium Cracoviense Sp. z.o.o.