The Effect of Humidity on Microwave Characteristics of Screen Printed Paper‐Based Electronics

Abstract

This paper addresses one of the key issues in using paper electronics at microwave frequencies. As paper is hygroscopic, the varying moisture content can lead to differing dielectric and even conductive properties of paper electronics and must be taken into consideration in any device design. In this work, coplanar waveguides (CPWs) have been screen printed using silver ink on matt paper. Increasing the relative humidity between 40 and 90% is shown to increase the losses, decrease the propagation velocity and decrease the characteristic impedance of CPWs. The effect of water on both silver flake ink and the matt paper used in this work are considered, and it is shown that the change in permittivity of the substrate as a result of absorbed water within paper is the most dominant factor on the microwave characteristics. The reported findings should be considered in paper‐based applications at microwave frequencies, as the changes in transmission‐line parameters can lead to drastic variations in device and system operation.

Printed Solar Cells and Energy Storage Devices on Paper Substrates

“…[161] Dimensional changes are normally reversible at low ambient humidity, but, above 65% humidity, they start to irreversibly affect the paper structure. [162] These morphological changes can impact any device operation [45] and adoption of a coating layer is beneficial for preserving contacts morphology, as demonstrated for printed silver linear electrodes on papers of different qualities subjected to cycles of exposure to humidity and thermal stress. [38] Improved dimensional stability was found for nanopaper containing up to 90 % of kaolin or precipitated calcium carbonate (PCC) fillers.…”