A fully inkjet-printed wireless chipless sensor is presented that uses split ring resonators printed with three different inks to independently detect CO2 and temperature through polarization responses. A polymer/carbon nanotube composite ink detects both CO2 and temperature, while an additional polymer coating is shown to reduce CO2 sensitivity without affecting temperature detection. Simulations and experiments validate the repeatability of the sensor's design and functionality.

1. A Fully Inkjet-Printed Wireless and Chipless Sensor for CO2 and
Temperature Detection
Abstract:
A study on a low-cost wireless fully inkjet-printed chipless sensor on a
flexible laminate with three different inks is presented. It is based on two
split ring resonator 90° oriented between each other to allow for
independent responses on two polarizations. A deposit of a polymer/single
walled carbon nanotube composite ink is used to allow for the detection of
CO2 as well as temperature. In this paper, it is shown that the inkjet
printing of a polymer-based coating on top of the sensing/reactive deposit
can significantly reduce the sensitivity to CO2, whereas the temperature
sensitivity stays at same. Simulations and experimental results verify the
repeatability of this topology.