Graphene-Oxide-Coated Flexible Fabric Antenna Sensor for Contact-Free H₂O Sensing

Abstract

This article presents a flexible antenna sensor on denim jeans fabric for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{O}$ </tex-math></inline-formula> sensing. A small defected ground structure is developed on the copper ground plane of the antenna. Graphene oxide (GO) is coated on the defected ground for sensor applications. The flexible antenna sensor with GO coated on a defected ground plane resonates at 5.52 GHz. The resonance frequency of the proposed antenna changes linearly with the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{O}$ </tex-math></inline-formula> content. The frequency sensitivity of the denim fabric antenna sensor is ≈203 MHz/10% relative humidity (RH). The denim fabric antenna sensor has a measured phase sensitivity of 40° per 10% RH. The flexible antenna sensor gives a linearity of 98.28%. The designed antenna sensor can distinguish between fresh and dried grapes by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{O}$ </tex-math></inline-formula> detection.