EBG-based Sensor for Dielectric Characterization in Liquids

A novel, low-cost and compact microwave sensor based on Electromagnetic Bandgap Structure (EBG) has been proposed to detect and sense the change in the reflection coefficient of a compact Koch fractal patch antenna for different dielectric constant liquids at 2.45 GHz ISM Band. The proposed design of a sensor is composed of a 2 × 2 array of square unit cells as an EBG plane, and a Koch modified fractal antenna designed on a specialized polymer-based Rogers 5880 substrate. A trench is etched out from the substrate in between the 2 × 2 unit cells of EBG plane to act as a microfluidic channel for deposition of the liquids. A variation in the reflection phase of an EBG plane is observed when these etched out microfluidic channels are filled with liquids of different permittivities using a patch antenna placed on it at a height of $0.082\lambda_{0}$ . To verify this concept, three liquids of different dielectric properties (butan-1-ol, ethanol, and methanol) are filled in the microfluidic channels of EBG plane. A significant change in the reflection coefficient of a patch antenna is observed with good quality factor and sensitivity. Our demonstrated EBG-based sensor remarkably decrease the cost and the size of a sensing platform without compromising sensitivity and provides a route to realize highly efficient and affordable sensor for dielectric characterization in liquids and detection of contaminants in daily edible items.