Microwave Grooved SRR Sensor for Detecting Low Concentration Ethanol-Blended Petrol

Abstract

The rise in global energy demand due to economic development and an increase in population, have posed major concerns regarding energy security and environmental impact. Ethanol-blended petrol is an emerging alternative fuel that is considered cost-effective and environmentally friendly. However, the detection of low concentrations of ethanol in petrol is a significant challenge, especially as most nations mandate the blending of petrol with 5%-25% ethanol. This paper proposes a microwave sensor operating at 2.4GHz ISM band frequency to detect low concentrations of ethanol in petrol. The change in the magnitude of the reflection coefficient is adopted as the main sensing parameter. A single-frequency sensor composed of a square-shaped monopole loop antenna embedded with an SRR is proposed, which avoids the need for a wideband interrogation signal. The proposed design utilizes a filter paper wetted with the ethanol-petrol solution, placed along the split edge of the SRR, thus the use of complex and costly fluidic channels and space-consuming sample holders is avoided, bringing down the cost and complexity. The device dimensions are small, 4.2cm x 4.5cm. The sensitivity achieved in terms of amplitude change of the reflection coefficient is 2.83dB/5 % change of ethanol concentration in petrol, at a fixed frequency. In terms of the received power at 2.4GHz, the sensitivity is 2dBm/5 % change of ethanol concentration. Overall, this proposed sensor offers a simple, cost-effective, and efficient solution for detecting low concentrations of ethanol in petrol, which can aid in the adoption of ethanol-blended petrol as a viable alternative fuel.