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

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 article proposes a microwave sensor operating at 2.4-GHz 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,
$4.2\times4.5$
cm. The sensitivity achieved in terms of amplitude change of the reflection coefficient is 2.83 dB/5% change of ethanol concentration in petrol, at a fixed frequency. In terms of the received power at 2.4 GHz, the sensitivity is 2 dBm/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.