Sensitivity Study of a Coplanar Waveguide Antenna-Based Sensor for Hydration Monitoring

This paper presents a study on a coplanar waveguide (CPW) antenna-based sensor operating at frequency of 2.4 GHz. Designed with a compact size of 30 mm × 30 mm, the antenna-based sensor utilizes filtered paper as its substrate material. The performance analysis of the CPW antenna-based sensor focuses on evaluating its sensitivity in detecting various types of sweat for hydration monitoring. The investigation encompasses a range of hydration levels, including hydrated, intermediate, dehydrated and severely dehydrated sweat. Results indicate that the CPW antenna-based sensor demonstrated high sensitivity to sweat, as evidenced by significant shifts in resonant frequency with increasing sweat volume. The maximum simulated frequency shift observed is 1.79 GHz when the CPW antenna-based sensor is fully immersed in sweat, compared to a 0.43 GHz shift at 10% immersion. The CPW antenna-based sensor effectively distinguishes between hydration states, with hydrated sweat exhibiting a substantial frequency shift of 74.21 % while dehydrated sweat showed a 45.42 % frequency shift.