Microfluidics-Based Tunable Printed Coplanar Waveguide Monopole Sensor
In this paper, we propose a coplanar waveguide monopole RF sensor design for fluidic sensing applications. The sensor design is based on coplanar monopole where two symmetric microfluidic channels are inserted between the grounds and the monopole radiator. The proposed sensor design is simulated in high frequency structure simulator (HFSS). The sensor is fabricated by depositing the conductive platinum (pt) on a low cost UV treated 100�m thick polyethylene terephthalate (PET) substrate through simple, fast and low cost sputtering technique. The resonant frequency of the RF sensor is tuned and varied according to the pumped fluidic inside the channels as their permittivity varies. For the empty channels, the resonant frequency was measured with vector network analyzer to be 1.98GHz and it varied to 1.9 GHz for distilled water filled channels. Hence, this frequency shift in the operating frequency of the sensor allows easy detection with good sensitivity. The proposed sensor can detect liquids such as water, ethanol and oil. The sensor can also identify small change in water contents such as tap water, distilled water and sea water. The reflection coefficient is under -30dB for ethanol, water, oil and empty case in the measured band. The proposed design can be used in various remote liquid detection applications in the industry and for bio-liquids sensing. The proposed design is low cost, disposable and need very small amount of liquid.
Index Terms- HFSS, microfluidic tunable, PET, Sputtering, Reflection Coefficient.