Microfluidic Sensor for Dielectric Spectroscopy Measurement of Microliter Biological Fluids over 1-60 GHz

Abstract A wideband microfluidic sensor based on a microfluidic channel and a millimeter wave coplanar waveguide sensor is proposed. The sensor operates in a frequency band ranging from 1GHz to 60GHz and is used to measure the dielectric spectrum of microliter volume liquids. When the microwave signal incident on the interface of the liquid sample, transmission and reflection will occur, and the transmission and reflection coefficients are related to the dielectric constant of the liquid sample, and the dielectric constant of the sample to be measured can be deduced from the measured scattering parameters. The dielectric spectrum results measured at 150mmol/L NaCl were compared with the commercial Keysight results to verify the accuracy of the sensor. Finally, complex biological liquid samples tumor cell suspension MCF-7 and WBC were measured. The difference between NaCl solution and the working frequency band reflected the difference between different cell suspensions. The error range of the five consecutive measurements was much smaller than the difference between tumor cells. These results provide support for distinguishing different tumor cell suspensions.