RESEARCH AND OPTIMAL DESIGN OF A CAPACITIVE TYPE COPLANAR SENSOR TO DETECT LIVING CELLS IN LIQUID MICROCHANNEL

Abstract

This paper presents the research, optimal design of the size of the coplanar capacitive micro sensor structure to detect living
cells applied in biomedicine. The sensing structure consists of two small, thin flat electrodes mounted in fixed positions on a flat
glass base below the liquid microchannel, where one serves as the emitter electrode (excitation electrode) and the other
electrode is placed parallel on the same plane as the collector electrode. The liquid channel has dimensions of 30µm x 40µm,
which is pumped with a liquid solution of pure water with a dielectric constant of 81. The proposed sensor can detect living cells
as small as 15 µm in diameter. When the live cell moves in the conduction channel and passes through the capacitive coplanar
sensor placed below the conduction channel, the cell will change the dielectric in the sensor, thereby changing the capacitance
value of the sensor , this helps us determine the presence of that living cell. Sensor performance was investigated by finite
element method (FEM) using Ansoft Maxwell simulation software. The simulation results show the capacitance change in the
presence of live cells. Based on this simulation result, the size of the electrodes was found to have a sensor configuration with the
required sensitivity. The optimal size of the sensor was found with the parameters a = 60µm, b = 40µm, d = 10µm,
h = 0.15µm, electrode coating thickness t = 10µm. The sensor can be used in biomedical applications to detect living cells for
disease diagnosis, such as detecting A549 living cells to detect lung cancer and some other similar viral infections.