DESIGN, SIMULATION OF CAPACITIVE TYPE SENSOR TO DETECT MICROSCOPIC PARTICLES IN LIQUID CHANNEL ORIENTED FOR BIOMEDICAL APPLICATIONS

Abstract

This paper presents design and simulation of capacitive sensor structure to detect particles in liquid channel. The
sensor structure consists of 3 circular electrodes mounted at fixed positions outside the plastic pipe, including one
electrode signal generator (excitation) and the other two electrodes placed symmetrically at on both sides of the
excitation electrode, these two electrodes are the collecting electrode. Plastic pipes are pumped with a liquid solution of
pure water with a dielectric constant of 81. The proposed capacitive sensor can detect magnetic particles attached with
living cells of small sizes ranging from 80µm to 140µm. When the magnetic particles move in the liquid channel and move
into the capacitance sensor, the magnetic particles will change the dielectric in the capacitor sensor, thereby changing the
value of the capacitance differential of the capacitor and we determine the appearance of magnetic particles in the liquid
channel. Sensor performance was investigated by finite element method (FEM) using Ansoft Maxwell simulation
software. The simulation results show the difference in differential capacitance corresponding to the appearance of
magnetic particles. Based on this simulation result, the size of the electrodes was found to have the sensor configuration
with the necessary sensitivity. The optimal size of the sensor with the parameters m = 100µm, l = 1mm, r = 200µm,
n = 50µm. Sensors can be applied in biomedical to detect magnetic particles attached to T-CD4+ living cells to detect viral
hepatitis, HIV/AIDS.