Real-Time Signal Processing Method for Obtaining Charge Distribution on Aerosols Produced by Medical Inhalers

The paper discusses a novel noninvasive method of measurement of a charge level on a population of particles using phase doppler anemometry (PDA). The PDA system is used to track the motion of charged particles in the presence of an electric field. By solving the equation of particle motion in a viscous medium combined with the simultaneous measurement of its size and velocity, the magnitude as well as the polarity of the particle charge can be obtained. A signal processing scheme based on Phase Locked Loop has been proposed to obtain the particle charge in real time. A MATLAB/SIMULINK model has been implemented and tested in the range particle velocities of 10~320 mm/s and corresponding particle charge levels from several electrons to the Gaussian Limit.