The paper investigates an electromechanical impedance (EMI) method and guided wave-based method propagation applied to the structural health monitoring of sensors network of thin plates. The genetic algorithm based optimized sensors network was used to maximize the area of sensitivity using the sensors. The planned calibration experiments performed on square thin aluminium plate with attached piezoelectric wafer active sensors (PWAS) at optimized sensors position. The study investigates the sensitivity of EMI and guided wave responses to the simulated damage positions of the plate. The initial study of the work is to identify the propagation of the waves in aluminum by looking at the baseline/pristine structures results. Later, it was observed that Lamb waves interact with the obstacle then the scattering and mode conversion takes place and lower amplitude waves get generated. Later, by using the ellipse-based approach the information about the damage position in the structures is gathered. The EMI method allows us to identify the effect of varying positions of damage in terms of damage metric of sensitive sensor positions. The basic idea of vibration based damage detection is a significant change in the stiffness, mass or energy dissipation properties. The EMI signature's sharp peaks identify the local structural modes of vibration due to the change in the health of the structure at the point of actuator attachment. New comparative approach was applied for the comparison of the EMI spectra from the considered sensor network. © APWSHM 2018. All rights reserved.