Mass Sensitivity Evaluation and Device Design of a LOVE Wave Device for Bond Rupture Biosensors Using the Finite Element Method

The LOVE wave devices based on a number of composite structures have been designed and simulated in this paper for use as a bond-rupture biosensor. Bond-rupture biosensors use acoustic energy to probe the bond strength between the sensor substrate and the analyte. The sensitivity and displacement of LOVE wave sensors can be implemented due to energy concentration inside a guiding layer on the surface of a piezoelectric crystal. The choice of substrate and guiding layer material is the critical basic elements in the proper design of a LOVE wave biosensor applications. Finite element method (FEM) is a suitable numerical method to analyze and design the LOVE wave device. A 3-D FEM model has been created and defined to simulate the displacement response of the acoustic wave system. The LOVE wave can be clearly observed, and the total surface displacement can reach a value of 10^-11m, which can easily induce the bond rupture between antibody and antigen. A 2-D model has been established to simulate the mass sensitivity with different composite structures of 128° YX LiNbO₃, 36° YX LiTaO₃, ST-quartz-PMMA and 128° YX LiNbO₃, and 36° YX LiTaO₃ and ST-quartz-SiO₂. These results indicate that the 128° YX LiNbO₃PMMA is the most suitable for bond rupture biosensors due to its high sensitivity and maximum displacement on the surface of piezoelectric crystal.