Study on sensitivities of Love-wave immunosensors based on SiO 2 /36°YX-LiTaO 3 and ZnO/36°YX-LiTaO 3 structures

Love-wave immunosensors based on SiO 2 /36°YX-LiTaO 3 or ZnO/36°YX-LiTaO 3 structures coated by special sensitive films have been fabricated and studied experimentally. A theoretical model using the partial wave theory of elastic waves propagating in three-layer structures covered by liquid loads is built up to calculate the sensitivities. To determine the elastic constants of the guiding layers, the phase velocities of the corresponding Love-wave devices are measured by a network analyzer, and the theoretical fitting of the experimental data are carried out. Then the relationships between the sensitivities of the Love-wave immunosensors and normalized thicknesses of the guiding layers are obtained, and there are optimized thicknesses of the guiding layers for getting maximum sensitivities. The experimental measurements and numerical calculations of the sensitivities of the Love-wave immunosensors show that both results are essentially consistent with each other.