ACOUSTIC PLATE MODE SENSOR FOR IMMUNOCHEMICAL REACTIONS

A practical immunosensor, based on a 150-MHz acoustic plate mode (APM) device on ZX-LiNbO3 has been built and is employed to monitor directl y, in real time, antigen-antibody reactions via mass loading of the cr ystal surface. The results show frequency shifts similar to 1 kHz abov e the noise level upon antigen adsorption. The mass density detection limit of our present sensor is similar to 200 pg/mm(2), corresponding to 8.10(8) molecules/mm(2) utilizing a typical Ige of 150 000 Da. Anti gen binding capacities of aminosilane films are measured independently by a modified ELISA test and are related to the APM sensor response.