Comparison of Poly(methylmethacrylate) and Novolak waveguide coatings for an acoustic biosensor

In order to optimize the geometry of the acoustic waveguide biosensor, the performance of the device was assessed for two different guiding layers: a photeresist (Novolak) and a polymer Poly(methylmethacrylate) (PMMA) one. In itially, the effect of the thickness of each layer on the insertion loss of the device and frequency of the wave was monitored. The 1.5 and 1.7 mum No volak and PMMA, respectively, coated devices were used to monitor the bindi ng of Immunoglobulin G to the protein A activated device surface. Both devi ces were found to exhibit the same phase sensitivity to protein deposition. However, Novolak waveguides showed a higher stability in contact with wate r, making them more suitable for biosensing applications than PMMA waveguid es. Finally, the reproducibility of the Novolak-coated waveguide was studie d during the formation of the polymer layer, addition of buffer, and antibo dy binding. (C) 2001 American Institute of Physics.