Odorant detection via Solidly Mounted Resonator biosensor

In this paper, a biosensors for vapour phase detection of odorant molecules based on Solidly Mounted Resonators (SMRs) is presented. The SMRs were coated with a wild-type bovine odorant-binding protein (wtbOBP), used as sensing layer, and consisted of a piezoelectric aluminium nitride (AlN) film sandwiched between two metal electrodes. An acoustic Bragg reflector was fabricated on the silicon substrate to ensure the acoustic insulation. The wtbOBPs were deposited on the top electrode of resonators by means of the droplet method. The SMR biosensor was tested in nitrogen upon exposure to R-(-)-1octen-3-ol (octenol) vapours in the range of concentrations between 7 and 27 ppm. An uncoated device was used to compensate the responses due to variations in environmental parameters. The differential response curve showed a linear behaviour in the tested range of concentrations and the obtained sensitivity was of 600 Hz/ppm.