B.I. Zapadinskii, R.G. Kryshtal, A.V. Medved, A.V. Roshchin
Some results on investigation of SAW sensitive elements for chemical sensors based on MEMS structure with molecularly imprinted polymer (MIP) coating layer are described. SAW of Rayleigh type were used in sensitive elements intended for working in gas environment, while SAW with shear-horizontal polarization (waves of Gulyaev-Bleushtein type) were used in elements intended for liquid environment. MIP layer, serving as nano-dimensional molecular traps for a certain molecules, served for increase of sensor sensitivity in respect to these molecules. MIP synthesized with morpholyne molecules as a template was used as an example in SAW sensitive elements under investigation.
Experimental results on investigation of features of sorption processes on the surface covered by MIP layer in sensitive elements on Rayleigh SAW at 120 MHZ, fabricated on the YZ LiNbO3 substrate are given. Abnormal slowing of desorption process for morpholyne in comparison with all other analytes was discovered. Possibilities of use of the obtained results for creation of selective gas chemical sensors on SAW are discussed.
Sensitive elements for liquids were constructed on the base of layered structures with 36O YX LiTaO3 as a substrate. SH-SAW were excited and propagate in these structures. Principal possibilities of recognition of liquid analytes including these with small admixture of morpholyne by means of the single SH-SAW sensor have been experimentally demonstrated, no sensor arrays as in any other traditional liquid recognition systems like electronic tongue being used. Physical explanation of working basis of such a recognition device is given. Application possibilities are discussed.