Traverse shear mode piezoelectric chemical sensor

A process for sensing a chemical change in molecular conformation or mass of a biomolecule attached to the surface of a transverse shear piezoelectric sensing device driven by a network analyser, said change being attributable to a binding interaction between said biomolecule attached to the surface and a biological entity in a surrounding liquid medium upon exposure of the surface to the surrounding liquid medium, said process comprising the steps of:

• i) exciting said sensing device at a series of predetermined frequencies prior to and during exposure to the surrounding liquid medium;
• ii) collecting data from the sensing device to determine values for parameters:
• series resonance frequency shift (fS), motional resistance (Rm), motional inductance (Lm), motional capacitance (Cm), electrostatic capacitance (Co), and boundary layer slip parameter (α);
• iii) determining a relative change in said parameters in step ii) upon exposure of the surface to the surrounding liquid medium;
• and
• iv) correlating the relative change in said parameters determined in step iii) with a calibrated set of data for said parameters to determine a change in molecular conformation or mass of the biomolecule attached to the surface attributable to a binding interaction upon exposure to the surrounding liquid medium;
• wherein a change in boundary layer slip parameter (α) and an essentially zero change in the series resonance frequency shift (fS) confirms a change in molecular conformation and essentially zero change in mass of the biomolecule attached to the surface.