Liquid heating can cause denaturation of sensing layer in SAW biosensors

The acoustic streaming phenomenon, i.e., fluid motion induced from high intensity sound waves, can be used effectively to remove nonspecifically bound proteins to allow reuse of SAW biosensors. While the streaming effect is clearly beneficial, this longitudinal irradiation into the fluid medium can also be accompanied by a corresponding temperature rise of the fluid near the SAW interface due to viscous dissipation, which can lead to denaturation of biosensing layer. Finite element solution of coupled wave propagation (piezoelectric domain) and Navier-Stokes equation (fluid domain) in conjunction with the energy balance equations were used to model the temperature rise of a liquid loading on top of a SAW device. Based on the temperature profiles, we identify the conditions that preserve the activity of the sensing layer as well as those leading to significant heating of the fluid domain. Our computational study highlights the fact that such increase in temperatures of the interfacial liquid layer can have significant implications for designing reusable and highly sensitive biosensors.