Investigation of the effect of adsorption induced surface stress on the resonant frequency of PZT membrane based biosensors

This article investigates the effect of protein adsorption induced surface stress on the resonant frequency of ultra-thin PZT membrane (~600 nm thick) based biosensors. The resonant frequencies of the mass sensitive micro-fabricated PZT biosensors should ideally decrease after external proteins are loaded; however, they are found to increase in this work. This abnormal phenomenon is studied by micro-Raman spectrum. The result shows that the resonant frequency change and the measured stress variation have the similar trend. This indicates that the abnormal phenomenon is attributed to the induced adsorption surface stress during the bio-immobilization process.