Effect of mechanical properties variation of polysilicon on microcantilever mass sensor sensitivity

Ensuring a high sensitivity for piezoelectric microcantilever sensors constitutes a crucial research subject particularly for the applications such as detection of biochemical entities; virus particles or human biomarkers. However, this sensitivity may change due to the environmental conditions such as temperature, or/and the uncertainty in the material properties, which cause the mechanical properties of the cantilever material changes. The objective of this study is to explore the effect of Young modulus variations of cantilever's structural layer on the sensitivity of the mass sensor. Also, this effect has been investigated for different sensor lengths and resonance modes. As theoretical model, Euler-Bernoulli beam theory has been employed and solved by Galerkian expansion procedure. The results show that error in sensors sensitivity due to variation of Young modulus is almost 3% in this study, and this remains constant regardless of beam length or the resonance mode of the cantilever sensor. Also, the sensitivity of microsensor decreases with increasing the loaded mass. The microsensor sensitivity operating at the second resonant mode has been improved almost five times comparing to the first mode sensitivity regardless of cantilever length.