A COMPREHENSIVE MODELING OF PIEZORESISTIVE MICROCANTILEVER SENSORS USED IN PIEZOACTIVE MATERIALS CHARACTERIZATION

摘要

Micro-Cantilever Sensors (MCS) have caught a widespread attention during past couple of years for offering label free biodetection. Amongst many current MCS-based measurement platforms, piezoresistive MCS offer a great advantage over other types of MCS especially when compared with optical measurements where sample preparation and laser alignment and adjustment are serious limitations. In order to address the uncertainties and nonlinearities inherent in nanoscale, a comprehensive modeling of the system is required. In almost all of the studies targeting piezoresistive MCS, the system is modeled as a simple lumped-parameters system which does not describe all phenomena and dynamics of the system. In the first part of this study, a comprehensive distributed-parameters modeling is proposed for the piezoresistive MCS. A new method of excitation is developed and modeled through cantilever tip instead of the commonly used techniques such as base excitation or excitation through piezo-layers deposited over cantilever surface. In the second part of this study, a comprehensive distributed-parameters modeling is proposed for the piezoresistive MCS-based force microscopy in contact with a piezoelectric sample. The output voltage of the piezoresistive layer is determined and utilized as a function of cantilever deflection through a piezoresistive modeling framework. Extensive numerical simulations are performed to demonstrate the effectiveness of the modeling framework presented here.