Nontraditional methods of mass sensing using isolated and coupled microcantilevers

Vijay Kumar, Purdue University

Abstract

Over the past two decades, mass sensors based on resonant microcantilevers have garnered significant interest from the research community, due to their small size, low power consumption, high sensitivity, and low cost, when bulk fabricated. Modern resonant mass sensors typically utilize chemomechanically-induced frequency shifts in linear resonators for analyte detection. While this has proven utility, recent results indicate that sensors which utilize non-conventional sensing architectures have the potential to exhibit improved sensor metrics and operate more effectively at smaller scales. Accordingly, this work explores the possibility of using two distinct, nontraditional approaches for mass sensing purposes: (i) utilizing dynamic transitions across saddle-node bifurcations to develop an amplitude-based sensor, and (ii) using an electromagnetically-coupled array of resonators to develop a single input - single output, multiple analyte sensor. The first part of this work focuses on the development of an amplitude-based sensing approach, which utilizes dynamic transitions across saddle-node bifurcations that exist in the frequency response of a directly-excited system for mass detection. Specifically, this part details the modeling, analysis, and experimental validation of the bifurcation-based sensing technique using a piezoelectrically-actuated microcantilever. The analytical and experimental results presented herein provide an improved understanding on the nonlinear dynamic behaviors of such resonators and validate the feasibility of the proposed nonlinear sensing approach. The latter part of the work details the development of a single input - single output mass sensor based on globally-coupled arrays of microcantilevers. These devices utilize the induced emf in an array of frequency-mistuned microcantilever structures vibrating in a permanent magnetic field to detect multiple analytes. This work details the modeling, analysis, design, fabrication and preliminary experimental investigations of these globally-coupled arrays. The results indicate that the proposed technique is not only a viable method for sensing, but can greatly simplify implementation and integration tasks.

Degree

Ph.D.

Advisors

Rhoads, Purdue University.

Subject Area

Mechanics|Mechanical engineering

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