Mode-localized sensing in micro- and nano-mechanical resonator arrays

Micromachined resonant sensors have been researched for several decades for a variety of applications with potential benefits in terms of improved sensitivity and scalability relative to other transduction principles. Conventional implementations usually involve detection elements monitoring resonant frequency and/or dissipation shift in a single degree-of-freedom or several independent degrees-of-freedom. This paper discusses a complementary approach to resonant sensing in which the eigenstates in coupled array structures can be employed as a read-out mechanism offering the potential for both increased sensitivity and excellent common mode rejection. The technique, dubbed “mode-localized sensing”, is based on the spatial localization of vibration in an array of nearly identical weakly coupled resonators wherein the eigenstates are seen to be sensitive signatures of symmetry-breaking perturbations in structural parameters. The sensing methodology has been applied to a range of applications including gravimetric sensing, electrometry, inertial sensors and force sensors where in high accuracy approaches to physical transduction are often of interest. The paper concludes with a discussion of the current challenges in the field and an outlook on future developments.