Ultrasensitive mass sensing using mode localization in coupled microcantilevers

Abstract

We use Anderson or vibration localization in coupled microcantilevers as an extremely sensitive method to detect the added mass of a target analyte. We focus on the resonance frequencies and eigenstates of two nearly identical coupled gold-foil microcantilevers. Theoretical and experimental results indicate that the relative changes in the eigenstates due to the added mass can be orders of magnitude greater than the relative changes in resonance frequencies. Moreover this sensing paradigm possesses intrinsic common mode rejection characteristics thus providing an alternate way to achieve ultrasensitive mass detection under ambient conditions.

A force sensor based on three weakly coupled resonators with ultrahigh sensitivity

“…10 The conventional approach employs a single degree-of-freedom (DoF) resonator; when an external force is exerted on the resonator, the stiffness changes while the mass remains the same, leading to a frequency shift [9]. The challenge to improve the performance of the force sensor, aiming to sense smaller forces motivates research in alternative sensing paradigms.…”

“…One promising approach, which couples two identical resonators with a spring much weaker than that of the resonators, is to form a 2DoF system [10]. This approach utilizes a mode localization effect which was first described in solid-state physics by Anderson [11].…”

“…When a small perturbation is applied on one of the resonators, the mode shapes of the system change. It was demon-20 strated that by measuring the eigenstates shift caused by mode localization, orders of magnitude improvement in sensitivity of mass change was observed [10]. Various groups demonstrated that orders of magnitude enhancement in sensitivity of stiffness change [12,13,14,15] and force [16] could be achieved using this approach.…”

Characterization of forced localization of disordered weakly coupled micromechanical resonators

“…Researchers have developed strongly coupled resonators using frequency splitting as the output metric to improve the sensitivity by more than 20% 13 . Using weakly coupled resonators (WCRs) and taking the eigenstate or amplitude ratio as the output metric can enhance the sensitivity by more than 2 orders of magnitude 14 . A variety of sensors based on WCRs with different degrees of sensitivity enhancement have been implemented, such as mass sensors [14][15][16][17] , electrometers 18,19 , stiffness sensors 20,21 , accelerometers 22 , and tilt sensors 23 .…”

Tunable mechanical coupling between driven microelectromechanical resonators

“…Depending on the type of comb-drive actuator, this induced strain can be either tensile or compressive. The former allows the disentanglement of strain and charge carrier density effects in mechanical resonators, whereas the latter is particularly relevant to gain control over buckling modes in mechanical resonators [34,35].Coupled micro-and nanomechanical resonators are known to show sensitive sympathetic oscillation dynamics that show better performance in potential applications than a single resonator [36][37][38][39][40]. One major challenge for this type of resonators is an in-situ control over the coupling [41].…”