Nonlinear Nanomechanical Mass Spectrometry at the Single-Nanoparticle Level

TL;DR

This paper introduces a novel measurement approach for nonlinear nanomechanical mass spectrometry that enables rapid, sensitive detection of individual nanoparticles, overcoming limitations of traditional linear methods.

Contribution

The authors develop a measurement architecture that operates in the nonlinear regime, allowing for effective mass sensing of nanoparticles beyond the linear dynamic range.

Findings

Successfully characterized individual gold nanoparticles

Obtained a mass spectrum of 20 nm gold nanoparticles

Demonstrated operation in the nonlinear regime for mass sensing

Abstract

Nanoelectromechanical Systems (NEMS) have emerged as a promising technology for performing the mass spectrometry of large biomolecules and nanoparticles. As nanoscale objects land on NEMS sensor one by one, they induce resolvable shifts in the resonance frequency of the sensor proportional to their weight. The operational regime of NEMS sensors is often limited by the onset-of-nonlinearity, beyond which the highly sensitive schemes based on frequency tracking by phase-locked loops cannot be readily used. Here, we develop a measurement architecture to operate at the nonlinear regime and measure frequency shifts induced by analytes in a rapid and sensitive manner. We used this architecture to individually characterize the mass of gold nanoparticles and verified the results by performing independent measurements of the same nanoparticles based on linear mass sensing. Once the feasibility of the technique is established, we have obtained the mass spectrum of a 20 nm gold nanoparticle sample by individually recording about five hundred single particle events using two modes working sequentially in the nonlinear regime. The technique obtained here can be used for thin nanomechanical structures which possess a limited dynamic range.