Sensing and characterization of single nanoparticles by vacuum-free nanoelectromechanical systems with an integrated polymeric lens

Abstract

Machines in the nanoscale dimension had the opportunity to become a top-notch choice to detect and characterize nanoparticles thanks to the rapid progress in micro-nano fabrication. Sensors that can detect and identify nanoparticles al-lowed the analysis of the physics on the scale of nanometers. In the last decade, nano-electromechanical systems are evolved with the integration of electronics to the mechanical nano dimensional structures to sense the mass of particles. Their small form factor, high sensitivity to mass changes, and compatibility with the microchip fabrication process placed NEMS in a position to be an excellent can-didate for sensing applications. In contrast, high sensitivity that is coming from their minuscule size of active area for mass detection comes with the cost of hav-ing minimal efficiency in capturing the nanoparticles in concern. Moreover, the need for vacuum equipment for the transportation of the nanoparticles confined NEMS-MS applications to the laboratories. Here, we resolved these problems by integrating a polymeric lens on top of the NEMS sensors in order to transport and direct the incoming nanoparticles, utilizing the electric field only, towards the minuscule active detection area; with exploiting change of the electric field in between nanoparticle source and NEMS, due to the accumulating surface charges over the polymeric lens. Therefore, we executed mass sensing measurements and obtained the mass spectrum of the 40 nm diameter gold nanoparticles and 100 nm diameter polystyrene nanoparticles without differential vacuum equipment, with a rapid analysis time and high capture efficiency.