Self-reading femtogram microbalance for highly sensitive airborne nanoparticle detection

Abstract

In this paper, a self-reading miniaturized cantilever design for highly sensitive airborne nanoparticle (NP) detection is presented. The cantilever, which is operated in the fundamental in-plane resonance mode, is used as a microbalance with femtogram resolution. For maximum sensitivity and read-out signal amplitude, the geometric parameters of the sensor design were optimized by finite-element modelling (FEM). Piezo-resistive struts at both sides of the cantilever are employed for a Wheatstone half-bridge. This allows the electrical read-out of the phase information of a resonant cantilever of minimum mass. For electrostatic NP collection, the cantilever has a negative-biased electrode located at its free end. Moreover, μ-channels for guiding a particle-laden air flow and a counter-electrode around the cantilever tip are integrated. The presented airborne NP sensor is expected to demonstrate significant improvements in the field of handheld, MEMS-based NP monitoring devices.