Low-cost wearable cantilever-based nanoparticle sensor microsystem for personal health and safety monitoring

A low-cost pocket-sized airborne nanoparticle (NP) detector based on a silicon microelectromechanical cantilever is described oscillating at its fundamental in-plane resonance frequency. For direct reading of NP concentrations, the monitoring system consists of signal-conditioning electronics for NP sampling as well as tracking of frequency shift by the attached NP mass. Weight and cost of this first fully integrated personal gravimetric airborne NP monitor (Cantor-2) are comparable to low-cost optical fine-particle sensors but beyond this it can detect ultra-fine particles (UFPs) of less than 100 nm in diameter. Real-time measurements with engineered carbon NPs as well as carbon black NPs exhibited a zero-offset linear correlation to reference measurements using a standard fast mobility particle sizer (FMPS). A limit of detection (LOD) of better than 10 μg/m³ was found within a response time of 6 min, i.e., a typical short-term NP exposure duration.