Open AccessFemtogram aerosol nanoparticle mass sensing utilising vertical silicon nanowire resonators
Author(s) -
Wasisto Hutomo Suryo,
Merzsch Stephan,
Stranz Andrej,
Waag Andreas,
Uhde Erik,
Salthammer Tunga,
Peiner Erwin
Publication year - 2013
Publication title -
micro and nano letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.25
H-Index - 31
ISSN - 1750-0443
DOI - 10.1049/mnl.2013.0208
Subject(s) - nanoparticle , resonator , aerosol , nanowire , silicon , nanotechnology , materials science , silicon nanowires , optoelectronics , chemistry , organic chemistry
Vertically aligned silicon nanowire (SiNW)‐based resonators were fabricated and utilised to detect aerosol nanoparticles (NPs) by measuring their resonant frequency shifts caused by the additional mass of trapped NPs. Inductively coupled plasma cryogenic dry etching and multiple thermal oxidations are used in the fabrication of silicon nanowire (SiNW) arrays. The SiNWs were coated with gold for contacting to the homebuilt electrostatic NP sampler to collect the flowing NPs. In order to have a dynamic resonance operation in the frequency measurement system, a piezoelectric shear actuator was mounted onto the SiNWs. Examined in a TiO 2 aerosol sampling with a total concentration of ∼8500 NP/cm 3 , the fabricated sensor exhibited its feasibility as a nanobalance to measure aerosol NP mass at the femtogram level with a mass sensitivity of 7.1 Hz/fg and a mass resolution of 31.6 fg. The NP sampling efficiency of the developed miniaturised NP sampler was found to be three times higher than that of the commercial nanometer aerosol sampler (NAS, TSI 3089). An ultrasonic removal method was used to detach the adhered NPs and further extend the operating life of the sensor.