Real-time single airborne nanoparticle detection with nanomechanical resonant filter-fiber

Abstract

Nanomechanical resonators have an unprecedented mass sensitivity sufficient to detect single molecules, viruses or nanoparticles. The challenge with nanomechanical mass sensors is the direction of nano-sized samples onto the resonator. In this work we present an efficient inertial sampling technique and gravimetric detection of airborne nanoparticles with a nanomechanical resonant filter-fiber. By increasing the nanoparticle momentum the dominant collection mechanism changes from diffusion to more efficient inertial impaction. In doing so we reach a single filter-fiber collection efficiency of 65 ± 31% for 28 nm silica nanoparticles. Finally, we show the detection of single 100 nm silver nanoparticles. The presented method is suitable for environmental or security applications where low-cost and portable monitors are demanded. It also constitutes a unique technique for the fundamental study of single filter-fiber behavior. We present the direct measurement of diffusive nanoparticle collection on a single filter-fiber qualitatively confirming Langmuir's model from 1942.

Evidence of Surface Loss as Ubiquitous Limiting Damping Mechanism in SiN Micro- and Nanomechanical Resonators

“…Since the discovery of the exceptionally high quality factors (Q) of nanomechanical silicon nitride (SiN) resonators [1,2], SiN strings and membranes have become the centerpiece of many experiments in the fields of cavity optomechanics [3][4][5][6][7][8][9][10][11][12][13] and sensor technology [14][15][16][17][18][19]. For example in cavity optomechanics a high Q at high frequencies is required in order to advance towards the quantum regime of the mechanical resonators, and in resonant sensors a high Q enables a better resolution.…”

“…The study of these intrinsic losses in low-stress membranes with varying lengths L and thicknesses h reveals an inverse linear dependence of the intrinsic loss with h for thin resonators independent of L. This finding was confirmed by comparing the intrinsic dissipation of arbitrary (membranes, strings, and cantilevers) SiN resonators extracted from literature, suggesting surface loss as ubiquitous damping mechanism in thin SiN resonators with Q surf = β · h and β = 6 × 10 10 ± 4 × 10 10 m −1 . Based on the intrinsic loss the maximal achievable Qs and Q · f products for SiN membranes and strings are outlined.Since the discovery of the exceptionally high quality factors (Q) of nanomechanical silicon nitride (SiN) resonators [1, 2], SiN strings and membranes have become the centerpiece of many experiments in the fields of cavity optomechanics [3][4][5][6][7][8][9][10][11][12][13] and sensor technology [14][15][16][17][18][19]. For example in cavity optomechanics a high Q at high frequencies is required in order to advance towards the quantum regime of the mechanical resonators, and in resonant sensors a high Q enables a better resolution.…”

Mass Spectrometry Using Nanomechanical Systems: Beyond the Point-Mass Approximation

“…We focus on the one-dimensional resonator formula, Eq. (4), because (i) these structures are widely used [1][2][3][4][5][6][7][8], and (ii) the properties of this formula are identical to Eq. (6) for twodimensional structures.…”

“…Nanomechanical resonators can be used as fast and sensitive mass balances due to their small mass, high vibrational frequencies and low intrinsic energy dissipation [1][2][3][4][5][6][7][8]. The strong dependence of mass responsivity on device size has driven the development of a new type of mass spectrometer based on inertial mass sensing using nanoelectromechanical systems (NEMS) [9,10].…”

The Nano-Particle Mass Classifier (Nano-PMC): Development, Characterization, and Application for Determining the Mass, Apparent Density, and Shape of Particles with Masses Down to the Zeptogram Range

“…A number of new methods that can directly determine particle mass, including time-of-flight mass spectrometers and nanoscale cantilevers (Schmid et al 2012), have been introduced in recent years. Another promising instrument, introduced by Ehara et al (1996), is the aerosol particle mass analyzer (APM), which is now commercially available (Kanomax Model APM-3600).…”