Characterization of silver–gallium nanowires for force and mass sensing applications

Abstract

We investigate the mechanical properties of cantilevered silver-gallium (Ag(2)Ga) nanowires using laser Doppler vibrometry. From measurements of the resonant frequencies and associated operating deflection shapes, we demonstrate that these Ag(2)Ga nanowires behave as ideal Euler-Bernoulli beams. Furthermore, radial asymmetries in these nanowires are detected through high resolution measurements of the vibration spectra. These crystalline nanowires possess many ideal characteristics for nanoscale force and mass sensing, including small spring constants (as low as 10(-4) N m(-1)), high frequency bandwidth with resonance frequencies in the 0.02-10 MHz range, small suspended mass (picograms), and relatively high Q-factors (approximately 2-50) under ambient conditions. We evaluate the utility of Ag(2)Ga nanowires for nanocantilever applications, including ultrasmall mass and high frequency bandwidth piconewton force detection.

The Mechanical Properties of Nanowires

“…Owing to its simplicity and efficiency in operation, the resonant vibration testing was widely used to determine the elastic modulus of NWs including Si,154, 166 Ge,167 Co,168 W,161, 169 SiC,170 GaN,99, 171 Ag 2 Ga,154 BN,172 ZnO,149, 165, 173, 174 WO 3 ,175 In 2 O 3 ,168 Sb 2 O 3 ,176 Al 2 O 3 ,164 amorphous SiO 2 ,177 metallic glasses 153. In particular, the use of SLDV not only significantly increases the detection resolution of a NW specimen's vibrational spectra, but also eliminates the issues relating to clamping and dimensional non‐uniformity 154, 161, 164.…”

“…In particular, the use of SLDV not only significantly increases the detection resolution of a NW specimen's vibrational spectra, but also eliminates the issues relating to clamping and dimensional non‐uniformity 154, 161, 164. Moreover, the resonance‐based testing can be performed without contact of a NW, thus not necessitating the consideration of temperature effects on force and displacement measurements.…”

A Thermoacoustic Model for High Aspect Ratio Nanostructures

“…Based on the results of Section 2, nanoresonators have been selected as the candidates for a 1D nanomechanical tool: a Ag2Ga nanowire (cylindrical shape with high density and bending modulus) [35,51] and a zinc oxide (ZnO) nanobelt (square crosssection) [26,27]. Table 1 shows the properties of the selected nanoresonators.…”

“…Although they used the same concept and definition for free molecular flow, crossover and continuum regime, they considered the Ag 2 Ga nanowire in the free molecular regime and suggested an equation for Q factor estimation as Q i = ω i ρA 4bP πR 0 T 2M m [8,35], where (i) represents different modes for the lateral vibration of the beam, ω i is the angular natural frequency of nanoresonator at different modes; ρ is the density of nanoresonator; A is the cross-sectional area of the nanoresonator; b is the effective area for damping per unit length; P is the pressure; R o is the universal gas constant; T is the temperature; and M m is the molecular weight. Unfortunately, the results of this equation are not consistent with their experimental Q factor findings using laser Doppler vibrometry resulting in a large error in estimated Q factors [8,35]. For the first mode, the experimental Q factors were 1.2, whereas the Q factor using the above-estimated equation was only 0.49, creating an almost 58% difference between the estimated and the experimental values.…”

Integration of Ag2Ga nanoneedles on batch fabricated micro-grippers for material property measurement.

“…These nano-needles form easily in liquid gallium at room temperature (melting point of gallium is 29.7646°C). [ 53,54] …”