Mechanical stress relaxation in adhesively clamped carbon nanotube resonators

Abstract

We report a detailed experimental investigation of the adhesive clamping instability in CNT nanoresonators fabricated on silicon wafers with palladium electrodes and suspended CNT channels. The nanotube is clamped down onto the palladium electrodes adhesively by van der Waals forces and operates in the string regime. We observe a decrease in the nanotube tension when the device is operated in large amplitude regime. This mechanical stress relaxation, or decrease in internal stress of the nanotube, was observed as a frequency downshift resulting from weak clamping behavior between the nanotube and the underlying palladium surface. Frequency downshifts from 97.5 MHz to 39 MHz with 60 % stress relaxation and from 72.7 MHz to 60.5 MHz (17 % relaxation) were observed for two devices. Q-factors show no change due to decrease in internal stress. Our temperature measurements in the range of 298-420 K suggest that Q-factors might arise from the interplay between adhesive clamping associated dissipation mechanisms and spectral broadening due to thermal fluctuations.

Clamping and Q-Factor Improvement in a Carbon Nanotube Resonator

“…The observed Q-factors in nanotubes and other nanoresonators are still largely unexplained and deviate from theoretical expectations [4]. While various reported experimental and theoretical work on CNTs assumed perfect clamping conditions, recently reported experimental investigations suggest clamping instability between CNT and the underlying metal contact [5,6]. Effect of different clamping geometries on carbon nanotube resonators at room temperature and low pressure to our knowledge has not been reported yet.…”

“…The trench depth for gate electrode was etched through reactive ion etching (RIE) and palladium electrodes were evaporated through lift-off process [7]. The nanotubes were grown on a separate designated silicon chips and then mechanically dry-transferred [8] onto FET electrodes as reported in [5]. The nanotube is clamped down mechanically onto the palladium electrodes due to van-der-Waals forces resulting in a bottom clamped configuration.…”

Solidworks Simulation of Mechanical Properties of Recycled Plastics/Nanocomposite Faces Sandwich Panels

“…Virgin Properties Effect of recycling Effect of filler on recycled properties Sources HDPE behavior in tensile 16.6% degradation a 63.3% increase b (Jiun, et al, 2016) (Reddy, 2006) HPEC compression strength (MPa) 24.82 c 20.7 33.865 (Corneliussen, 2002 (Kumar, et al, 2018) (Zhao and Shi, 2011)…”

Clamping effects on mechanical stability and energy dissipation in nanoresonators based on carbon nanotubes

“…This allows for a decrease in the internal tension of the nanotube and is observed as a resonance frequency downshift. A detailed experimental investigation of reduction in the internal tension in bottom clamped nanotube devices has been reported in our previous work 20 .…”

“…Most of the reported theoretical and experimental work on nanoresonators including carbon nanotubes have assumed perfect clamping conditions. However, recent reported results have experimentally proven the finite and weak adhesion forces leading to clamping instability in CNT based nanoresonators making a case against the assumption of perfect clamping conditions 19,20 . Very few experimental observations of dissipation due to clamping 21,22 have been reported, which limits the general understanding of clamping effects on nanoresonators, and motivates the following research.…”