A MEMS nano-extensometer with integrated de-amplification mechanism

Abstract

Experimental exploration of strained nanostructures, such as nanowires and bio-molecules, is essential for understanding their properties. However, the ability to apply and to quantify nanometer displacements is challenging. We present a novel MEMS nano-extensometer with integrated actuation and compliant de-amplification mechanism allowing the accurate characterization of stretched nanostructures. A feasibility study was followed by fabrication and characterization of the device. The deamplified displacement was registered via optical microscopy and was processed using an improved digital image correlation algorithm to achieve nanometer measurement accuracy. Using our technique, nanoscale displacement can be determined by means of simple imaging tools. This was demonstrated by stretching suspended single wall carbon nanotubes.

Suspended CNT-FET piezoresistive strain gauges: Chirality assignment and quantitative analysis

“…In contrast to earlier sensor configurations for suspended nanotubes without gates [3,15], here the bottom gate enables gauge factor tuning. As shown in Figure 3c, sensor readout at V g = 8 V instead of 4 V increased the gauge factor from 20 to 60 (θ = 27°).…”

“…Here, 40-nm-thick palladium was used. However, any material compatible with physical vapor deposition would be possible, including organic molecules, which could suffer in high temperatures and hydrogen atmospheres occurring in the approach of nanotube growth across pre-defined electrodes [3,5].…”

“…Moreover, the electrical contact materials are not exposed to high growth temperatures [3,12,15,17]. Direct transfer was used by others to fabricate nanotube resonators [22] and bent nanotube devices suitable for observation of valley-spin blockade [23].…”

“…Low power operation, large gauge factors, and small size of the piezoresistive sensing element [2] motivate the implementation of nanotube-based strain and displacement sensors [3][4][5].…”

Displacement sensing based on resonant frequency monitoring of electrostatically actuated curved micro beams

“…At each value of the voltage, the electrostatic solver yields the electrostatic pressure distributed on the surface of the beam; the mechanical solver analyzes elastic deformations of the beam loaded by the electrostatic pressure. The mechanical and the electrostatic problems were solved sequentially using a nonlinear iterative solver until convergence and the deformed configuration of the beam was obtained [32]. Figure 3a shows good agreement between the finite element and reduced order model results.…”