Sensing Capabilities of Single Nanowires Studied with Correlative In Situ Light and Electron Microscopy

Abstract

Modern devices based on modular designs require versatile and universal sensor components which provide an efficient, sensitive, and compact measurement unit. To improve the space capacity of devices, miniaturized building elements are needed, which implies a turning away from conventional microcantilevers toward nanoscale cantilevers. Nanowires can be seen as high-quality resonators and offer the opportunity to create sensing devices on small scales. To use such a one-dimensional nanostructure as a resonant cantilever, a precise characterization based on the fundamental properties is needed. We present a correlative electron and light microscopy approach to characterize the pressure and environment sensing capabilities of single nanowires by analyzing their resonance behavior in situ. The high vacuum in electron microscopes enables the characterization of the intrinsic vibrational properties and the maximum quality factor. To analyze the damping effect caused by the interaction of the gas molecules with the excited nanowire, the in situ resonance measurements have been performed under non-high-vacuum conditions. For this purpose, single nanowires are mounted in a specifically designed compact gas chamber underneath the light microscope, which enables direct observation of the resonance behavior and evaluation of the quality factor with dependence of the applied gas atmosphere (He, N 2 , Ar, Air) and pressure level. By using the resonance vibration, we demonstrate the pressure sensing capability of a single nanowire and examine the molar mass of the surrounding atmosphere. Together this shows that even single nanowires can be utilized as versatile nanoscale gas sensors.

Unraveling the Highly Plastic Behavior of ALD‐Aluminum Oxide Encapsulations by Small‐Scale Tensile Testing

“…[27] Such metallic NWs are known for their high aspect ratio and their high quality. [28,29] The NWs emerge from a substrate piece and are subsequently coated via ALD. We use the established process for ALD-Al 2 O 3 coatings [30] based on the two precursors water and TMA.…”

Optimizing Atomic Layer Deposition Processes with Nanowire‐Assisted TEM Analysis

“…In this study, we use metal nanowires (Cu and Au) made by a physical vapor deposition process at elevated temperatures. [ 24 ] While these wires are convenient as they can be grown directly on a TEM grid and have high quality and stability, [ 25 ] in principle all sorts of nanowires can be used as templates for the process such as semiconductors [ 26 ] or metal oxides. [ 27 ] To showcase the potential of using commercial wires, we tested the deposition on solution‐grown silver nanowires (see Figure S1, Supporting Information).…”

Chemical Sensors using Single‐Molecule Electrical Measurements

“…[9] Developing chemical sensors with higher selectivity, higher sensitivity, and faster response time has always been the core goal in single-molecule electronics. [10][11][12] In the past few decades, the laws of interaction between the electrical conductivity measured by the sensing center and the target material have led to creating of various types of sensing technologies, such as nanopores, [13,14] nanowires, [15][16][17][18] carbon nanopores, [19][20][21] microfluidics, [22] and single-molecule fluorescence microscopy. [23,24] Single-molecule electrical characterization technology makes it possible to directly characterize the electrical properties of a single-molecule at several nanometers.…”