Surface Adsorbate Fluctuations and Noise in Nanoelectromechanical Systems

Physisorption on solid surfaces is important in both fundamental studies and technology. Adsorbates can also be critical for the performance of miniature electromechanical resonators and sensors. Advances in resonant nanoelectromechanical systems (NEMS), particularly mass sensitivity attaining the single-molecule level, make it possible to probe surface physics in a new regime, where a small number of adatoms cause a detectable frequency shift in a high quality factor (Q) NEMS resonator, and adsorbate fluctuations result in resonance frequency noise. Here we report measurements and analysis of the kinetics and fluctuations of physisorbed xenon (Xe) atoms on a high-Q NEMS resonator vibrating at 190.5 MHz. The measured adsorption spectrum and frequency noise, combined with analytic modeling of surface diffusion and adsorption−desorption processes, suggest that diffusion dominates the observed excess noise. This study also reveals new power laws of frequency noise induced by diffusion, which could be important in other low-dimensional nanoscale systems

Ultra-High Frequency Nanoelectromechanical Systems with Low-Noise Technologies for Single-Molecule Mass Sensing

Advancing today's very rudimentary nanodevices toward functional nanosystems with considerable complexity and advanced performance imposes enormous challenges. This thesis presents the research on ultra-high frequency (UHF) nanoelectromechanical systems (NEMS) in combination with low-noise technologies that enable single-molecule mass sensing and offer promises for NEMS-based mass spectrometry (MS) with single-Dalton sensitivity. The generic protocol for NEMS resonant mass sensing is based on real-time locking and tracking of the resonance frequency as it is shifted by the mass-loading effect. This has been implemented in two modes: (i) creating an active self-sustaining oscillator based on the NEMS resonator, and (ii) a higher-precision external oscillator phase-locking to and tracking the NEMS resonance. The first UHF low-noise self-sustaining NEMS oscillator has been demonstrated by using a 428MHz vibrating NEMS resonator as the frequency reference. This stable UHF NEMS oscillator exhibits ~0.3ppm frequency stability and ~50zg (1zg = 10-21 g) mass resolution with its excellent wideband-operation (~0.2MHz) capability. Given its promising phase noise performance, the active NEMS oscillator technology also offers important potentials for realizing NEMS-based radio-frequency (RF) local oscillators, voltage-controlled oscillators (VCOs), and synchronized oscillators and arrays that could lead to nanomechanical signal processing and communication. The demonstrated NEMS oscillator operates at much higher frequency than conventional crystal oscillators and their overtones do, which opens new possibilities for the ultimate miniaturization of advanced crystal oscillators. Low-noise phase-locked loop (PLL) techniques have been developed and engineered to integrate with the resonance detection circuitry for the passive UHF NEMS resonators. Implementations of the NEMS-PLL mode with generations of low-loss UHF NEMS resonators demonstrate improving performance, namely, reduced noise and enhanced dynamic range. Very compelling frequency stability of ~0.02ppm and unprecedented mass sensitivity approaching 1zg has been achieved with a typical 500MHz device in the narrow-band NEMS-PLL operation. Retaining high quality factors (Q's) while scaling up frequency has become crucial for UHF NEMS resonators. Extensive measurements, together with theoretical modeling, have been performed to investigate various energy loss mechanisms and their effects on UHF devices. This leads to important insights and guidelines for device Q-engineering. The first VHF/UHF silicon nanowire (NW) resonators have been demonstrated based on single-crystal Si NWs made by bottom-up chemical synthesis nanofabrication. Pristine Si NWs have well-faceted surfaces and exhibit high Q's (Q ≈ 13100 at 80MHz and Q ≈ 5750 at 215MHz). Given their ultra-small active mass and very high mass responsivity, these Si NWs also offer excellent mass sensitivity in the ~10?50zg range. These UHF NEMS and electronic control technologies have demonstrated promising mass sensitivity for kilo-Dalton-range single-biomolecule mass sensing. The achieved performance roadmap, and that extended by next generations of devices, clearly indicates realistic and viable paths toward the single-Dalton mass sensitivity. With further elaborate engineering, prototype NEMS-MS is optimistically within reach.</p

Roadmap on semiconductor-cell biointerfaces.

This roadmap outlines the role semiconductor-based materials play in understanding the complex biophysical dynamics at multiple length scales, as well as the design and implementation of next-generation electronic, optoelectronic, and mechanical devices for biointerfaces. The roadmap emphasizes the advantages of semiconductor building blocks in interfacing, monitoring, and manipulating the activity of biological components, and discusses the possibility of using active semiconductor-cell interfaces for discovering new signaling processes in the biological world

Nouveau concept de spectrométre de masse à base de réseaux de nanostructures résonantes

The aim of the project is to bring a proof of concept of a simplified mass spectrometer architecture using an ultra dense network of NEMS in association with elements of CMOS circuit as sensors in order to amplify the signal in situ and adress them individually. Since several years, Roukes' team at Caltech has demonstrated a mass spectrometry with a NEMS. In parallel, the CEA/LETI-MINATEC has developped a fabrication approach called VLSI of NEMS and an electromecanical simulation method of these elements The first objective of this thesis is to study the noise phenomenon currently limiting our mass resolution in order to reach 10 Da instead of current 1000 Da on ranges going from 10 Da to 1MDa. In a second step, the concept of NEMS-based mass spectrometry is validated by comparison a nanometric cluster spectra with those from a conventional time-of-flight mass spectrometer. Then, a frequency addressing technique is applied on an NEMS array to allow for quasi simultaneous tracking of 20 different resonators. Finally, the NEMS array is inserted in the nanocluster bench to measure 20 spectra in parallel and validate a first proof of concept.L'enjeu du travail est d'apporter une preuve de concept d'une architecture simplifiée de spectromètre en utilisant comme détecteur un réseau ultra-dense de NEMS associés à des éléments de circuit CMOS afin d'amplifier le signal in situ et de les adresser individuellement. Depuis plusieurs années, l'équipe du professeur Roukes à CALTECH a présenté une démonstration de spectrométrie de masse avec un NEMS. En parallèle, le CEA/LETI-MINATEC a développé une approche de fabrication dite VLSI de NEMS et de simulation électromécanique de ces éléments. Le premier but de la thèse est l'étude des phénomènes de bruit limitant la résolution en masse afin d'atteindre 10 Da au lieu des 1000 Da actuels sur des rangs de masses large allant de 10Da à 1MDa. Dans un second temps, La concept de spectrométrie de masse à base de NEMS est validé en comparant des spectres obtenus sur des nano-agrégats de quelques nanomètres de diamètres avec ceux fournis par un spectromètre de masse temps-de-vol conventionnel. Puis, un système d'adressage fréquentiel de réseau de NEMS est mis en place pour permettre la mesure quasi simultanée de 20 résonateurs. Enfin, le réseau de NEMS est inséré dans le banc de nano-aggrégats pour mesurer 20 spectres de masses en parallèle et valider une première preuve de concept

Advances in Micro- and Nanomechanics

This book focuses on recent advances in both theoretical and experimental studies of material behaviour at the micro- and nano-scales. Special attention is given to experimental studies of nanofilms, nanoparticles and nanocomposites as well as tooth defects. Various experimental techniques were used. Magneto- and thermoelastic coupling were considered, as were nonlocal models of thin structures

20公分翼展以下之拍翼式微飛行器的縮小化與減重研究(3/3)

[[abstract]]本3 年期個人型計畫目標，在於開發翼展20 公分以下之拍翼式微飛行器(flapping MAV)的縮小化與減重技術。根據拍翼飛行生物之尺寸律(scaling law)，20 公分翼展MAV 對應之最大機重應只有20 多克，10 公分翼展MAV 對應之最大機重更只有3 克，在必須囊括機身、拍翼、與馬達機電動力來源 等裝置下，減重工藝殊為不易。眾皆耳聞的’微機電’(MEMS)技術，是縮小化之良方，然放眼目前已成功飛行的拍翼MAV，MEMS 技術頂多用於機翼空氣 動力效能提升等局部性之改善，對於立體全機之縮小化與減重，尚未提供全面性的因應。再者，拍翼飛行牽涉之三維非定常空氣動力學與飛行力學研究，尚在方興未艾階段，如何進行拍翼機之飛行穩定控制，對於未來自主性MAV 之發展至為重要，而現有機載電子通訊裝置過重，如何大幅減重到尺寸律範圍之內，仍保有控制的功能，便不只是單純MEMS 技術可已解決，甚而要將技術觸角 延伸到系統晶片。是以本計畫擬定以下三個年度之工作進度目標: 第一年: 翼展20 公分以下之拍翼式微飛行器多元化機構與外形設計；第二年: 以微機電技術增益翼展20 公分以下之拍翼式微飛行器及其研製；第三年: 以微機電與系統晶片技術增益翼展10 公分級之拍翼式微飛行器改良。預期將穩定滯空的拍翼MAV，縮小翼展到10-20 公分之間，並規劃完成自主式拍翼MAV 的機載控制系統單晶片之架構。[[sponsorship]]行政院國家科學委員會[[booktype]]電子

Modeling the Molecular Communication Nanonetworks

Nanotechnology is a cutting edge investigation area that has come out with new and unlimited applications. The recent explosion of research in this field, combined with important discoveries in molecular biology have created a new interest in bio-nanorobotic communication. This thesis provides a general theoretical understanding of nanonetworks and their multiple possibilities. It describes some basic concepts of architectures that compose nanotechnology topologies, as well as possible designs for the tiny nanonetwork components, the nanomachines. The thesis also reviews some promising methods proposed for communicating and coordinating in these nanonetworks. Molecular communication applied to nanonetworks presents indeed extremely appealing features in terms of energy consumption, reliability and robustness. Nevertheless, it remains to understand the impact of the extremely slow propagation of molecules and the highly variable environments. As a totally unexplored research area, it is important to establish thorough theoretical framework so that the applications and possible solutions can be validated. It is clear that many issues still need to be addressed in order to understand the limiting performance of information communications among nano-scale devices and design optimal and quasi-optimal encoding/decoding strategies. Such issues are believed to be of key relevance for allowing nanotechnologies display their full potential

Microfluidic Tools for Advanced Biomolecular Characterisation

Proteins – the key building blocks of life – are responsible for the majority of the processes behind biological function. To understand what role proteins play in health and disease, how they operate and interact, it is vital to have tools for biomolecular detection, quantification and fundamental physicochemical characterisation. In this thesis, I have focused on the development of new microfluidic approaches enabling quantitative analysis of biomolecules. First, I describe a microfluidic spray device, developed for a controlled deposition of analyte on surfaces. Due to the small micron-scale droplet size, the evaporation happens in a few milliseconds, thus, leaving only the solvent-free solutes. This method has been vital for depositing biomolecules on a scanning-probe microscopy-imaging substrate, enabling quantitative measurements of heterogeneous protein mixtures. Afterwards, I present the spray combination with gravimetric sensors, such as micro-cantilevers, for a label-free protein detection. I show that this technique can be used for a protein-solution concentration measurement in a quantitative manner. Currently, one of the main issues of diagnostic platforms is the analysis of heterogeneous mixtures. A number of protein-separation techniques have been developed; however, most of the characterisation requires an offline analysis which can introduce artefacts and reequilibration. In the second part of this dissertation, I bridge the gap between liquid chromatography, microfluidic characterisation and mechanical-sensor detection. Specifically, I demonstrate the serial combination between liquid chromatography and analyte deposition by a microfluidic spray nozzle. By depositing analytes onto a quartz-crystal microbalance, I perform a specific label-free analysis of protein mixtures. Furthermore, I present a fluidic interface, facilitating a combination of separation at fast liquid flow with microfluidic size and electrophoretic-mobility measurements. This method allows for a simultaneous measurement of molecule size and charge and acts as an additional chromatographic detector. I demonstrate that this method works for both label-free and labelled biomolecule characterisation and suggests ways to perform scalable mass-spectrometry analysis on a chip