Intrinsic and Extrinsic Losses in Nanoelectromechanical Systems

纳米机电系统的内在和外在损耗

• 批准号: 1506619
• 负责人: Narayana Aluru
• 金额: $ 36.28万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506619&HistoricalAwards=false
• 关键词: Intrinsic; Extrinsic; Losses; Nanoelectromechanical; Systems

Title: Intrinsic and Extrinsic Losses in Nanoelectromechanical SystemsProject Goals:To develop a fundamental understanding of energy losses in nanostructures and to exploit this knowledge for enhanced performance of nanostructuresNontechnical Abstract:Nanoelectromechanical systems (NEMS) have attracted significant interest as they promise high frequencies and quality factors (Q). However, many recent experimental studies have observed that the mechanical quality factor, Q, defined as the ratio of the energy stored to the energy lost per unit period, of NEMS is much lower than those from theoretical predictions. This discrepancy can be attributed to the novel physics that arises at the nanoscale and is not accounted for in the classical theory. The attainable frequencies in NEMS are comparable to the phonon frequencies and this can introduce new sources of intrinsic dissipation, such as Akhiezer damping, which can significantly reduce the quality factors. In addition, as the surface to volume ratio is higher at nanoscale, surfaces act as an additional source of dissipation reducing the Q. To realize the full potential of NEMS, it is important to develop a comprehensive physical understanding of all dissipation mechanisms at nanoscale. Through this knowledge, high Q nanostructures can be engineered. Since classical theories do not adequately describe dissipation at nanoscale, the focus of this project is to develop atomistic and multiscale approaches to understand dissipation in nanostructures.This project will provide interdisciplinary research, education and training of graduate and undergraduate students and the research results will be widely disseminated for broader impact.Technical Abstract:Two types of mechanical losses, namely intrinsic and extrinsic, will be considered and understood. Intrinsic losses or energy dissipation mechanisms are those that are inherent to the nanostructure. Popular sources of intrinsic dissipation are Akhiezer damping, thermo-elastic damping, surfaces, defects, etc. Most nanostructures operate in a fluid medium, so in addition to intrinsic losses, extrinsic losses, defined as the dissipation caused by the fluid, also needs to be taken into account. The key objectives of this project are to (i) Develop atomistic and multiscale computational approaches to understand intrinsic losses in a variety of one-dimensional and two-dimensional nanostructures. Comprehensive theories to model Akhiezer, thermo-elastic, defects, surfaces and other sources of intrinsic dissipation will be developed. (ii) Develop atomistic and multiscale computational approaches to understand extrinsic losses. To determine extrinsic losses, coupled fluidic and structural analysis is necessary. To compute fluidic forces acting on the nanostructure, a comprehensive multiscale approach will be developed. The multiscale approach for fluidic analysis will be coupled with a multiscale approach for nanostructural analysis to determine extrinsic losses. (iii) Establish validation of the computational approaches by comparing computed quality factors with experimental data. In addition, various applications of NEMS such as high frequency resonators, energy harvesting and mass sensing will be pursued.

标题：纳米机电系统系统目标中的内在和外在损失：为纳米结构中的能量损失发展基本了解，并利用这些知识来增强纳米结构的性能，以增强纳米技术摘要：纳米机械力学系统（NEMS），因为他们在高频率和质量上都吸引了巨大的兴趣。然而，许多最近的实验研究观察到，机械质量因子Q定义为存储的能量与单位周期损失的能量的比率，NEM的NEM量远低于理论预测中的能量。这种差异可以归因于在纳米级出现的新颖物理学，并且在经典理论中没有考虑到。 NEM中可达到的频率可与声子频率相媲美，这可以引入新的内在耗散来源，例如Akhiezer阻尼，这可以显着降低质量因素。此外，由于纳米级的表面与体积比较高，因此表面是减少Q的耗散源的附加来源，以实现NEM的全部潜力，重要的是要对纳米级的所有耗散机制进行全面的物理理解，这一点很重要。通过这些知识，可以设计高Q纳米结构。由于古典理论不能充分描述纳米级的耗散，因此该项目的重点是开发原子和多尺度的方法来了解纳米结构中的耗散。该项目将提供跨学科的研究，毕业生和培训的研究和培训。理解。内在损失或耗能机制是纳米结构固有的损失机制。固有耗散的流行来源是Akhiezer抑制作用，热弹性阻尼，表面，缺陷等。大多数纳米结构都在流体介质中运行，因此除了固有的损失，外部损失（定义为由流体引起的耗散）外，还需要考虑。 该项目的关键目标是（i）开发原子和多尺度计算方法，以了解各种一维和二维纳米结构中的内在损失。将开发建模Akhiezer，热弹性，缺陷，表面和其他内在耗散来源的全面理论。 （ii）开发原子和多尺度计算方法以了解外部损失。为了确定外部损失，需要进行耦合的流体和结构分析。为了计算作用于纳米结构的流体力，将开发一种全面的多尺度方法。用于流体分析的多尺度方法将与用于确定外部损失的纳米结构分析的多尺度方法结合使用。 （iii）通过将计算质量因素与实验数据进行比较来确定计算方法的验证。此外，将追求NEM的各种应用，例如高频共振器，能量收集和质量感应。