MRI-R2: Development of a Correlation Force Spectrometer

0959228 Ducker“该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。“对流体纳米级运动的更好理解对于我们理解复杂流体和生物分子的发展至关重要。PI建议开发一种仪器，测量分子和流体自然运动过程中的作用力，其能力超过目前所有仪器。该仪器将测量具有原子力显微镜（AFM）尖端或附着到自由端的胶体球的两个反平行杠杆的相关运动。尖端之间的流体将耦合两个杠杆，使得相关运动仅对介入流体敏感。与传统AFM相比，这种反平行排列将大大减少杠杆的贡献。相关运动的测量导致信噪比的大幅增加，因为相关性对各个杠杆上的电子、光学或机械干扰不敏感。此外，即使在单个悬臂上的热噪声也不是相关信号的一部分，因此仪器将具有比现有单悬臂AFM技术理论上可能的更低的噪声基底。该仪器将能够测量两个杠杆之间的单个分子的机械特性，以及复杂流体的粘弹性，其分辨率为纳米级，频率高达数百kHz。此外，机械概念的简单性为最终开发廉价和小型仪器提供了相对容易的途径。

0959228Ducker"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."An improved understanding of the nanometer-scale motion of fluids is central to the development of our understanding of complex fluids and biomolecules. The PI proposes to develop an instrument that measures the forces acting during the natural motion of molecules and fluids, with capabilities that exceed all current instruments. This instrument will measure the correlated motion of two antiparallel cantilevers that have atomic force microscope (AFM) tips or colloidal spheres attached to the free ends. The fluid between the tips will couple the two cantilevers such that the correlated motion is sensitive only to the intervening fluid. This antiparallel arrangement will greatly diminish the contribution of the cantilevers compared to conventional AFM. Measurement of the correlated motion results in a large increase in signal-to-noise ratio because the correlation is not sensitive to electronic, optical or mechanical disturbances on individual cantilevers. Moreover, even the thermal noise on the individual cantilever is not part of the correlation signal, so the instrument will have a lower noise floor than is theoretically possible for existing single cantilever AFM techniques. The instrument will be capable of measuring the mechanical properties of individual molecules tethered between the two cantilevers, as well as the viscoelastic properties of complex fluids with nanometer resolution at frequencies up to hundreds of kHz. Also, the simplicity of the mechanical concept provides a relatively easy path for ultimate development of an inexpensive and small instrument.