Kristiansen Kai, McGuiggan Patricia, Carver Greg, Meinhart Carl, Israelachvili Jacob
Departments of Chemical Engineering and Mechanical Engineering, and Materials Research Laboratory, University of California-Santa Barbara, CA 93106, USA.
Langmuir. 2008 Feb 19;24(4):1541-9. doi: 10.1021/la702380h. Epub 2007 Dec 8.
A new device has been designed, and a prototype built and tested, that can simultaneously measure the displacements and/or the components of a force in three orthogonal directions. The "3D sensor" consists of four or eight strain gauges attached to the four arms of a single cross-shaped force-measuring cantilever spring. Finite element modeling (FEM) was performed to optimize the design configuration to give desired sensitivity of force, displacement, stiffness, and resonant frequency in each direction (x, y, and z) which were tested on a "mesoscale" device and found to agree with the predicted values to within 4-10%. The device can be fitted into a surface forces apparatus (SFA), and a future smaller "microscale" microfabricated version can be fitted into an atomic force microscope (AFM) for simultaneous measurements of the normal and lateral (friction) forces between a tip (or colloidal bead probe) and a surface, and the topography of the surface. Results of the FEM analysis are presented, and approximate equations derived using linear elasticity theory are given for the sensitivity in each direction. Initial calibrations and measurements of thin film rheology (lubrication forces) using the "mesoscale" prototype show the device to function as expected.
一种新设备已设计出来，其原型已制造并测试，该设备能够同时测量三个正交方向上的位移和/或力的分量。这种“3D传感器”由四个或八个应变片组成，这些应变片附着在单个十字形测力悬臂弹簧的四个臂上。进行了有限元建模（FEM）以优化设计配置，从而在每个方向（x、y和z）上获得所需的力、位移、刚度和谐振频率灵敏度，这些在一个“中尺度”设备上进行了测试，发现与预测值的偏差在4%至10%以内。该设备可安装到表面力装置（SFA）中，未来更小的“微尺度”微加工版本可安装到原子力显微镜（AFM）中，用于同时测量尖端（或胶体珠探针）与表面之间的法向力和横向（摩擦力）以及表面形貌。给出了有限元分析的结果，并给出了使用线性弹性理论推导的每个方向灵敏度的近似方程。使用“中尺度”原型对薄膜流变学（润滑力）进行的初步校准和测量表明该设备按预期运行。
