Sensing nanonewton level forces by visually tracking structural deformations

When assembling MEMS devices or manipulating biological cells it is often beneficial to have information about the force that is being applied to these objects. This force information is difficult to measure at these scales. We demonstrate a method to reliably measure nanonewton scale forces applied to a micro scale cantilever beam using a computer vision approach. A template matching algorithm is used to estimate the beam deflection to sub-pixel resolution in order to determine the force applied to the beam. The template, in addition to containing information about the geometry of the beam, contains information about the elastic properties of the beam. Minimizing the error between this elastic template and the actual image by means of numerical optimization techniques, we are able to measure forces to within /spl plusmn/3 nN. In addition, we also discuss how this method can be generalized to measure forces in elastic configurations other than a simple cantilever beam using a micro-tweezer as an example. This provides the opportunity for this method to be used with specially designed micromanipulators to provide force as well as vision feedback for micromanipulation tasks.

[1]  Demetri Terzopoulos,et al.  Snakes: Active contour models , 2004, International Journal of Computer Vision.

[2]  G. K. Ananthasuresh,et al.  Vision-based Extraction of Geometry and Forces from Fabricated Micro Devices , 2000 .

[3]  John F. Canny,et al.  A Computational Approach to Edge Detection , 1986, IEEE Transactions on Pattern Analysis and Machine Intelligence.

[4]  Alan L. Yuille,et al.  Feature extraction from faces using deformable templates , 2004, International Journal of Computer Vision.

[5]  Yu Zhou,et al.  Sensor-based microassembly of hybrid MEMS devices , 1998 .

[6]  Dmitry B. Goldgof,et al.  Efficient Nonlinear Finite Element Modeling of Nonrigid Objects via Optimization of Mesh Models , 1998, Comput. Vis. Image Underst..

[7]  Gaudenz Danuser.  Observing Deformations of 20 Nanometer with a Low Numerical Aperture Light Microscope , 1996 .

[8]  Bradley J. Nelson,et al.  A flexible experimental workcell for efficient and reliable wafer-level 3D micro-assembly , 2001, Proceedings 2001 ICRA. IEEE International Conference on Robotics and Automation (Cat. No.01CH37164).

[9]  Fumihito Arai,et al.  3D nanorobotic manipulations of multi-walled carbon nanotubes , 2001, Proceedings 2001 ICRA. IEEE International Conference on Robotics and Automation (Cat. No.01CH37164).

[10]  Robert Barrett,et al.  Atomic force microscopy using a piezoresistive cantilever , 1991, TRANSDUCERS '91: 1991 International Conference on Solid-State Sensors and Actuators. Digest of Technical Papers.

[11]  Dimitris N. Metaxas.  Physics-Based Deformable Models , 1996 .

[12]  W. G. Bickley.  Mathematical Theory Of Elasticity , 1946, Nature.

[13]  Garret N. Vanderplaats,et al.  Numerical optimization techniques for engineering design , 1999 .

[14]  Gaudenz Danuser,et al.  Observing deformations of 20 nm with a low-numerical-aperture light microscope , 1996, Other Conferences.