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Cover of Scientific American , October 2003

Cover of Scientific American , October 2003. Actuator driven by thermal expansion of water and air. Source: www.ritsumei.ac.jp. A chemical reaction with methanol creates heat in the NiTi alloy wire, which causes it to shrink - thus lifting a weight. Example of negative thermal expansivity!.

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Cover of Scientific American , October 2003

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  1. Cover of Scientific American, October 2003

  2. Actuator driven by thermal expansion of water and air Source: www.ritsumei.ac.jp

  3. A chemical reaction with methanol creates heat in the NiTi alloy wire, which causes it to shrink - thus lifting a weight. Example of negative thermal expansivity! V.H. Ebron et al., Science (2006) 311, 1580

  4. The AFM probe is exceedingly sharp so that only a few atoms are at its tip! Weak Nano-scale Forces Can be Measured Atomic force microscope (AFM) Sensitive to forces on the order of nano-Newtons.

  5. F Tips for Scanning Probe Microscopy The tip is on a cantilever, which typically has a spring constant on the order of k = 10 N/m. Modelled as a simple spring: F = kz where z is the deflection in the vertical direction. Radius of curvature ~ 10 nm Ideally, one of the atoms at the tip is slightly above the others. AFM tips from NT-MDT. See www.ntmdt.ru

  6. C A B C E D Measuring Attractive Forces at the Nano-Scale A = approach B = “jump” to contact C = contact D = adhesion E = pull-off Tip deflection  Force Vertical position

  7. Measuring Force of Attraction to a Polymer Surface Pushing on AFM probe tip Pulling on the AFM probe tip

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