PHYS 257 Lecture Notes - Lecture 10: Piezoresistive Effect, Damping Ratio, Atomic-Force Microscopy
21 Feb 2018
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Document Summary
We can think of micro and nano mechanical objects as generalized mass-spring systems. But this equation excludes key parameters like damping. Damping is normally modeled by a velocity dependent term, this modifies the solution. Sinusoidal term represents an applied force, driving the system at resonance. Micro oscillator: rod with sharp tip at the end (cantilevers with tips) Can be thought of as two springs in series. Want a long lever so you can change the length. To measure frequency, you need to take many cycles to reduce error. Use laser spot that easy to detect. Optical interferometer (optical fiber over cantilever, send in laser beam which is reflected back can detect change in length in gap frequency decomposition) Optical beam deflection (reflect off cantilever when cantilever moves down, the beam is reflected at a different spot, so the change in position of where the beam reflects back shows the change in position of the oscillator)
