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A Fine Measurement Machine Integrating Nanotechnology into the K-12 STEM Curriculum Mort Sternheim: [email protected] Rob Snyder: [email protected] In spite of their different goals, science and technology have become closely, even inextricably, related in many fields. The instruments that scientists use, such as the microscope, balance, and chronometer, result from the application of technology/engineering........ Page 8: http://www.doe.mass.edu/frameworks/scitech/1006.doc Atomic Force Microscopes (AFMs) are used to make nanoscale measurements http://en.wikipedia.org/wiki/File:Atomic_force_microscope_by_Zureks.jpg An AFM generated this image of the ionic crystal lattice array of sodium chloride. http://en.wikipedia.org/wiki/Image:AFM_view_of_sodium_chloride.gif This example of a schematic drawing reveals some essential components of an AFM. http://en.wikipedia.org/wiki/Image:Atomic_force_microscope_block_diagram.png Key features of an AFM include: A flexible cantilever that exerts a small amount of downward force on an object so that the object is not damaged. A mirror that creates a long pathway for reflected light to travel so that the motion of the tip at the and of the cantilever is multiplied. A lever mechanism can model the process of making measurements with an AFM. Ruler Laser Pointer Hanging mass mirror Lever support The activity document provides directions for: • Assembling a lever mechanism that can measure the thinness of an object. • Calibrating the lever mechanism. • Determining how much the level mechanism multiplies motion. • Developing a strategy to map an uneven surface. If a thin object moves under one end of the lever arm, it causes the lever arm to move a short distance and the point of light on the ruler moves a greater distance. The reflected light beam now reaches a different point on the ruler. A hanging mass can be placed in a position on the short arm of the lever so that the long lever arm does not exert a lot of downward force on the object that is being measured. The lever needs to be able to respond to subtle changes in thinness. An object of a known thinness can be used to calibrate the measurement machine. The calibration reveals the relationship between the movement of the lever and the movement of the point of light on the ruler. Tasks for team members to accomplish. • • • • • • • Organize a work area. Coordinating your group’s movements with other groups. Assembling the machine. Managing the experimental procedure. Working with the laser pointer carefully. Collecting and recording data. Keeping the lever assembly stable. The Analyzing Pathways of Light document explores the laws of reflection. Normal Line Angle of Reflection Angle of Incidence Mathematical relationships can be discovered. d2 laser Long light path and a short cantilever gives large amplification L2 cantilever d1 L1 The distance amplification d2/ d1 is proportional to L2/ L1 pivot point . The Balanced Torques document explores another aspect of a lever mechanism. Point of Rotation Some questions How was the fine measurement machine similar to the design of an Atomic Force Microscope? How was the fine measurement machine different from the design of an AFM? Why do we need to minimize the amount of downward force acting on an object being mapped? A Few More Questions How do you know when the measurement machine reaches an equilibrium? What forces are involved when the model of an AFM is mapping an object? What additional technologies are associated with using an AFM to collect data? How would you change the design of the measurement machine to make it more effective? UMass Amherst Nanotechnology Curriculum Resources are available at http://umassk12.net/nano/ Examples of Activities, Teacher Guides, Worksheets, PowerPoints and Multimedia Module Include: The Fine Measurement Machine as a model of an Atomic Force Microscope An Oleic Acid Thin Film Activity Nanoscale Electrodeposition Gel Diffusion The Nanotechnology of Sunscreen Nanoscale Powers of Ten