A Fine Measurement Machine Integrating Nanotechnology into the K-12 STEM Curriculum Rob Snyder:

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:

Atomic Force Microscopes (AFMs) are used to make nanoscale measurements This is an AFM at the Center for Hierarchical Manufacturing at the University of Massachusetts Amherst.

An AFM generated this image of the ionic crystal lattice array of sodium chloride.

Mark Tuominen is the Co-Director of the CHM at UMass Amherst In this demonstration, he uses a laser pointer to show how an AFM uses a reflected beam of light to make nanoscale measurements.

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. 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.

This was our first attempt to have students model the process of making measurements with an AFM. This design was based on an article that appeared in the December 2006 issue of Science Teacher.

Our beta version made use of a simple first class lever.

A lever measurement device has a number of components. Laser Pointer Ruler Lever support mirror Hanging mass

A students 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 a point of light on a wall ruler moves a greater distance. If a thin object moves under one end of the lever arm. It causes the lever arm to move a short distance and a point of light on a wall ruler moves a greater distance. The reflected light beam now reaches a different point on the ruler.

A hanging mass needs to be placed in a position on the short arm of the lever so that the end of 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. 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. Shims of know thicknesses can be used to calibrate the measurement machine.

Tasks for team members to accomplish. Organize a work area. Coordinating your groups 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.

Students have an opportunity to assemble a device.

Activities like this can build a problem solving team approach as students manage the experimental process.

Students can develop a s strategy for measuring the angles of incidence and reflection. Angle of Incidence Angle of Reflection Normal Line ruler

A reflected beam of light needs to be located on a scale and its movement needs to be measured carefully.

Data needs to be recorded and analyzed.

Mathematical relationships can be discovered.. cantilever laser Long light path and a short cantilever gives large amplification d1d1 d2d2 L1L1 L2L2 pivot point The distance amplification d 2 / d 1 is proportional to L 2 / L 1

Students can explore how extending the path of light affects the measurement process. ruler Another Mirror Ruler

A Balanced Torques activity document explores an important aspect of a lever mechanism. Point of Rotation This activity includes calculating the weight of the hanging mass and the mirror.

A few examples of assessment questions How was the fine measurement machine similar to and different from the design of an actual Atomic Force Microscope? Why do we need to minimize the amount of downward force acting on an object being mapped? How was the fine measurement machine similar to and different from the design of an actual Atomic Force Microscope? How do you know when the fine measurement machine reaches an equilibrium? Why do we need to minimize the amount of downward force acting on an object being mapped? What forces are involved when the model of an AFM is mapping an object? How would you change the design of the fine measurement machine to make it more effective?

An AFM has even been transported to Mars. This image presents data from the AFM on NASA's Phoenix Mars Lander. It shows surface details of a substrate on the microscope station's sample wheel. It will be used as an aid for interpreting later images of minuscule Martian soil particles. Source: M_on_MARS.html M_on_MARS.html