Introductory Laboratory Category

2002 AAPT Apparatus Competition, Boise State University

Name: Matthew T. Smith

Address: 7301 Foothill Drive

Lake Point, UT 84074

Phone: 801-508-7069

Fax:

E-mail:

Apparatus Title: Atomic Force Microscope Model

Abstract (40-50 words)

We have constructed a simple model of an Atomic Force Microscope that will fit into any highschool teachers budget. The model keeps the electronics to a minimum while providing a great tool for teaching students the nature of science. While many laboratory activities and inquiry assignments are decontectualized and must be tied to science through analogies and metaphors, this model will enable students to discover the nature of science by using an apparatus similar to those actually used in research science.

Description

The mechanical set up of the model is similar to an AFM but much simpler. The weight of the cantilever is what keeps the tip in contact with the sample. A laser is bounced off the cantilever and up to a photodetector which is easily constructed with two phototransistors set against each other. As the sample is moved under the tip the position of the beam on the detector is centered more or less on one of the phototransistors. Peaks on the surface of the sample will register as positive voltages while valleys register negative. Plotting voltage vs. time gives us an image of the surface of the sample.

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