Lab Manual: Atomic Force Microscopy (AFM)

AFM Apparatus

Objectives and learning goals

• Learn function of the 20.309 AFM and the relationships between its components.
• Understand how to extract quantitative information from this tool.
• Use the AFM to estimate the value of a fundamental physical constant.
• Possibly to take images, probe sample stiffness, and/or perform protein pulling.
• Analyze sources of uncertainty and noise in the system that limit the accuracy of measurements.

Roadmap scenarios and milestones

The AFM can be used both for A basic "mini-lab" homework problem, and also for more involved projects. This section will outline the mini-lab and provide one possible outline for extended, for instance as a final project. You are encouraged to devise much more creative uses for the AFM in final projects and beyond.

AFM mini-lab

1. Work with a TA or Instructor.
2. Learn the signal paths and connections of the system.
3. Practice aligning the AFM optics.
4. Learn how to calibrate the AFM to extract useful physical data.
5. Measure the vibrational noise floor in the AFM system.
6. Use the AFM to record the vibrational noise spectrum of a cantilever probe (Experiment ##)

Extended AFM work

1. Image several different samples with the AFM and measure physical dimensions of imaged features.
2. Use the AFM to measure the elastic modulus and surface adhesion force of several different samples.
3. Use the AFM and a gold-cotaed tip to pull and unravel proteins to determine their structures.