1 / 16

Physical Science Lesson 7 How Do We Measure Forces at the Nanoscale Level?

Investigating Static Forces in Nature: The Mystery of the Gecko. Physical Science Lesson 7 How Do We Measure Forces at the Nanoscale Level?. Probes. What are some instruments (probes) you have used in previous science classes?.

noura
Download Presentation

Physical Science Lesson 7 How Do We Measure Forces at the Nanoscale Level?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Investigating Static Forces in Nature: The Mystery of the Gecko Physical Science Lesson 7 How Do We Measure Forces at the Nanoscale Level?

  2. Probes What are some instruments (probes) you have used in previous science classes?

  3. Insert the probe in an area of the box with no object (9.0 cm) Insert the probe in an area of the box with the object (8.6 cm) The height of the object at that point is the difference (9.0 cm - 8.6 cm = 0.4 cm) How to Measure the Height of an Object With a Probe Image 7.5

  4. Making a 3-D Representation Based on the height data gathered from your probing activity, use a spreadsheet program to make a 3-D representation of the unseen surface. Image 7.6

  5. sharp tip cantilever Atomic Force Microscope Image 7.7 Image 7.8 AFM measures/images topography of surface: deflection of cantilever proportional to height of surface feature

  6. Comparison of AFM and Box Model

  7. Question: How do gecko spatulas of a seta affect the amount of surface contact? Modeling a Gecko Seta Image 7.9 Image 7.10 One gecko seta Many spatulas on the top of one gecko seta

  8. Possible Setup Image 7.11 Image 7.12 Image 7.13 Image 7.14

  9. apparent contact area real contact area Soft – Transparent Tape Hard – Desk Top Compliant Surfaces If one or both surfaces are compliant : Image 7.15

  10. Spatulas on Surfaces Image 7.17 Image 7.16

  11. Look back at your previous methods (from lessons 5) as to how the gecko adheres to a wall. Are there some that you could eliminate because of the new information you now have? Are there any new interpretations you would add? What new questions do you have about surface-to-surface interactions? Journal Prompts

  12. How could the force between one gecko seta and a surface be measured? Seta slides on the surface and builds up larger adhesion forces Micro-Electro-Mechanical System (MEMS) Probe Cantilever Pull Direction Single Gecko Seta Measuring Tiny Forces Image 7.18 Image 7.19

  13. Typical Lateral Force Curve Image 7.20

  14. Adhesion Hypothesis • Dense arrays of “spatulas” conform to match topography of an opposing surface. Image 7.22 Tip of one gecko seta Image 7.21

  15. How are AFM and the MEMS devices used to help understand gecko adhesion? What do we now know about the amount of force between a single seta and a surface? How does this new information help us understand the adhesion method for the gecko? What should we explore next? Making Connections

  16. Flow Chart 1. How Can a Gecko Walk on a Ceiling? Scale: Visible Dominant Force: Gravity Tools: Eye 2. What Do We Mean When We Speak About Surfaces in Contact? Scale: Visible Force: Gravity Tools: Eyes 3. What Are Your Ideas About Small Sizes? Scale: Visible/Invisible Dominant Force: Varies Tools: Eyes, Instruments 4. What Do We Learn When We Look More Closely? Scale: Invisible Dominant Force: Extremely Small, Large in Number Tools: Special instruments (scanning tunneling microscope) 6. How MUCH Force Is Needed to Make an Object Stick? What Factors Affect the STRENGTH of Force Acting? 5. What Types of Forces Can Hold Objects Together? Scale: Visible/Invisible Dominant Force: Gravity Tools: Eyes and Hands • How Do We Measure Forces at the Nano Level? • Scale: Visible and Invisible • Dominant Force: Extremely Small, Large in Number • Tools: Atomic Force Microscope 8. How Can a Gecko Walk on a Ceiling?

More Related