Bubbles and Biosensors
Students work in groups to create soap bubbles on a smooth surface, recording their observations from which they formulate theories to explain what they see (color swirls on the bubble surfaces caused by refraction). Then they apply this theory to thin films in general, including porous films used in biosensors, listing factors that could change the color(s) that become visible to the naked eye, and learn how those factors can be manipulated to give information on gene detection. Finally (by experimentation or video), students see what happens when water is dropped onto the surface of a Bragg mirror.
Thin films use refraction and interference to create colorful patterns.Copyright Lawrence Berkeley National Laboratory U.S. Department of Energy http://www.lbl.gov/MicroWorlds/brightbusy/greiner.check.html
The ultimate job of engineers is to take known facts about our world and its physical composition, phenomena and natural laws, and apply that knowledge to the creation of solutions that have never existed before to meet a societal need. In this activity, students think like engineers by observing a physical phenomenon (color swirls in soap bubbles) and applying the concepts that drive this phenomenon to nanoscale biosensors, which could potentially meet a need for efficient gene detection.
After this activity, students should be able to:
- List three factors one could change to alter the visible color(s) of a thin film.
- Clearly explain in at least two complete sentences how each of the three factors alters the interference pattern to produce different colors.
- Describe in at least one complete sentence how a change in one of these factors alters a biosensor.