1. Light Control of Phototactic Microswimmer Suspensions Connor Hann, Danielle Riggin, Janan Zhu Duke University

2. How Does Light Affect Algal Motion? ( 200 Hz Camera Light Source Red Light (Filter) Microscope Flow 1 mm

3. Chlamydomonas Propels Itself In Fluid With Flagella

4. Flow at Low Speeds Creates Layers of Different Velocities z This type of flow is called Poiseuille Flow.

5. Visualizing Poiseuille Flow

6. Chlamydomonas Moves in Response to Light Eyespot

7. Visualizing Algal Flow ( 200 Hz Camera Light Source Red Light (Filter) Microscope Flow 1 mm

8. Light Orientation Determines Direction of Motion

9. Light Alters Swimmer Movement

10. Mathematical Model Matches Data Distance from Center Distance along Tube

11. Pollution Reduction

12. Light was used to focus algae in a flow A model was created that successfully explained the focusing This technique can be applied to detecting pollution Conclusions

13. Xabel Garcia, Salima Rafaı, and Philippe Peyla, Light Control of Phototactic Microswimmer Suspensions Phys Rev Letters 110:138106(1-5), 2013. Acknowledgements