Light Control of Phototactic Microswimmer Suspensions

Connor Hann, Danielle Riggin, Janan ZhuDuke University

How Does Light Affect Algal Motion?

(

200 Hz Camera

LightSource

Red Light (Filter)

Microscope

Flow

1 mm

1 mm

Chlamydomonas Propels Itself In Fluid With Flagella

Flow at Low Speeds Creates Layers of Different

Velocities

z

This type of flow is called Poiseuille Flow.

Visualizing Poiseuille Flow

Chlamydomonas Moves in Response to Light

Eyespot

Visualizing Algal Flow

(

200 Hz Camera

LightSource

Red Light (Filter)

Microscope

Flow

1 mm

1 mm

Light Orientation Determines Direction of Motion

Light Alters Swimmer Movement

Mathematical Model Matches Data

Dis

tanc

e fro

m C

ente

r

Distance along Tube

Pollution Reduction

• 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

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

Acknowledgements