light control of phototactic microswimmer suspensions connor hann, danielle riggin, janan zhu duke...

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 fr

om 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