All Done with Mirrors: Smart Substrates for 3D Views

Dr. J. Alexander Liddle

Dr. Matthew McMahon, Dr. Andrew Berglund,

Dr. Peter Carmichael, Dr. Jabez McClelland

Benefits/Advantages• Microfabricated substrates can be combined with most other

optical microscopy techniques– Simple– Easy to make– Add lots of information

• Function: Resolve ambiguity– Same positions when viewed from above, but different heights

• Application: Put cell inside sample well– Rapid screening of cell height– Modest-resolution, high-throughput 3D information

What Motivated the Research?

Cui, Björk, Liddle, Sönnichsen, Boussert & Alivisatos

Nano Lett. 2004, 1093

Solution-Based Nanoparticle Assembly

3D Imaging in Optical Microscope

• Goal: Monitor/Measure Dynamics by Seeing in 3D– Track assembling particles in

as close to real-time as possible• The smaller they are, the faster

they move

• How?

2D Track from 2D Images

• 2D tracks easily constructed from 2D video– Special software needed to get accurate particle positions

• Some codes available free

The ideal would be…

Oh well…hmmm….

Orthogonal Tracking Microscopy

a

c

b

obj . 1

obj . 2

mirror chamber

a

c

b

obj . 1

obj . 2

chamber

Reduce the problem of tracking in 3Dto the problem of tracking in 2D twice

MICROFABRICATED SAMPLE CHAMBER WITH INTEGRATED REFLECTIVE OPTICS

Si

Software Enhances Technology

• New algorithms developed that are fast and can handle complicated shapes

Easy Difficult

Demonstration• All-silicon substrate

• Squares defined by photolithography

• Anisotropic etch of Si by KOH: 54.7° sidewalls

• Pyramidal indentations

Movie: 190 nm fluorescent polystyrene sphere in water

Future Development

• Hardware:– Integrate more complex optical elements

• Better mirrors (i.e. gold)• Filters• Polarizers• Diffractive elements

• Software– Explore asymmetry

• Asymmetric objects: rotational motion• Asymmetric radiation patterns

Summary

• Microfabricated substrates can be combined with most other optical microscopy techniques

• Resolve ambiguity– Same positions when viewed from above but different heights

• Put cell inside sample well– Rapid screening of cell height– Modest-resolution, high-throughput 3D information

• A patent application covering the concept of using microfabricated optics to permit imaging in 3D is pending.