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.