Investigated the application of a multiplexed LED array to dark-field microscopy with human embryonic stem cells. The array I created was retrofitted inside of a Nikon SMZ-U microscope, and is now being compared to existing methods of cell illumination.

1. LED Stereomicroscope
Retrofit Project
Michael Ronzetti
MStem Cell Laboratories

2. The Project
• Mirror assembly and lamp in
Nikon SMZ-U microscope no
longer functioned.
• Provided perfect opportunity to
attempt a retrofit.
Requirements:
• Darkfield capability fro
35/60mm cell culture dishes
• Fit inside existing base.
• Low cost.

3. Darkfield with an LED array
• By illuminating the corners of
an array of LEDs, one can
theoretically create dark field
illumination of the object.
• I chose a 8x8 array to lower
costs.
Zheng, G., Kolner, C., & Yang, C. (2011). Microscopy
refocusing and dark-field imaging by using a simple
LED array. Optics Letters.

4. Multiplexed Array
• In order to individually control
each LED without 64 signal
wires, the array must be
multiplexed with the
SN74HC595 chip.
• Allows for three wires to
individually address any of the
LEDs.

5. Prototype
• Total cost of the custom board
+ components < $100
• Currently testing for accuracy
of the image against existing
illumination methods.