Caltech's ePetri dish uses Android, not microscope

Using an Android smartphone, a commercially available cell phone image sensor, and Legos, researchers take one giant leap in the 100-year-old world of the Petri dish.

What do you get when you combine an Android smartphone, cell phone image sensor, Lego building blocks, and a handful of Caltech engineers and biologists? The ePetri, which isn't Petri Dish 2.0, but a full reworking of a technology that dates back to the late 1800s.

The culture is placed on the image-sensor chip, and the phone's LED screen is used as a scanning light source. Guoan Zheng/Caltech

Traditionally, the Petri dish (named after German bacteriologist Julius Richard Petri) has been used in the medical field to identify bacterial infections by studying samples via microscope as the cultured cells grow in an incubator.

The Caltech researchers have a few choice words for such an approach in 2011, including "expensive," "labor-intensive," and "suboptimal." So they set out to improve not just the dish, but the entire process.

First, the ePetri platform does not require bulky and expensive microscopes. The culture is simply placed on an image-sensor chip, and the smartphone's LED screen acts as the scanning light source.

Next, the entire device is placed in an incubator, and connected by a wire from the chip to a laptop just outside. As the sensor images the culture, the resulting data is sent to the laptop, enabling the team to observe images in real time without having to go in and out of the incubator to image various points of growth.

Furthermore, the entire culture can be surveyed at once, without the focal point of a traditional microscope, which enables observers to zoom in and out of various points of the images without sacrificing resolution.

"With ePetri, you can survey the entire field at once, but still maintain the ability to 'zoom in' to any cells of interest," says biologist Michael Elowitz, who coauthored the team's study. "In this regard, perhaps it's a bit like an episode of CSI, where they zoom in on what would otherwise be unresolvable details in a photograph."

Because it's a platform technology, the team fully expects the system to be applied to other devices, such as microscopy-imaging for portable diagnostic lab-on-a-chip tools, and says it could open up an entire range of new approaches to other biological systems as well.

They've recently published their results in the Proceedings of the National Academy of Sciences, and are already working on a self-contained system that would include its own miniature incubator. Instead of sending bacteria samples out to a lab, one's doctor could have the entire "desktop" system right there in his or her office.

Watch ePetri in action below:

 

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