A camera-attached laboratory microscope: $2,500.
An imaging chip, a smartphone, and some Lego blocks: $400.
Scientists at Caltech, out to ruin microscope manufacturers, have built their own device to monitor cells growing in a Petri dish. The device – which they call an ePetri dish – does away with the normal habit of taking the Petri dish out of the incubator and inspecting them under a microscope. Instead it takes images of the entire dish surface over time from inside the incubator. Without ever disturbing the cells they're trying to grow, researchers can now take these cell growth "movies" and replay them whenever they want.
With the ePetri system, cells are grown on a CMOS image sensor – the kind found in common digital cameras. A smartphone placed above the sensor provides – via a commercially available app – a scanning spot of light that sweeps back and forth across its LED screen. Legos provide an enclosure that the smartphone rests on (no Lego NXT needed here). The contraption sits inside the incubator while a wire connects the sensor to laptop outside. Pictures are taken by the sensor and transferred to the laptop. With the ePetri system, scientists no longer have to remove the cells from the incubator but can simply look at the laptop images. Less manipulation makes for better cell health and reduced risk of contaminating them.
It also cuts down on work. Peering through a microscope limits visual range to a very small section of the Petri dish. Because ePetri scans the entire dish at a resolution of about half a micrometer – plenty of mag to see single cells. With the ePetri system scientists have the option of viewing the entire culture at once or zooming in to visualize single cells. And the continuous scanning capability means they get to watch their cells change in realtime.
Michael Elowitz, a professor of biology and bioengineering at Caltech and a co-author of the study, thinks ePetri is a game changer. “It radically reconceives the whole idea of what a light microscope is,” he said in a press release. “Instead of a large, heavy instrument full of delicate lenses, [we] have invented a compact lightweight microscope with no lens at all, yet one that can still produce high-resolution images of living cells.”
A lab member prepares an ePetri dish in the following video. He does his best not to speak, but I’m sure he’s very excited.
Elowitz and his colleagues gave ePetri a test run by using it to monitor the growth of stem cells. With it they were able to track the cells as they differentiated across the entire dish surface – an extremely labor-intensive and time-consuming undertaking with the use of a single microscope. They published the study recently in the Proceedings of the National Academy of Sciences.
Beyond monitoring cell growth, the ePetri scientists envision using the system to monitor other devices such as lab-on-a-chip tools. They also think doctors could use the system to test bacteria samples right there in the office instead of sending them out to a lab for testing. Currently the team is looking to make the ePetri dish a self-contained system by giving it its own small incubator. Of course, if they use anything but ziplock bags and soda cans it simply won’t be as cool.