Despite all the huge advances in medical technology in the past couple centuries, petri dishes, one of the most crucial pieces of equipment, haven’t changed much at all. Now a grad student at Caltech has finally brought these flat-bottomed bowls into the 21st century.
The new device, dubbed ePetri, uses an imaging chip from a mobile phone camera, a smartphone and Lego blocks. The imaging chip acts as the petri dish in the traditional sense, holding the cell culture beneath a sheet of protective plastic. The square chip is placed inside a platform made of Legos, and an Android phone hooks in place on top. The phone’s LED screen is used as a scanning light source, illuminating the image sensor.
The whole thing goes inside an incubator, and a cable connects to a computer outside, which reads the image sensor. This allows researchers to watch cell growth in real time — no extra cell transport, pipetting or external microscopes required. Watch a video below to see how well the system works.
Cell culture involves lots of cell transport, moving from incubators to microscope plates and back again. The process is time-consuming and laborious, so any processes that can automate cell culture would be a welcome advance. It also cuts down on contamination risks, explains Guoan Zheng, an electrical engineering grad student and lead author of the paper describing the ePetri.
The ePetri allows wide-field images of confluent cells, which are cells that grow tightly together. Other Caltech scientists have already put it to the test, according to a news release from the university: Biologist Michael Elowitz used it to observe embryonic stem cells. Stem cells differentiate in different ways, so a biologist looking through a microscope would only be looking at one small group, akin to wearing blinders. But the ePetri let Elowitz study stem cells on the entire device.
“It radically re-conceives the whole idea of what a light microscope is,” he said.
The team believes the ePetri could be used for labs-on-a-chip or other portable diagnostic devices, according to Caltech. Zheng and colleagues are working on a new self-contained version that includes a small incubator, which would be useful for diagnostic tests that would not require sending samples out to a lab.
The ePetri is described in the online version of the Proceedings of the National Academy of Sciences.