This would definitely fall under the category of things your smartphone can do that you will never use, but that could prove to be very valuable to scientists. You can read about all of the details of this cool new device on the Caltech website, but here are some of the highlights.
Petri dishes are probably the simplest and oldest tool used by biologists to grow cells and conduct studies on things such as bacteria. The ePetri dish allows for the same cell growth and observation but in a simpler, and in some ways more controlled, way.
The engineers at Caltech used a Google smart phone, a commercially available cell-phone image sensor, and Lego building blocks to build this simple, yet powerful device. I personally find it incredibly interesting that Legos were used in the ePetri dish as there are few people who have not let their imagination wander with Legos. To see them used on a device that could have such a tremendous impact is very cool.
The culture the scientist is studying is placed on the sensor and the whole device is placed into the incubator attached to a wire that runs to a laptop outside the incubator. This allows scientists to study the culture without removing it from the incubator and risking possible contamination.
In the past, scientists had to repeatedly remove their dishes to study them under microscopes. The ePetri dish allows for the same study to be done without the risk of contamination, and in a much less labor intensive manner.
In the long run, the engineers are hoping to broaden the technology to other research arenas. They are even hoping to develop a standalone device that includes the incubator allowing research to literally be done at any given desktop. Something that was impossible with the bulky, expensive microscopes that have been used up until now.