Caltech engineers build ‘smart’ Petri dish

Published: 9-Nov-2011

Device can be used for medical diagnostics to image cell growth


Engineers at the California Institute of Technology (Caltech) are using imaging sensor chips of the type used in mobile phone cameras to transform the way cell cultures are imaged by serving as the platform for a “smart” petri dish.

The ePetri device is described in a paper that appears in the Proceedings of the National Academy of Sciences (PNAS).

Biologists have used Petri dishes primarily to grow cells since the 1800s. In the medical field, they are used to identify bacterial infections, such as tuberculosis. Conventional use of a Petri dish requires that the cells being cultured are placed in an incubator to grow. As the sample grows, it is removed from the incubator to be studied under a microscope.

This is not the case with the ePetri dish.

“Our ePetri dish is a compact, small, lens-free microscopy imaging platform,” explained Guoan Zheng, lead author of the study and a graduate student in electrical engineering at Caltech. “We can directly track the cell culture or bacteria culture within the incubator.

“The data from the ePetri dish automatically transfers to a computer outside the incubator by a cable connection. Therefore, this technology can significantly streamline and improve cell culture experiments by cutting down on human labour and contamination risks."

The team built the platform prototype using a Google smart phone, a commercially available mobile phone image sensor, and Lego building blocks.

The scientists placed the culture on the image-sensor chip and used the phone's LED screen as a scanning light source. The device is placed in an incubator with a wire running from the chip to a laptop outside the incubator.

As the image sensor takes pictures of the culture, that information is sent to the laptop, enabling the scientists to acquire and save images of the cells as they are growing in real time.

The technology was found to be particularly adept at imaging confluent cells – those that grow very close to one another – and typically cover the entire Petri dish.

In addition to simplifying medical diagnostic tests, the ePetri platform may be useful in various other areas, such as drug screening and the detection of toxic compounds. It has also proved to be practical for use in basic research.

The Caltech team believes the ePetri system is likely to open up a whole range of new approaches to many other biological systems. For example, it could provide microscopy-imaging capabilities for other portable diagnostic lab-on-a-chip tools. The team is also working to build a self-contained system that would include its own small incubator.

You may also like