Since the early 20th century, cell culture techniques in biology labs have remained largely unchanged. Living cells and nutrients are put into a lab dish and then are placed inside a traditional incubator, a heating compartment that is typically the size of a small refrigerator. Within the unit, the researcher must maintain a constant temperature, an environment free of contaminants and the proper levels of humidity, oxygen and carbon dioxide. Whenever the lab dish is removed for observation or experiments, however, these optimal conditions are disrupted, and the cells begin to die.
In contrast, the thumb-size system developed by the Johns Hopkins engineers is self-contained and requires no external heating source. A drop of liquid containing living cells is injected into a port and flows through one of the microfluidic channels. A nutrient solution the cells food is also added in this manner.
The cells gravitate toward and stick to the surface of the microchip. The chip contains a simple heating unit a miniature version of the type found in a common toaster and is equipped with a sensor that continually checks to make sure the proper temperature is maintained. For human cells, this is usually 37 degrees Celsius or 98.6 degrees Fahrenheit. The chip is connected to a computer that controls the sensing and heating process. The prototype is connected to a computer via a hard wire, but the inventors say a wireless version would be the next step.
A gas-permeable membrane on the incubator allows the microsystem to exchange carbon dioxide and oxygen but keeps out bacteria that could contaminate the cell culture. If a cell colony grows too large, an enzyme can be injected into one of the microfluidic ports to detach and flush away surplus cells without destroying the primary cell culture.
The incubators small size provides several advantages, the researchers say. The unit can easily be moved to
|Contact: Phil Sneiderman|
Johns Hopkins University