October 4, 2007 – Researchers from Johns Hopkins U. have created a CMOS-based thumb-size microincubator to culture living cells for lab tests, offering a mobile yet still protected and relatively low-cost advancement over traditional biology lab equipment.

The achievement, detailed in the journal IEEE Transactions on Biomedical Circuits and Systems, describes an incubator with microchannels made from polydimethylsiloxane (PDMS) through which cells and nutrients can be transferred during experiments, with computer-controlled electronics maintaining the proper environmental conditions.

Traditional cell culture techniques involve putting living cells and nutrients into a dish inside a small-refrigerator-sized incubator, which keeps constant environmental conditions (temperature, humidity, O₂/CO₂ levels, etc). The samples need to be removed from the incubator (and those settings) to be examined.

This new thumb-sized system, though, is self-contained and its contents can be viewed under a microscope without disrupting those environmental conditions, the researchers report. Liquid drops with living cells and nutrients are separately injected into the port and flow through the microfluidic channels; the cells stick to the surface of a microchip, which contains a simple heating unit and a sensor to maintain proper temperature. The chip is hard-wired to a PC (a wireless version is the next step, the researchers noted). A gas-permeable membrane on the incubator allows the exchange of O₂ and CO₂ but blocks out contaminants (e.g. bacteria). Also, enzymes can be added via the microchannels to flush away any unneeded cells without destroying the primary culture. “Once it’s set up, you can just walk away,” notes Jennifer Blain Christen, the study’s lead author.

The small microincubator and its contents can be safely moved to different lab equipment for analysis, or even out into the field for testing. Also, “because it’s so small, we can change the temperature of the cell culture environment very quickly,” e.g. from room temperature to human body temperature (98.6°C) in <0.1sec, Christen notes in a statement.

The researchers say they’ve used the device to culture baby hamster kidney cells over a three-day period. Ultimately, they want the device to be able to image cells and tissue using optical light guides, and stimulate and gather information about cells’ electrical activity.

IMAGE CAPTION: a) The micro-incubator features a network of tiny fluid channels and a miniature sensor-guided electric heater to maintain the proper temperature to culture cells. b) The inner workings of the micro-incubator. (Source: Johns Hopkins U.)