On-chip CO2 incubation for pocket-sized microfluidic cell culture

We have developed an on-chip CO2 incubation system based on mass/heat transfer from aqueous solutions of bicarbonate source to cell culture media through a permeable poly(dimethylsiloxane) (PDMS) wall. Heating a carbonate-buffered bicarbonate solution successfully regulated CO2 generation without any feedback control. Because a microfluidic cell culture chip with the incubation system does not require an external chamber or gas supply, the entire microfluidic cell culture setup becomes pocket sized. Using 5 ml of 0.8 M sodium bicarbonate with 65 mM sodium carbonate as the water jacket, the chip maintained the temperature, osmolality, and pH of 750 mu l cell culture medium within physiological levels when the chip was placed on a 37A degrees C surface. The osmolality shift and pCO(2) of the media reservoir stabilized within < 5 mmol/kg and 5.0 +/- A 1.0% over at least 9 days. The incubation capabilities were demonstrated through microfluidic culture of COS-7 epithelial cells under an inverted microscope for 17 days.