A microsystem for sensing and patterning oxidative microgradients during cell culture

We present the design, modeling, fabrication and testing of a microsystem for the electrolytic patterning and sensing of oxidative microgradients within 161 mm 2 area during cell culture. The system employs an array of microfabricated electrodes (3-40 mu m in width) embedded in gas-permeable microchannels to generate precise doses of dissolved oxygen ( ranging from 10 fmol O-2 mm(-2) s(-1) to 100 nmol O-2 mm(-2) s(-1)) via electrolysis. The microgradients generated by different microelectrodes in the array can be superimposed to pattern multi-dimensional oxygen profiles not possible with other methods. We demonstrate the patterning, sensing and quantification of dissolved oxygen microgradients in the 0 to 40% dO(2) range using this microsystem. Reactive oxygen species generation and dosing is also quantified. Lastly, we demonstrate how the microtechnology enables new types of experiments in three different cell culture models: localized hyperoxia-induced apoptosis in C2C12 myoblasts, dynamic aerotaxis assays of Bacillus subtilis, and studies of calcium release in an ischemia/re-oxygenation myoblast model.