A microfabricated electrochemical oxygen generator for high-density cell culture arrays

We present a silicon microfabricated electrolytic oxygen generator for use in high-density miniature cell culture arrays. The generator consists of Ti/Pt electrodes patterned at the narrow end of conical hydrophilic silicone microchannels filled with electrolyte. Surface tension forces arising from the conical microchannel geometry push generated gas bubbles away from the electrodes and down the microchannel where the bubbles exhaust into the cell culture. This bubble motion draws fresh electrolyte from an adjacent reservoir onto the electrodes. The oxygen dosage can be precisely controlled in each generator by pulse width modulation of the electrode potential. We demonstrate devices capable of continuously providing for a wide range of oxygen demands (0-10 μmol O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /hr) and operating for days. Lifetime-limiting corrosion of hydrogen-absorbing noble metal electrodes during low-frequency electrolysis can be avoided by using relays to control the electrode potential. Precure silicone additives are also presented as an alternative to plasma surface modification to obtain hydrophilic silicone surfaces.