Fabrication of iridium oxide pH sensors and sensory arrays

A method for fabricating a sol-gel based iridium oxide pH sensor comprising steps of:

• forming a microfluidic mold by pouring a polymer on a patterned mold, wherein the formed microfluidic mold comprises at least one micro-dispensing channel, wherein the at least one micro-dispensing channel comprises a plurality of micro-dispensing channels;
• curing the polymer to form the microfluidic mold;
• forming at least one reservoir in the microfluidic mold, wherein the at least one reservoir has a pathway to the at least one micro-dispensing channel;
• peeling the microfluidic mold from the patterned mold to thereby form a polymeric layer comprising the at least one reservoir and the at least one micro-dispensing channel, wherein the at least one reservoir extends through a top opening at a top wall of the polymeric layer, the at least one reservoir comprising a diameter at the top opening of the polymeric layer, wherein the diameter is sized to allow passage of a solution through the pathway to each one of the at least one micro-dispensing channels;
• aligning the polymeric layer on top of a substrate comprising at least one electrode, the at least one electrode comprising at least one metal layer,
• wherein aligning the polymeric layer with the at least one electrode comprises aligning each one of the at least one micro-dispensing channels in the polymeric layer with each one of the at least one electrodes on the substrate such that each one of the at least one micro-dispensing channels contact each one of the at least one electrodes and a distal dispensing end of each one of the at least one micro-dispensing channels is configured to deposit the solution onto a dispensing site of each one of the at least one electrodes;
• dispensing an iridium oxide sol-gel solution into the top opening of the at least one reservoir such that each one of the at least one micro-dispensing channels deposit the iridium oxide sol-gel solution onto the dispensing site of each one of the at least one electrodes to create a pH sensing electrode comprising iridium oxide;
• removing the polymeric layer from the pH sensing electrode;
• coating the pH sensing electrode with a photoresist layer and photolithographically creating a pattern;
• depositing a second layer of metal, wherein the second layer of metal consists of a first layer of chromium and a second layer of silver;
• and
• lifting off the photoresist layer.