Fabrication Techniques for On-Chip Microelectrodes.

"Electronic integrated biochips are based on the post-processing of microelectrodes on silicon chips. Their aim is to provide the advantages of microfabrication (miniaturized features and batch production) to surface affinity assays. Major challenges in the development of microelectrodes-on-a-chip arise from the reliability issues in the liquid environment. A key factor is the quality of the passivation layer, which is required to electrically insulate the interconnections from the liquid so that only the desired areas of the electrodes are exposed. The groups led by Professor Carlotta Guiducci (Laboratory of Life Sciences Electronics) and Professor Yusuf Leblebici (Microelectronic Systems Laboratory) have designed and fabricated microelectrodes on Silicon featuring the same metal patterning, but passivated with different techniques (SiO2 sputtering, LPCVD low temperature oxide (LTO), parylene deposition, SU–8 coating, and dry-film lamination). The performance of these techniques has been evaluated by hydrolysis tests, impedance measurements, and electrochemical tests on self-assembled monolayer and on electrochemical labels. This study provides detailed fabrication descriptions of various microelectrode passivation techniques, proposes techniques to enhance the stability of the passivation layer, and presents the advantages and disadvantages of each method based on experimental validation."

See: Yuksel Temiz , Anna Ferretti , Yusuf Leblebici and Carlotta Guiducci, Lab Chip, 2012, DOI: 10.1039/C2LC40582B