Fast-Track : Conductive Diamond Probes for Scanning Elecrochemical Microscopy

This Fast Track SBIR project aims at developing electrically insulated scanning probes suitable for high resolution electrical nano-imaging in conductive solutions. These probes, when used in atomic force microscopy, enable scanning electrochemical microscopy (AFM-SECM) to be performed. This method is increasingly important for the scientific study of applications including nano-electrodes for solar energy conversion, high capacity batteries, bio-interfaces, and oxidative nanolithography. Currently, such probes are produced by end users through their own efforts using technical approaches of limited scalability, manufacturability, and performance. We propose the batch fabrication of conductive diamond probes that are completely electrically insulated except at the tip apex. We will make them widely available at reasonable cost, with breakthroughs in quality, reproducibility and reliability. The batch fabrication extends an existing Advanced Diamond Technologies platform technology for nanoscale probes, NaDiaProbes and builds on a well-established collaboration with the University of Pennsylvania (Penn). Our new strategy will integrate silicon dioxide insulation around the probe tips. Electrical contact to the conductive probe core will be facilitated by a glass handling chip with through-hole metallization. The use of boron-doped ultra-nanocrystalline diamond (UNCD) as the tip material offers an exceptionally wide electrochemical window, no oxidation or hysteresis during operation, and the highest nanoscale wear and corrosion resistance of any material. Phase I (9 months) will develop and characterize a prototype batch of probes in house and at Penn, with certain specifications for admission in Phase II. Phase II (12 months) will start with beta testing the prototype probes with heavy users of SECM in parallel with running more specific tests in AFM- SECM mode, including wear tests. The collected data and the feedback from the beta tests will lead to a final revision of the product, while also defining the future catalogue specifications of the probes. Phase II will end with a series zero fabrication of the enhanced probes, their evaluation to pass/fail established specifications criteria, and the onset of sales. The proposed diamond nanoprobes will substantially exceed the performance of in-house built probes by existing groups, and will extend the application field to higher-conductivity electrolytes, higher voltages, more corrosive media, higher temperatures. They will guarantee a stable and long lasting imaging capability through the proven low-wear properties of diamond. These probes will provide a necessary tool for the development of advanced solar cells, rechargeable batteries, bio- electrochemical interfaces, implantable devices, complex bio-sensors, pore-based molecular sieves, and nanofabrication processes based on electrochemical etching or growth, all of which share a common requirement for better understanding of electrode phenomena at the nanoscale.