Aerogels for 3D Integration of Nanoelectronics Rachel A. Berezik, Mary E. Summers, Thomas H. LaBean North Carolina State University, Department of Materials Science & Engineering Introduction Methods Conclusion A long-term goal for DNA nanotechnology is to use DNA to enable self-assembling nanoelectronics with single electron transistors from the bottom up Our goal is to make an electrically conductive aerogel network out of agarose and carbon nanotubes (CNT’s) for this application Want to find percolation limit, or the concentration threshold at which there is no more conductivity Want to make composite aerogels that show even dispersion of CNT’s, durability and other mechanical properties, and conductivity Agarose Hydrogels: Not widely used for this application, but proven the best among other gel materials for its economic feasibility and ability to maintain form throughout processing 3% agarose gels and CNT composite hydrogels Vary CNT concentration around percolation limit while retaining continuous electrical conductivity Prepared gel solution (agarose powder, water, and CNT’s), poured into mold, and let solution set Gels were observed to be very rubbery, light-weight, and opaque before undergoing critical point dyer Ethanol Exchanges: This step ensures that gels are of pure condition before being placed into critical point dryer 10% ethanol increase every 1.5 hours After reaching 100% ethanol, the gels were placed in 50-50 ethanol-acetone solution Critical Point Dryer: Creates an aerogel by systematically removing liquid Ethanol and acetone are standard critical point drying solvents Resulting gels were success if they maintained size and shape, but were aerated and light weight Need to tune CNT concentration throughout aerogels and corresponding conductivities Want to see individual CNT’s and networks of those nanotubes touching (top figure) Right now, seeing many of them associating with one another (bottom figure) + H2O + heat Microstructure of agarose (Ao, et al.) EtOH CO2 Agarose with CNT contact points Future Apply DNA self-assembly in aerogel networks Use single-electron transistor to create a system imbedded into aerogel network Experiment with dispersing agents Concentration tuning SEM, TEM, and cryomicrotoning air Results & Discussion References Using microwave impedence spectrosopy, can characterize distribution of CNT’s in aerogel Figure below shows CNT dispersion in aerogel with very good resolution Individual nanotubes can be seen, but there is still clustering 0.1336 wt% SWCNT in 3% agarose aerogel 0.0668 wt% SWCNT in Ao, G., Khripin, C. Y., & Zheng, M. (2014). DNA-Controlled Partition of Carbon Nanotubes in Polymer Aqueous Two-Phase Systems. Journal of the American Chemical Society, 136(29), 10383-10392. Brown, S., Jesperson, T. S., & Nygard, J. (2008). A Genetic Analysis of Carbon-Nanotube- Binding Proteins. Wiley InterScience, 4(4), 416-420. Mao, B., Divoux, T., Snabre P. (2016). Normal Force Controlled Rheology Applied to Agar Gelation. University de Bordeaux. (Below percolation threshold) (Above percolation threshold) Objective Using the detergent, benzene dodecylsulfonate might not be conducive to dispersion Develop an electrically conductive CNT aerogel for long range electron transfer Integrate DNA templated devices to create 3D electronic materials Need to try other surfacants such as DNA oliqos with CNT affinity and diblock polypeptide, a good gelating domain and CNT-binding domain Acknowledgements North Carolina State University College of Engineering, NCSU Department of Materials Science & Engineering, NCSU Office of Undergraduate Research