Carlos Andrés Jarro Dr. J. Todd Hastings Improvement on Pattern Quality Made by Negative-tone Silver Patterning using AFM and Laser-induced Deposition from Liquids Carlos Andrés Jarro Dr. J. Todd Hastings I HAVE BEEN WORKING IN DR HASTINGS LAB FOR 3 YEARS ON SILVER NANOPARTICLES FORMATION, DEPOSITION, AND APPLICATIONS.

Fabrication of silver nanoparticles is not new Fabrication of silver nanoparticles is not new. The silver institute says that the first published paper on fabrication of silver nanoparticles in solution dates from 1889. That is 124 years worth of research and we still try to find ways to form, shape, and control the synthesis of silver nanoparticles today.

Previous Work In Solution On Substrates Chemically synthesized Photo synthesized On Substrates Surface-Enhanced Raman Spectroscopy (SERS) Antibacterial surfaces Patterning 100nm Uncoated Coated Lv, H. Liu, Z. wang, L. Hao, J. Liu, Y. Wang, G. Du, D. Liu, J. Zhan and J. Wang, Polymers for Advanced Technologies, n/a (2008). Massive amount of research in formation of silver nanoparticles, most of them in solution; using different chemistry (Capping agents, reducing agents, molecules containing silver) and different temperatures. Change high temperatures for the use of light. Many researchers form silver NP in solution and then deposit them on substrates but others have formed the NP directly on the substrate. Mostly for SERS applications, but also antibacterial surfaces, film deposit or patterning. Y. Sun and Y. Xia, Science 298, 2176 (2002). 200nm H. Jia, W. Xu, J. An, D. Li and B. Zhao, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 64, 956 (2006). H. Lu, H. Zhang, X. Yu, S. Zeng, K.-T. Yong and H.- P. Ho, Plasmonics 7, 167 (2011). Y. Wan, Z. Guo, X. Jiang, K. Fang, X. Lu, Y. Zhang and N. Gu, Journal of colloid and interface science 394, 263 (2013). B. Xu, Z. Ma, L. Wang, R. Zhang, L. Niu, Z. Y. Yang, Y. Zhang, W. Zheng, B. Zhao, Y. Xu, Q. Chen, H. Xia and H. Sun, Lab on a Chip 11, 3347 (2011). A. Lachish-Zalait, D. Zbaida, E. Klein and M. Elbaum, Advanced Functional Materials 11, 218 (2001).

Agenda Previous Work Hypothesis Experimental Setup Results and Discussion Conclusions Future Work & Applications

Previous Work -Experimental Setup AgNO3 + Na-citrate O-ring Glass slide 532 nm Continuous Wave Laser

Previous Work -Silver deposition hv + + e- Acetone-1,3-dicarboxylate Carbon dioxide 1 mM Sodium Citrate + + Ag 1 mM Silver nitrate

Agenda Previous Work  Hypothesis Experimental Setup Results and Discussion Conclusions Future Work & Applications

Hypothesis -AFM tip introduction Illuminated sharp tip Plasmonic enhancement Patterns of silver ONLY where the tip scans What if we can find an intensity value at which there is no deposition on the substrate but due to the plasmonic enhancement at the tip’s apex there will be deposition below the tip’s location I. Notingher and A. Elfick, J. Phys. Chem. B 109, 15699 (2005).

Agenda Previous Work  Hypothesis  Experimental Setup Results and Discussion Conclusions Future Work & Applications

Experimental Setup AFM gold coated tip AgNO3 + Na-citrate O-ring Glass slide 532 nm Continuous Wave Laser

Agenda Previous Work  Hypothesis  Experimental Setup  Results and Discussion Conclusions Future Work & Applications

Results and Discussion Intensity Scan speed Illumination times Deposition everywhere EXCEPT where the tip scans Further deposition suppressed where tip scans

Results and Discussion -Negative tone patterning. What shapes?

Results and Discussion -Negative tone patterning. How small? 200 nm-250 nm

Results and Discussion Reduce nanoparticles’ size Shorter illumination times Improved precursor concentrations Increase deposition density Longer illumination times Coat the glass slide

Results and Discussion Silver Nitrate concentrations 0.1 mM 1 mM 10 mM Sodium Citrate Concentrations No deposition Observed Reacted without illumination 36 nm diameter 0.8% coverage 29 nm diameter 6.7% coverage 43 nm diameter 2.6% coverage 66 nm diameter 13.7% coverage 29 nm diameter 7.1% coverage 29 nm diameter 7.1% coverage 56 nm diameter 3.4% coverage 85 nm diameter 15.3% coverage

Results and Discussion Reduce nanoparticles’ size Shorter illumination times Improved precursor concentrations Increase deposition density Longer illumination times Coat the glass slide

Results and Discussion -Glass coating with APTES AminoPropylTriEthoxySilane APTES is a silane with one amine group and three methyl groups. In water it reacts replacing the methyl groups with hydroxyl groups, forming ethanol, and adding a hydrogen nucleus to the amine group. This is called a protonized APTES. Negatively charged citrate adsorbs to the silver nanoparticles coating them with a negative charge and hence being attracted to the APTES coated slide.

Results and Discussion -Glass coating with APTES Comparison of coated and uncoated sample Without APTES With APTES Without APTES: 34% area coverage in the densest region. With APTES: Approximately 100% area coverage.

Results and Discussion -Patterning

Agenda Previous Work  Hypothesis  Experimental Setup  Results and Discussion  Conclusions Future Work & Applications

Conclusions Developed a technique that allows direct deposition and patterning of silver in one step. Reduced the patterns width by optimizing the precursor solution to obtain smaller nanoparticles. Improved the coverage of the films by coating the glass substrate with APTES

Agenda Previous Work  Hypothesis  Experimental Setup  Results and Discussion  Conclusions  Future Work & Applications

Future Work & Applications Improve the resolution of the technique to form even narrower patterns Enhanced tip positioning control Optimize illumination and AFM parameters (illumination time, scan speed, number of scans) Continue the refinement of the formation of silver to obtain even smaller nanoparticles Applications in rapid prototyping Applications in plasmonic sensing

Thank you CMMI-0800658 and ECCS-074 7810