Liquid nanodispensing : molecules deposition and manipulation of ultrasmall droplets

CIC nanoGUNE Seminars

Thierry Ondarçuhu. Nanosciences group, CEMES-CNRS, Toulouse, France
nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
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Liquid nanodispensing : molecules deposition and manipulation of ultrasmall droplets Controlled deposition of individual molecules on a surface is an important challenge in many studies in nanosciences. We present an AFM-based method for dispensing and manipulation of liquid nanodroplets on a surface. This newly developed nanoscale dispensing system (NADIS) is based on the direct transfer of liquid from a hollow AFM tip through a small aperture at its apex to the substrate by simple contact [1]. With an ink supplied from an on-tip reservoir, we can transport droplets onto a substrate in the femtoliter to attoliter range with a high droplets density. We explored the liquid transfer mechanism from the tip to the substrate and showed that the size of dispensed droplets can be accurately and reproductively controlled by parameters such as the aperture size on the probe, the surface energy of both the tip outer wall and the sample surface [2]. By scaling down this method, we were able to deposit arrays of droplets with a diameter as small as 70 nm, which for standard dilutions contains only few molecules. Direct patterning of proteins or nanoparticles demonstrated the versatility of the method. An original deposition set-up including two AFM tips was also developed [3] in order to position the droplets on predefined structures on the surface, a crucial point for many applications. Due the small dimensions of the manipulated droplets, NADIS is also a unique technique to study wetting and capillarity at nanometer scale [4,5], a question which remains largely unanswered. References: [1] A.Meister, M. Liley, J. Brugger, R. Pugin, H. Heinzelmann, Appl. Phys. Lett. 85 (2004) 6260. [2] A.Fang, E. Dujardin, T.Ondarçuhu, NanoLett. 6 (2006) 2368. [3] T. Ondarçuhu, L. Nicu, S. Cholet, C. Bergaud, S. Gerdes, C. Joachim, Rev. Sci. Instr. 71 (2000) 2087-2093. [4] J. Arcamone, E. Dujardin, G. Rius, F. Pérez-Murano, T. Ondarçuhu, J.Phys.Chem.B 111 (2007) 13020. [5] L. Fabié, H. Durou, T. Ondarçuhu, Langmuir, 26 (2010) 1870