Laure Fabié, Hugo Durou, Thierry Ondarçuhu Nanosciences Group, CEMES CNRS Toulouse (France)

Transcription

1 Nanodroplet deposition and manipulation with an AFM tip Laure Fabié, Hugo Durou, Thierry Ondarçuhu Nanosciences Group, CEMES CNRS Toulouse (France)

2 Direct deposition methods Liquid lithography Pin and Ring method (DNA chips) Inck jet De Gan et al., Adv Mat 2004 ~ 200 µm 10 µm + flexibility -- Ø ~ 5 to 200 µm Pins Belaubre et al., APL 2003 Few µm Dip pen lithography + Ø ~ 10 nm Piner et al., Science limited in terms of transferrable molecules -- no reservoir 2

3 Direct deposition methods Liquid lithography Pin and Ring method (DNA chips) Inck jet De Gan et al., Adv Mat 2004 ~ 200 µm 10 µm + flexibility -- Ø ~ 5 to 200 µm Pins Belaubre et al., APL 2003 Few µm Dip pen lithography + Ø ~ 10 nm Piner et al., Science limited in terms of transferrable molecules -- no reservoir 3

4 NADIS : Liquid NAnoDISpensing Meister et al, Appl. Phys. Lett A.Fang, E. Dujardin, T.Ondarçuhu, NanoLett

5 Tip fabrication Channel milling by FIB Standard AFM tip: pyramidal and gold coated 2 steps : (i) thinning of the tip wall from the top (ii) milling at the tip apex from the tip side (record : 35 nm) nm 35 nm 100 nm 251 nm 500 nm Surface functionnalisation Intact gold layer (thiol chemistry) 2 distinct areas : Si 3 N 4 surface for silane chemistry and gold layer for thiol treatment

6 Tip loading Deposited liquid Glycerol or glycerol-water mixture (dilution max 6:4) Solutions of molecules, proteins, nanoparticles Loading of the reservoir Reservoir 10µm 10µm 10µm micropipette Drop deposited with a micropipette and a micromanipulator 6

7 Deposition process Deposition Nanodroplet deposition : with an AFM in force spectroscopy mode Line deposition : with an AFM in contact mode and using a nanopositioning table 7

8 Deposition process Deposition Nanodroplet deposition : with an AFM in force spectroscopy mode Line deposition : with an AFM in contact mode and using a nanopositioning table Force curve recorded during liquid transfert 8

9 Deposition process Deposition Nanodroplet deposition : with an AFM in force spectroscopy mode Line deposition : with an AFM in contact mode and using a nanopositioning table Force curve recorded during liquid transfert Deposit observation (after solvent evaporation) 9

10 Nanodroplet deposition Hydrophilic tip with an aperture of 400nm Ø ~ 75nm 1 µm Hydrophobic tip with an aperture of 35nm (treated with dodecanethiol) The influence of the different parameters is studed in : A. Fang, E. Dujardin, T.Ondarçuhu. NanoLett (2006) 1 µm 500nm 10

11 Flexibility of the method 25 nm PS NPs DsRed Proteins Ruthenium complexes 1µm 5µm 1µm 5µm 11

12 Nanopatterning conclusion 1 µl =10-6 L 1 nl =10-9 L 1 pl =10-12 L 1 fl =10-15 L 1 al =10-18 L 1 zl =10-21 L 1 mm 100 μm 10 μm 1 μm 100 nm 10 nm 12

13 Study of the deposition mechanisms Final deposits due to : flow through the channel spreading on the substrate surface 13

14 Analyse of the retraction force curves Force curve study : understanding the deposition mechanisms capillary force z F F (nn) z (nm) Small diameter Hydrophobic tip Hydrophilic tip 14

15 Modeling with Surface Evolver Energy minimization for different boundary conditions and constraints Pressure and volume Contact radii and angles surface shape Energy Pressure Volume Force 15

16 Hydrophilic NADIS tips Boundary conditions : fixed radii on the tip and on the substrate Channel of 280nm Constant pressure defined by the reservoir : Laplace pressure of a spheric drop with a 20µm radius Channel of 35nm Constant volume : No liquid flow F (nn) z (nm) 40 experiments theory F (nn) z (nm) Rsurf = 400 nm, Rtip = 250 nm Rsurf = 97 nm Rtip = 65 nm P = Pa V = 0.4 al More details on the influence of the different parameters on the force curve in : L. Fabie, H. Durou, T.Ondarçuhu. Langmuir (2010) experiments theory 16

17 Lines deposition NADIS tip is moved at constant velocity while maintaining contact onto the surface thanks to a nanopositioning table incorporated to the AFM Velocity increasing Phase image for a better contrast 17

18 Spreading dynamics Channel of 220nm Channel of 500nm Channel of 760nm Channel of 220nm Channel of 500nm Channel of 760nm Different from diffusive law (Dip pen) in t ½ J. Jang et al. J. Chem. Phys. (2001) t=w/v 18

19 Spreading dynamics Classical case Cox-Voinov equation : θ 3 θ 3 m = 9 ηv γ ln L l O.V. Voinov, Fluid Dyn. (1976) RG R.G. Cox, J. Fluid. Mech. (1986) θ Spreading at constant θ 1 R 3 volume 1 10 R t L. Tanner, J. Phys. D (1979) NADIS case Avec : tanθ θ h R R 0 0 p Spreading at constant pressure h R θ R 0 h R R dr = θm + 9αα dt η α = ln γ L l 19

20 Results of the model For θ m = 0, analytical lti lsolution lti : R-R 0 = At 1/4 For θ m 0, numerical solution h R R dr = θm + 9α dt θ m =3.5 R 0 =380nm ln(l/l)=10 α=238s/m untreated tip: h=56nm Hydrophobic tip : h=42.5nm 20

21 Results of the model For θ m = 0, analytical lti lsolution lti : R-R 0 = At 1/4 For θ m 0, numerical solution h R R dr = θm + 9α dt θ m =3.5 R 0 =380nm ln(l/l)=10 α=238s/m untreated tip: h=56nm Hydrophobic tip : h=42.5nm 21

22 Conclusion Efficient method for nanopatterning Fundamental studies Study of the capillary force at the nanoscale useful for AFMimagingi Spreading dynamics at constant pressure interesting for printing techniques 22