Nanotribology, Nanomechanics and Materials Characterization Studies and Applications to Bio/nanotechnology and Biomimetics Prof. Bharat Bhushan Ohio Eminent Scholar and Howard D. Winbigler Professor and Director NLBB [email protected] Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics © B. Bhushan Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 1 Outline • Introduction Nanotribology Examples of a magnetic storage device, MEMS/NEMS and BioMEMS/BioNEMS • Measurement Techniques • Results Surface Imaging, Adhesion, Friction and Wear Adhesion, Friction and Wear of CNTs Bioadhesion Studies • Biomimetics Introduction Hierarchical Nanostructures for Superhydrophobicity, Self Cleaning and Low Adhesion • Conclusions Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 2 Introduction Nanotribology • At most interfaces of technological relevance, contact occurs at numerous asperities. It is of importance to investigate a single asperity contact in the fundamental tribological studies. Engineering Interface Tip - based microscope allows simulation of a single asperity contact • Nanotribological studies are needed To develop fundamental understanding of interfacial phenomena on a small scale To study interfacial phenomena in micro- or nanostructures and performance of ultra-thin films, e.g., in magnetic storage and MEMS/NEMS components B. Bhushan, J. Israelachvili and U. Landman, Nature 374, 607 (1995); B. Bhushan, Handbook of Micro/Nanotribology, second ed., CRC Press, 1999; B. Bhushan, Introduction to Tribology, Wiley, NY, 2002; B. Bhushan, Nanotribology and Nanomechanics – An Introduction, Springer, 2005; B. Bhushan, Wear 259, 1507 (2005); B. Bhushan, Springer Handbook of Nanotechnology, second ed., Springer, 2007. Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 3 Example of a Magnetic Storage Device Diamond like carbon overcoat 3.5 nm thick Al2O3-TiC MR type picoslider Magnetic rigid–disk drive (Bhushan, 1996) Liquid Lubricant 1- 2 nm Diamondlike carbon overcoat 3-5 nm Magnetic coating 25 –75 nm Al-Mg/10 µm Ni-P, Glass or Glass - ceramic 0.78-1.3 mm Thin–film disk B. Bhushan. Tribology and Mechanics of Magnetic Storage Devices, 2nd ed., Springer-Verlag, NY, 1996 Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 4 Examples of MEMS/NEMS and BioMEMS/NEMS springs shuttle Microgear unit can be driven at speeds up to 250,000 RPM. Various sliding comp. are shown after wear test for 600k cycles at 1.8% RH (Tanner et al., 2000) gears and pin joint Microengine driven by electrostatically-actuated comb drive Stuck comb drive Sandia Summit Technologies (www.mems.sandia.gov) Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics Microfabricated commercial MEMS components B. Bhushan. Springer Handbook of Nanotechnology, third ed., Springer-Verlag, Heidelberg, 2010 Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 6 The generating points of friction and wear due to interaction of a biomolecular layer on a synthetic microdevice with tissue (Bhushan et al., 2006) Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 7 CNT-based Nanostructures SWNT biosensor The electrical resistance of MWNT Sheet the system is sensitive to the adsorption of molecules to the nanotube/electrode. Adhesion should be strong between adsorbents and (Chen et al., 2004) SWNT. Nanotube bioforce sensor Force applied at the free end (Zhang et al., 2005) of nanotube cantilever is detected as the imbalance of Mechanical properties of current flowing through the nanotube ribbons, such as the nanotube bearing supporting elastic modulus and tensile the nanotube cantilever. strength, critically rely on the The deflection of nanotube adhesion and friction between cantilever involves inter-tube nanotubes. friction. (Roman et al., 2005) Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics Measurement Techniques Surface Force Apparatus (SFA),1968 Scanning Tunneling Microscope (STM), 1981 Atomic Force Microscope (AFM) and Friction force Microscope (FFM), 1985 B. Bhushan, J. Israelachvili and U. Landman, Nature 374, 607 (1995); B. Bhushan, Handbook of Micro/Nanotribology, second ed., CRC Press, 1999; B. Bhushan, Introduction to Tribology, Wiley, NY, 2002; B. Bhushan, Nanotribology and Nanomechanics – An Introduction, Springer, 2005; B. Bhushan, Springer Handbook of Nanotechnology, second ed., Springer, 2007. Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 9 Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 10 Results – Surface Imaging and Friction STM images of a solvent-deposited C60 film on gold coated mica B. Bhushan et al., J. Phys. D: Appl. Phys. 26, 1319 (1993) CNN Headlines News, 3/18-3/19/93, etc. Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 11 µ = 0.006 Topography and friction force maps for HOPG J. Ruan and B. Bhushan, J. Appl. Phys. 76, 8117 (1994); Y. Song and B. Bhushan, Phys. Rev. B 74, 165401 (2006) National Public Radio, 4/12/95; Business Week, 5/1/95 etc. Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 12 Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 13 Friction force map and line plots of friction force profiles for HOPG. Friction force changes discontinuously with sudden jumps. This leads to saw tooth pattern and it occurs due to atomic-scale stick-slip. Can use mechanical model proposed by Tomlinson in 1929. Equilibrium position before sliding begins Stick Slip Slip event is a AFM tip- dissipative process cantilever model Periodic interaction Sample potential surface Atomic lattice Direction of motion constant, a of sample surface The tip needs to overcome the energy barrier in order to jump from a stable equilibrium on the surface into a neighboring position. The tip remains stuck until energy stored in the spring is high enough to overcome the energy barrier. Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 14 Scale effect on friction Coefficient of Friction Nanoscale* Microscale RMS* with Si3N4 with Si3N4 Sample (nm) tip ball Si(100) 0.14 0.06 0.47 HOPG 0.09 0.006 0.1 Natural 2.3 0.05 0.2 Diamond DLC film 0.14 0.03 0.19 *Scan area = 1 µm x 1 µm Roughness, nano- and macroscale friction data of various samples J. Ruan and B. Bhushan, ASME J. Tribol. 116, 389 (1994) B. Bhushan et al., ASME J. Tribol. 126, 583 (2004) Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 15 Comparing the conditions of nanoscale and macroscale tests, there are at least four differences •Contact size in FFM is small—particles are ejected readily •Mechanical properties have size effect— properties on nanoscale are superior to the bulk properties •Applied loads in FFM are low—elastic contact regime (little plowing) •Small radius of tip results in lower friction Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 16 Custom piezo stages for high velocity sliding Ultrahigh velocity stage (upto 200 mm/s) High velocity stage (upto 10 mm/s) Schematic of experimental setup N. Tambe and B. Bhushan, J. Phys. D: Appl. Phys. 38, 764 (2005); Z. Tao and B. Bhushan, Rev. Sci. Instrum. 77, 103705 (2006) Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 17 Friction force on log scale Normal load = 100 nN 60 Si (100) Viscous shear Meniscus force dominates Friction force on linear scale Friction force on log scale (low velocity) 40 dominates 60 10 Si (100) Si (100) Atomic-scale stick 40 20 slip dominates 5 20 (nN) (nN) ee (nN)(nN) (nN) (nN) ee ee rcrc rcrc 0 rcrc 0 oo oo oo 0 f f f f nn 60 nn 10 DLC n fn f 60 DLC DLC Phase transformation/ FrictioFrictio 40 FrictioFrictio tip jump 5 FrictioFrictio 40 20 0 0 0105 2 × 105 0 1 2 3 Atomic-scale stick 10 10 10 10 20 Velocity (µm/s) Velocity (µm/s) slip dominates 0 100 102 104 106 Velocity (µm/s) Effect of velocity on friction force • Friction mechanisms vary with surfaces • At different velocity regime, different mechanisms dominate friction N. S. Tambe and B. Bhushan, Nanotechnology 15, 1561 (2004); ibid, 16, 2309 (2005); J. Phys. D: Appl. Phys. 38, 764 (2005); Appl. Phys. Lett. 86, 061906, 2005; J. Vac. Sci. Technol. A 23, 830 (2005); Ultramicroscopy 105, 238 (2005); Z. Tao and B. Bhushan, Rev. Sci Instrum. 77, 103705 (2006); J. Vac. Sci. Technol. A 25 1267(2007) Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 18 Nanofriction maps Contour map showing friction force dependence on normal load and sliding velocity. N. S. Tambe and B. Bhushan, Appl. Phys. Lett. 86, 193102 (2005); Nature Mat. In Nanozone, Feb. 17 (2005) Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 19 Nanowear map Nanowear map for DLC illustrating effect of sliding velocity and normal load. N. S. Tambe and B. Bhushan Scripta Mat. 52, 751 (2005); Tribol. Lett. 20, 83 (2005). Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics 20 Adhesion and Friction between Individual Nanotubes Experimental Schematic MWNT tip and SWNTs suspended on a micro-trench (1) Scan of MWNT tip in (2) Ramp of MWNT tip in lateral direction across vertical direction against suspended SWNT bridge suspended SWNT bridge Average diameter of suspended SWNT bridge is 1.43 nm The diameter of the MWNT tip is about 100 nm. Method (1) works for flexible MWNT tip while method (2) is suitable for stiff MWNT tip B. Bhushan, X. Ling, A. Jungen, C. Hierold, Phys. Rev. B, 2008 Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics Scan of MWNT tip in lateral direction across suspended SWNT bridge (A) (B) (C) Cantilever tapping amplitude 21 nm ABC A) Nanotubes