Biswas, S.

Fuchs, H.

Hirtz, M.

Lenhert, S.

KITopen

KIT – University of the State of Baden-Württemberg and National Large-scale Research Center of the Helmholtz Association INSTITUTE OF NANOTECHNOLOGY www.kit.edu  S. Biswas*, M. Hirtz*,**, S. Lenhert*** and H. Fuchs*,** Measurement of INK Viscosity using AFM cantilever *** Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370, USA  *Institut für NanoTechnologie, Forschungszentrum Karlsruhe GmbH, D-76021 Karlsruhe, Germany ** Physikalisches Institut and Center for Nanotechnology (CeNTech), Westfälische Wilhelms-Universität, 48149 Münster, Germany  Institute of Nanotechnology 2 25.09.2009 Motivation of the work  Nanotech Conference & Expo 2010 23. 6.2010  The Dip-Pen Nanolithography (DPN) process uses a chemically coated scanning probe tip (the “pen”) to directly deposit a material (“ink”) with nanometer precision onto a substrate.    Several experimental parameters have been observed to influence the ink transport in DPN – relative humidity, temperature, viscosity and density of the ink are the two important parameters which play a crucial role in ink transport in DPN.   It is necessary to understand and control these parameters in order to optimize DPN processes for a particular application.    It is difficult to measure the viscosity of this ink using standard processes of measuring viscosity because the DOPC is not dissolved into some organic solution while writing.  Institute of Nanotechnology 3 25.09.2009 Nanotech Conference & Expo 2010 23. 6.2010 Previous work 1) “Measurement of solution viscosity by atomic force microscopy”, REVIEW OF SCIENTIFIC INSTRUMENTS, VOLUME 72, NUMBER 6 JUNE 2001 2) “Detection of microviscosity by using uncalibrated atomic force microscopy Cantilevers”, APPLIED PHYSICS LETTERS 93, 124102, 2008 Institute of Nanotechnology 4 25.09.2009 Relation between the Resonance frequency and the Viscosity of the medium K = a constant for a given cantilever = viscosity of the medium  = density of the medium k= spring constant of the cantilever m*= mass of the cantilever Ref.:  G. Chen, R. Warmack, T. Thundat, and D. P. Allison, Rev. Sci. Instrum., 65, 2532,  (1994). Nanotech Conference & Expo 2010 23. 6.2010 Institute of Nanotechnology 5 25.09.2009 Specification of the cantilever Tip Specifications  Material: Silicon Shape: Pyramidal Height (µm): 14-16 Aspect Ratio: 1.5-3.0 ROC* (nm): < 10 nm Coating: None Cantilever Specifications  Material: Silicon Shape: Rectangular Nanotech Conference & Expo 2010 23.06.2010 Ref. http://www.appnano.com Institute of Nanotechnology 6 25.09.2009 Nanotech Conference & Expo 2010 23. 6.2010 Resonance frequency of the cantilever in air 100.0 200.0 300.0 400.0 500.0-2500-2000-1500-1000-5000Z error (in mV)Resonance Frequency (KHz)285.0 290.0 295.0 300.0 305.0-2500-2000-1500-1000-50005001000Z error (in mV)Resonance Frequency (KHz)T = 210C ± 20C RH = 40.8 % ± 2% Optical microscopic image of the  cantilever tip dipped in the micro  wells containing DOPC ink. Institute of Nanotechnology 7 25.09.2009 Resonance frequency of the cantilever in water T = 210C ± 20C RH = 40.8 % ± 2% K = 590.741 m4s1/2/kg2  = 1.002X10-3  N.s/m2   = 998.2 kg/m3 Nanotech Conference & Expo 2010 23.06. 10 175.0 180.0 185.0 190.0 195.0 200.0 205.0 210.0750.0800.0850.0900.0950.0Z error (mV)Frequency (KHz) Lorentzian fitInstitute of Nanotechnology 8 25.09.2009 Resonance frequency of the cantilever in DOPC 110.0 115.0 120.0 125.0 130.0678.0679.0680.0681.0682.0 Lorentzian fitZ error (mV) Resonance Frequency (KHz)100.0 200.0 300.0 400.0 500.0752.0753.0754.0755.0756.0757.0Z error (mV) Resonance Frequency (KHz)Drastic decrease in S/N ratio  T = 210C ± 20C RH = 40.8 % ± 2% Nanotech Conference & Expo 2010 23.06. 10  = 1.58 kg2/m4.s   Institute of Nanotechnology 9 25.09.2009 100.0 150.0 200.0 250.0 300.0-556.0-554.0-552.0-550.0-548.0-546.0Z error (mV) (Normalized)Frequency (KHz) In air In water In DOPCNanotech Conference & Expo 2010 23.06. 10 Comparison between the resonance frequencies in different medium Viscosity Increasing Institute of Nanotechnology 10 25.09.2009 Nanotech Conference & Expo 2010 23.06. 10 Different cantilever Ref. http://www.appnano.com Institute of Nanotechnology 11 25.09.2009 Nanotech Conference & Expo 2010 23.06. 10 50.0 100.0 150.0 200.0-540.0-530.0-520.0-510.0-500.0Z Error (mV) (Normalized)Frequency (KHz) In Air In Water In DOPC = 1.75 kg2/m4.s  Institute of Nanotechnology 12 25.09.2009 18 20 22 24 26 28 30 32 34 36 38 400.500.520.540.560.580.600.62Dynamic Viscosity (X10-3 Pa.S)Temperature (0C)Nanotech Conference & Expo 2010 23.06. 10 Variation of the Viscosity of the solution with temperature  = 1.460 gm/cm3 , at 240C 10 mg/ml 1, 2-Dioleoyl-sn-Glycero-3-phosphocholine (DOPC) in CHCl3 Institute of Nanotechnology 13 25.09.2009 Nanotech Conference & Expo 2010 23.06. 10 Effect of Relative Humidity 50.0 100.0 150.0 200.0 250.0 300.0-550.0-500.0-450.0-400.0Z Error (mV)Frequency (KHz) RH 10% RH 25% RH 40% RH 55% RH 75%100.0 110.0 120.0 130.0 140.0 150.0-550.0-500.0-450.0-400.0Z Error (mV)Frequency (KHz) RH 10% RH 25% RH 40% RH 55% RH 75%10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0123.0123.5124.0124.5125.0Resonance Frequency (KHz)Relative Humidity (RH%) Raw data Fitted dataInstitute of Nanotechnology 14 25.09.2009 Nanotech Conference & Expo 2010 23.06. 10 Effect of Temparature 50.0 100.0 150.0 200.0 250.0 300.0-575.0-550.0-525.0-500.0-475.0-450.0-425.0Z Error (mV)Frequency (KHz) Temp 200C Temp 250C Temp 300C Temp 340C Temp 380C100.0 110.0 120.0 130.0 140.0 150.0-575.0-550.0-525.0-500.0-475.0-450.0-425.0Z Error (mV)Frequency (KHz) Temp 200C Temp 250C Temp 300C Temp 340C Temp 380C20.0 24.0 28.0 32.0 36.0 40.0122.0122.5123.0123.5124.0Resonance Frequency (KHz)Temperature (0C) Raw Data Fitted dataInstitute of Nanotechnology 15 25.09.2009 Nanotech Conference & Expo 2010 23.06. 10 100.0 200.0 300.0 400.0 500.0-560.0-555.0-550.0-545.0-540.0-535.0Z Error (mV)Frequency (KHz) 1m down 2m down 6m down 12m down 14m downHeight dependence Institute of Nanotechnology 16 25.09.2009 Nanotech Conference & Expo 2010 23.06. 10 Conclusions and future scope of the work  The viscosity of inks used for DPN can be determined from the shift in resonance frequency of a cantilever vibrating in the ink as compared to that in air.    This method for monitoring viscosity is of relevance to all biorheologic and microfluidic applications where functionalized cantilevers have to be used.   It is a simple, yet reliable nondestructive procedure.    The effect of RH and temperature on the viscosity of the ink has been studied using the same method.    This technique will be used to screen broader range of different inks and ink mixtures to understand the influence of admixing (e.g. cholesterol in DOPC) on the viscosity. Institute of Nanotechnology 17 25.09.2009 Nanotech Conference & Expo 2010 23.06. 10 Institute of Nanotechnology 18 25.09.2009  Average of 5 measurements, sd <2%  The diameter of the micro wells where the tip of the cantilever has been dipped is 20 μm and the depth is 85 μm.  Sample volumes were ~ 0.03 nl.  The ink reservoir is large enough for convenient handling with pipettes and is  connected to the actual micro wells for dipping the tips via micro channels       (typical width ~ 6 μm). 23.06.2010 Nanotech Conference & Expo 2010 

Measurement of DPN-ink viscosity using an AFM cantilever

https://publikationen.bibliothek.kit.edu/170080871/3815757

Measurement of DPN-ink viscosity using an AFM cantilever

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