How to get Force, Force Gradient and Damping

How to get Force, Force Gradient and Damping
with a single scan and how to image in the
attractive regime in any environment.
L. Costa1,3, M. S. Rodrigues1,4, J. Chevrier2,3,F. Comin1
ESRF. 6 Rue Jules Horowitz, BP 220, 38043 Grenoble, France
2
Institut Néel, 25 rue des Martyrs, BP 166, 38042 Grenoble, France
3
Université Joseph Fourier, 38041 Grenoble, France
4
CFMC-FCUL University Lisboa, 1749-016 Lisboa, Portugal
1
We developed a new Atomic Force Microscope that we called “Force Feedback Microscope” [1][5].
Avoiding the cantilever “Snap on” the surface, it gives the possibility to measure independently and simultaneously the Force,
the Force gradient and the Damping between the AFM probe and the sample in both the attractive and repulsive regimes.
It can work in air and liquid environments and can detect forces below the picoNewton limit.
Non Contact images of biological samples in solutions can be acquired.
Their visco-elastic properties can be investigated simultaneously to the acquisition of the topography in the repulsive regime.
■ WHY ANOTHER AFM ? -
“When you have a new idea, few people
trust you before it works”
• Because the “Jump to contact” limits the non-contact imaging.
• Because, despite the many efforts that have been made to extend the FM-AFM to the
liquid environment [2], the huge decrease of the Q-factor and the presence of thermal
noise at the cantilever resonance still limits the AFM sensitivity in such ambient.
■ EXPERIMENTAL SET-UP-“A direct measurement of atomic forces”
An adapted feedback control keeps the distance xt between the AFM probe and an optical
fibre constant, counteracting via an actuator every kind of force acting on the probe.
The actuator is the lever itself: displacing the base of the cantilever with a Piezoelectric
element, the counteracting force is applied to the tip.
A
• Because at present AFM cannot be applied to the observation of fine structures on living
cell membranes, as the membranes are extremely soft compared with available
cantilevers. Thus, it is necessary for AFMs to have the ability of non-contact imaging in
liquids [3].
• Because, as suggested by the emerging multi-frequency techniques, the recording of
nano-mechanical properties of biological samples while acquiring imagesgives access
to a lateral resolution below 10nm with a surprising gain in the acquisition time
compared to Force-Volume method [4].
■ NEW FORCE CURVES -
“Attractive forces are now accessible”
Mica
in deionised
water
Black – Complete force curve with the
FFM
Blue-Red – Approach-Retract force
curve including the range of force not
accessible in conventional static Mode
Green line – Tip sample distance
where jump to contact would occur in
static mode
No jump to
contact:
short - range
attractive
forces are now
accessible and
can be used as
set point to
perform
microscopy.
A
Fsample/probe
A fibered Fabry-Pérot
interferometer
measures
the instantaneous
position of the
cantilever
B
OPERATION MODE:
Ffeedback = - Fsample/probe
■ FORCE,
FORCE GRADIENT,
DAMPING simultaneously
“An oscillation small enough is imposed to
the tip around its equilibrium position”
■ NEW IMAGING
“Choose your
STRATEGIES - set-point”
SETPOINT
RECORDING
FORCE
TOPOGRAPHY
FORCE GRADIENT
DAMPING
FORCE GRADIENT
TOPOGRAPHY
FORCE
DAMPING
DAMPING
TOPOGRAPHY
FORCE
FORCE GRADIENT
LIPIDS on Mica in Solution – Image acquired at constant
repulsive Force of 50 pN
Approach – Retract in
conventional Static
Mode
The force in blue is obtained integrating the measured Stiffness
The force in red is the real time force measured
■ FFM IN THE ATTRACTIVE REGIME
Topography
Ffeedback
B
P r o t ei n
Buffer
:
s TB K
& OPT
2 0m M
N
HE P E S
5 mM
M g Cl
2
Complete characterisation
of the interaction
■ FFM IN THE
REPULSIVE
REGIME
P r o t ei n
Buffer
:
s O P TN
2 0m M
HE P E S
5 mM
M gC l
2
Topography
Max 19.9 nm
Max 0.002 N/m
Force gradient
Min -0.019 N/m
Min 0.0 nm
Force gradient
Max 0.02 N/m
Min 0.08 μKg/s
REFERENCES:
“We've learned from
experience that the truth will come out”
Richard P. Feynman 1974
Achieve chemical resolution
in air and liquid environment
during topography data
acquisition :
Non-Contact AFM.
Min 0.11 μKg/s
• Non contact AFM of living
cells
[1] M. S. Rodrigues, L. Costa, J. Chevrier and F. Comin, “Measurement of the complete force curve at the nanoscale”, arxiv, 1205:19332 (2012)
[2] T. Fukuma, K. Kobayashi, K. Matsushige and H. Yamada, "True molecular resolution in liquid by frequency-modulation atomic force
microscopy", Appl. Phys. Lett., vol. 86, 193108 (2005)
[3] T. Ando, T. Uchihashi, T. Fukuma, “High-speed atomic force microscopy for nano-visualization of dynamic biomolecular processes”,
Progress in Surface Science, vol. 83, pp.337-437 (2008)
[4] A. Raman, S. Trigueros, A. Cartagena, A. P. Z. Stevenson, M. Susilo, E. Nauman and S. Antoranz Contera, “Mapping nanomechanical properties
of live cells using multi-harmonic atomic force microscopy”, Nature Nanotech., vol. 6, pp. 809-815 (2011)
We acknowledge support from the project ANR-09-NANO-042-02 PianHo
[5] Patent B11187 (2011.) “Dispositif de mesure de force atomique”, E.S.R.F, Université Joseph Fourier
■ NEXT STEPS
Damping
Min -0.001 N/m
Max 1.13 μKg/s
Force
Force gradient Elasticity
• High speed non-contact
measurements of organic
materials, proteins, DNA,
polymers.
Max 6.19 μKg/s
Damping
Topography