Lateral Force Calibration

AFM Lateral Force Microscope Calibrator – LFMC

 

 

  • Automated and innovative Lateral Force Calibration
  • High-performance and accuracy
  • Compatibility with many AFM Systems

 

 

LFMC – Lateral force calibrator for your AFM

Atomic force microscope (AFM) has emerged as a significant tool for different fields of a research, like materials science, surface science, biology etc. It is a very high resolution type of a scanning probe microscope (SPM) with resolution up to atomic size. In this device an image is obtained by measuring forces that sample imposes on sharp tip microfabricated at the end of a small cantilever. The force deflects the cantilever and the deflection is usually measured by a precise optical system.

In the field of tribology, the Lateral Force Microscopy (LFM) mode is commonly used. It employs movement of a cantilever in the direction perpendicular to its longer axis, contrary to modes mentioned above. In this mode, the cantilever’s tip slides on a surface of a sample and torsional deflection of the cantilever is measured by a precise optical system. Usually a position sensitive diode (PSD) is applied, which can measure both, normal and torsional deflection of the cantilever. Torsional deflection is usually caused by a friction force between the tip and the sample’s surface. It should be noted that precise measurements of friction forces require an accurate value the cantilever’s torsional spring constant and the PSD sensitivity. The combination of these two parameters gives the AFM lateral force calibration constant (LFCC).

We present a simple and direct calibrator for LFCC determination which does not require the knowledge about material or geometrical parameters of the investigated cantilever. We use a microforce sensor (MFS) for direct measurement of the friction force applied by the cantilever’s tip to a flat silicon surface. Due to the third law of dynamics, the friction force of the equal value tilts the cantilever. Therefore, torsional (lateral force) signal is compared with the signal from MFS and LFCC is calculated.

Due to our new calibration technology Lateral Force Microscopy never was so accurate!

Principle of work

Basically, the AFM tip slides on the silicon surface of the MEMS force sensor beam (Fig. a). Due to the third law of dynamics, the value of force which tilts the AFM cantilever is equal to the value of force which pulls or pushes the beam. Extremely precise MEMS microforce sensor (MFS) allows to calibrate the lateral force signal with a very high accuracy. Fig. b shows  a photo of a cantilever over the MFS beam.

Patented calibration principle.

Our method is under process to obtain Europeian patent.

Experimental

We tested different types of cantilevers from very soft to ultra stiff. For the sake of presenting the advantages of our technique, three standard probes were calibrated. Furthermore, a popular calibration method - clasical wedge method and improved Wedge method proposed by Wang et al. method was applied for comparison. Calibration performed on TetraX are indenpendent from normal force and cantilever stiffness, LFCC determination error is below 3%.Our novel calibration method was published in ULTRAMICROSCOPY vol 182. and meets with positive feedback. Tetrax enables LFCC calibration for wide range of cantilevers with sustained calibration accuracy.

Publication: Read more

Specification: TetraX LFMC Compact specification   (1,07 mb)

PATEND PENDING

Index: TRI-TETRAX

Price: Contact Us