lifeScan System
DEPARTS FROM CURRENT AFM DESIGNS
EXTENDS HIGH RESOLUTION TO BIOMOLECULES
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| New Design |
New Performance |
Best Resolution |
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True digital control of the cantilever position and angle during approach
- detects molecule height with minimum cantilever deflection and compressive force
- a single, low force contact made with the molecule each pixel
- smallest diameter and other fragile tips are preserved and re-useable
Calibrated magnetic force ramp separates tip and molecule each pixel
- cantilever can be soft which reduces molecule damage
- adhesion force on withdrawal is plotted each pixel in all field sizes producing force maps at resolution comparable to topography
- can optimize the lift-off force for measured tip withdrawal
Improved accuracy of height profiles through a completely digital height correction
- measurement of the cantilever position moving to contact is carried out digitally in angstrom steps at microsecond intervals
- feedback to the specimen piezo to correct for change in molecule height is by secure digital transfer, not by differential equation and operator adjustment of gains
- digital feedback correction is intra-pixel fast, not an analog correction that is increased in responsiveness until oscillation occurs
Complete force curve available each pixel of every 256 by 256 scan to monitor approach, detect, contact, and withdrawal from molecule
- permanent output files created
- graphic display of actual detect point vs. set point to control quality of topographic data
- graphic display shows effect of chosen compressive force on the adhesion force between tip and molecule
Gaining Resolution
The smallest diameter tips, which are known to break under most operating conditions where low compressive force is not available, will yield the best resolution.
 DNA width
A simple, reliable indicator of resolution capability in biological AFM is imaging the native 2 nm width of DNA. A 1 nm diameter, single-wall carbon nanotube (SWCT) tip grown on a soft cantilever images the narrowest DNA.
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15 nm wide DNA
imaged by
13 nm diameter silicon nitride tip
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8 nm wide DNA
imaged by
6 nm diameter silicon tip
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3 nm wide DNA
imaged by
1 nm diameter SWCT tip
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