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PeakForce Tapping - How AFM Should Be

Force control is central to successful imaging. In PeakForce Tapping®, the probe periodically taps the sample and the pN-level interaction force is measured directly by the deflection of the cantilever. Through superior force control, the feedback loop keeps the peak force constant, down to 10 pN, in both air and fluid, which is significantly lower than is typically used with other modes, such as TappingMode™ (~1 nN). And while the force exerted in TappingMode is a nonlinear function of multiple parameters, it is specified simply and directly with the setpoint in PeakForce Tapping.

In addition to material research, PeakForce Tapping is ideal for measurement of biological samples due to its unprecedented low imaging forces. It overcomes the many limitations of TappingMode operation in fluid, such as the need to constantly tune the cantilever. Routine measurements of live-cell mechanical properties are now available with PeakForce Tapping technology.

The ability to work routinely at low pN forces maintains tip shape and sample integrity, leading to consistently accurate and high-resolution measurements of even the smallest biological structures, such as double helix DNA.

By detecting the peak force instead of an amplitude, PeakForce Tapping is able to provide much more accurate metrology than Tapping Mode. Specifically, peak force detection eliminates air damping artifacts that hamper accurate tracking with Tapping Mode in any trench or pit structure. The same effect leads to lower tip wear in roughness measurements. PeakForce Tapping also eliminates cantilever tuning, setpoint tuning, gain tuning, and setpoint drift, enabling more reproducible dimensional and roughness measurements in industrial environments.

Bruker continues to demonstrate its leadership in AFM technology development with PeakForce Tapping, built on the foundation of five separate patents. This has led to over 1,000 peer-reviewed publications in the first five years since its release, generating nearly 3000 citations. This adoption rate has surpassed even that of TappingMode. By now, even individual PeakForce Tapping derivatives such as PeakForce TUNA have enabled hundreds of publications.

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