Photothermal excitation of microcantilevers in liquids

High efficiency laser photothermal excitation of microcantilever vibrations in air and liquids.

Photothermal excitation is a promising means of actuating microscale structures. It is gaining increased interest for its capability to excite atomic force microscopy (AFM) microcantilevers with wide frequency bandwidth in liquid environments yielding clean resonance peaks without spurious resonances. These capabilities are particularly relevant for high speed and high resolution, quantitative ...

Photothermal excitation for improved cantilever drive performance in tapping mode atomic force microscopy

Photothermal excitation is an alternative cantilever drive mechanism for tapping mode atomic force microscopy. It uses a power-modulated laser focused on the cantilever to directly drive its oscillation, producing cantilever tunes that match the thermal response almost perfectly. This enables quantitatively accurate AFM imaging and viscoelastic nanomechanical mapping in all environments. In add...

Quantitative force and dissipation measurements in liquids using piezo-excited atomic force microscopy: a unifying theory.

The use of a piezoelectric element (acoustic excitation) to vibrate the base of microcantilevers is a popular method for dynamic atomic force microscopy. In air or vacuum, the base motion is so small (relative to tip motion) that it can be neglected. However, in liquid environments the base motion can be large and cannot be neglected. Yet it cannot be directly observed in most AFMs. Therefore, ...

Comparative dynamics of magnetically, acoustically, and Brownian motion driven microcantilevers in liquids

Origins of phase contrast in the atomic force microscope in liquids.

We study the physical origins of phase contrast in dynamic atomic force microscopy (dAFM) in liquids where low-stiffness microcantilever probes are often used for nanoscale imaging of soft biological samples with gentle forces. Under these conditions, we show that the phase contrast derives primarily from a unique energy flow channel that opens up in liquids due to the momentary excitation of h...