Temperature controlled AFM

Enders O, Ngezahayo A, Wiechmann M, Leistrm F, Kolb HA (2004) Structural calorimetry of main transition of supported DMPC bilayers by temperature-controlled AFM. Biophys J... 

Whereas the first experiments on structmral forces in liquid crystals were performed using a Surface Force Apparatus (SFA, discussed later on in part 3 of this chapter), a temperature controlled AFM was used later [4] to measure the forces between the AFM probe and the surface, mediated by a liquid crystal in between. Compared to other methods, using an AFM for measuring surface forces has some advantages and also some drawbacks. The most important advantage is, that the temperature of the sample can be controlled in a simple way to better than 0.01 K. Furthermore, the sample is not in direct contact with large mechanical parts like in the case of a SFA, and only a small amount of liquid crystal is needed for the experiment. The drawback of the AFM is, that the separation between surfaces is not measured directly... 

Fig.l a Sketch of the temperature-controlled AFM setup. The entire AFM was placed in a temperature controlled box to keep the top part of the sample in the isotropic phase. This permits to determine the deflection of the cantilever from the reflection of a laser beam. The temperature of liquid crystal close to the substrate was controlled using a second heater, placed on top of the piezo scanner. To protect the piezo from overheating the AFM scanner was cooled, b Scanning electron microscope image of a silica sphere of radius 3.3 xm, glued to the cantilever with a resin. The microsphere is attached to the cantilever using a 3D micropositioning system under an optical microscope... 

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