Thermally actuated tapping mode atomic force microscopy with polymer microcantilevers

This paper demonstrates a thermally actuated tapping mode atomic force microscopy (AFM) with a polymer cantilever. The cantilever (350x250x3 mu m(3)) is made from polyimide and includes an embedded resistive heater for thermal actuation. The oscillation of the cantilever is due to the stress gradient caused by alternating heating and cooling from the periodic ac excitation of the heater. The tip oscillation amplitude is 5-10 nm in air. The oscillation occurs at 2 omega and is a linear function of the applied voltage. The maximum oscillation amplitude is seen at 0.8 Hz with a 3dB frequency of 26 Hz. The damping of the oscillation due to tip-sample interaction is used to image the sample without any optomechanical feedback. Scans with a 200 nm tall grating indicate a resolution comparable to deflection signal from the AFM in contact mode.