Measurement sensitivity improvement in tapping-mode atomic force microscopy through bi-harmonic drive signal

• Published in: Review of scientific instruments Vol. 82; no. 10; p. 103704
• Main Authors: Loganathan, Muthukumaran, Kodandarama, Santosh R, Bristow, Douglas A
• Format: Journal Article
• Language: English
• Published: United States 01.10.2011
• ISSN: 1089-7623
• DOI: 10.1063/1.3648103

This article presents a novel method to improve the measurement sensitivity and reduce impact forces in tapping-mode atomic force microscopy by reshaping the tip trajectory. A tapping drive signal composed of two harmonics is used to generate an oscillating trajectory with a broader valley compared to the typical sinusoidal trajectory. The wide broad valley reduces the velocity of the tip in the vicinity of the sample and allots a greater portion of each period in the vicinity of the sample. Numerical simulations show that this results in decreased impact force and increased sensitivity of the cantilever oscillation to changes in tip-sample offset. Experimental results demonstrate an increase in image sharpness and decrease in tip wear using the bi-harmonic driving signal.