Adhesion force sensed using tips on microcantilevers via an optical lever requires care to ensure that the tip alone contacts the liquid; is sensitive to high degrees of measurement error from departure from the laser spot; requires specialized optics and careful arrangement to produce a small laser probing spot; and limits the distance between cantilever and photodiode for increased force sensitivity. An alternative scheme, using microimaging electronic speckle pattern interferometry to monitor the deformation of a tipless microcantilever, necessitates that the beam be rigid enough to be independent of the drop location; is not amenable to very low adhesion force measure ment; and requires more complicated instrumentation. All these limitations can be effectively circumvented by a variable sensitivity scheme described here that harnesses the geometric properties of a dangling cantilever operating as an optical lever.
© 2011 Optical Society of America
Original Manuscript: June 17, 2010
Revised Manuscript: September 20, 2010
Manuscript Accepted: October 2, 2010
Published: January 10, 2011
Yohannes Panduputra, Tuck Wah Ng, Adrian Neild, and William Yeong Liang Ling, "Adhesion force studies using a dangling optical lever with variable sensitivity," Opt. Lett. 36, 175-177 (2011)