Micro-manipulation using combined optical tweezers and atomic force microscope

Hullas Sehgal, Tathagata De, Saju Nettikadan, murti v salapaka

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations


In this paper, we report a novel approach to functionalize the tip of a micro-cantilever by selectively positioning a functionalized polystyrene bead using optical tweezers as a lever arm. We present a design that consists of an Atomic Force Microscope (AFM) combined with an optical tweezers setup to study specific interactions between complementary protein molecules. A BSA protein coated polystyrene bead, held stationary in an optical trap, is chemically grafted to AFM cantliever tip functionalized by the complementary protein- anti BSA. This arrangement also provides a flexible means of reversibly and irreversibly fusing polystyrene beads thermally at desired specified locations on the micro-cantilever, by heating the silicon tip with the focused laser beam of the optical tweezers. We use optical tweezers as a micro-manipulation tool for grafting pre-specified number of beads to cantilever in a controlled fashion as against the other widely used methods where an aggregate of molecules are chemically attached. Further, we study the changes in cantilever's resonant frequency and find it in good agreement with the expected change due to the additional bead mass. This study opens up opportunities in the area of biosensors by providing a method to standardize the calibration of chemically modified cantilevers.

Original languageEnglish (US)
Title of host publicationOptical Trapping and Optical Micromanipulation IV
StatePublished - Dec 1 2007
Externally publishedYes
EventOptical Trapping and Optical Micromanipulation IV - San Diego, CA, United States
Duration: Aug 26 2007Aug 29 2007

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


OtherOptical Trapping and Optical Micromanipulation IV
Country/TerritoryUnited States
CitySan Diego, CA


  • Anti BSA
  • Atomic force microscope
  • BSA
  • Micro-cantilever
  • Optical tweezers


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