AVS 52nd International Symposium
    MEMS and NEMS Monday Sessions
       Session MN-MoA

Paper MN-MoA5
Toward a Chitosan-Based Micromechanical Biosensor

Monday, October 31, 2005, 3:20 pm, Room 207

Session: Materials and Processes for Bio-MEMS and Bio-NEMS
Presenter: S.T. Koev, University of Maryland, College Park
Authors: S.T. Koev, University of Maryland, College Park
M.A. Powers, University of Maryland, College Park
H. Yi, University of Maryland, College Park
R. Ghodssi, University of Maryland, College Park
Correspondent: Click to Email
In this work, the electrically deposited polysaccharide chitosan is used to biofunctionalize a microcantilever biosensor which detects the presence of target molecules on the chitosan as a shift in the resonant frequency of the cantilever. We have previously demonstrated the use of chitosan for spatially selective assembly of various biomolecules and now extend its functionality to a micromechanical sensor. Chitosan offers significant advantages over other materials commonly used for immobilization of biomolecules. The electrodeposition of chitosan would allow facile patterning of different probe biomolecules in sensor arrays. Additionally, chitosan's surface roughness, which can be controlled by the deposition conditions, leads to a large effective surface area for target molecule coupling. The microcantilever consists of layers of chitosan (100 nm), Cr/Au (110 nm), and Si@sub3@N@sub4@ (500 nm) fabricated on a Si substrate. The Au layer is used both for chitosan deposition and electrostatic actuation. The cantilever's resonant frequency is measured by actuating it at different frequencies and recording the amplitude with an optical profilometer in dynamic mode. Amine terminated ssDNA probe molecules are coupled to the chitosan amine groups using glutaraldehyde as a crosslinker and are hybridized with their complements. Resonant frequency measurements are performed after each of the following steps: chitosan deposition, addition of probe DNA, and addition of complementary target DNA. The data are analyzed to extract the surface mass density of DNA immobilized on the chitosan. The detailed fabrication, characterization, and measurement results will be presented.