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

Paper MN-MoA2
Optically Driven Nanomechanical Resonant Structures for Detection of Single Molecules

Monday, October 31, 2005, 2:20 pm, Room 207

Session: Materials and Processes for Bio-MEMS and Bio-NEMS
Presenter: B. Ilic, Cornell University
Authors: B. Ilic, Cornell University
Y. Yang, Cornell University
K. Aubin, Cornell University
R. Reichenbach, Cornell University
J. Huang, Cornell University
S. Krylov, Tel Aviv University, Israel
H.G. Craighead, Cornell University
Correspondent: Click to Email
Resonant nanoelectromechanical systems (NEMS) are being actively investigated as sensitive mass detectors for applications such as chemical and biological sensing. NEMS devices, made by lithographic techniques, can be formed in highly uniform arrays in a form that can be readily integrated with motion transduction and microfluidic systems. The types of materials that can be structured in this way have low mechanical losses providing a high mechanical quality factor of the oscillators and therefore well defined resonant frequencies. The very specific resonant frequencies and small mass of the oscillator allows for detection of small amounts of additional bound mass. Experimental investigations illustrate that the ability to engineer nanoscale features on the surface of NEMS devices, combined with localized chemical functionalization, allows for specificity and calibration of these devices as detectors. In our work, we have detected the binding of functionalized 1578 base pair long double-stranded disulfide modified double stranded DNA molecules to nanomechanical oscillators by measuring the resonant frequency shift due the added mass of the bound molecules. The resonant frequency of individual oscillators in an array of resonator devices was measured by thermo-optically driving the individual devices and detecting their motion by optical interference. Localized binding sites created with gold nanodots create a calibrated response with sufficient sensitivity and accuracy to count small numbers of bound molecules. The number of bound molecules on each device was quantified as proportional to the measured frequency shift with a proportionality constant determined experimentally and verified by modeling of the mechanical response of the system. For the smallest and most sensitive cantilevers the mass sensitivity was 194Hz/attogram.