AVS 56th International Symposium & Exhibition
    Biomaterial Interfaces Wednesday Sessions
       Session BI+AS+NS-WeA

Paper BI+AS+NS-WeA9
Development of Microresonator Arrrays for Mass and Viscoelastic Characterization of Adsorbed Molecular and Biomolecular Thin Films

Wednesday, November 11, 2009, 4:40 pm, Room K

Session: Quantitative Nanoscale Sensing at Biosurfaces and Interfaces
Presenter: D.L. Allara, Pennsylvania State University
Authors: D.L. Allara, Pennsylvania State University
S. Tadidagapa, Pennsylvania State University
P. Kao, Pennsylvania State University
Correspondent: Click to Email
A multiple pixel micromachined quartz crystal resonator array with a fundamental resonance frequency in the 60-100 MHz range has been designed, fabricated, and tested for applications to accurate mass and viscoelastic measurements of adsorbed thin molecular and biomolecular films. Operating with high Q-factors in the range of 25000–50000 and appropriately lower in liquids, the high stability and inherent low noise of the quartz crystals allow for an unprecedented resolution of one part in 10 million for density/viscosity variations. Further, multiple pixels, capable of independent functionalization with SAMs, can be tracked in parallel to give large numbers of independent measurements simultaneously. By measuring the frequency decrease at overtone frequencies it also is possible to vary the decay length of the shear wave away from the electrode and thereby identify individual variations in the density and viscosity of the local environment and accurately monitor small changes in the viscoelastic loading of adsorbed films. The performance of the resonator is illustrated with examples such as the adsorbed protein films in which the damping factor undergoes an order of magnitude change in transitioning from monolayer to multilayer adsorption. This aspect is highly desirable for accurate determination of behavior such as conformational changes.