A1.1 - Resonant Acoustic Profiling for Diagnostics

SENSOR+TEST Conferences 2009
2009-05-26 - 2009-05-28
Congress Center Nürnberg
Proceedings SENSOR 2009, Volume I
A1 - Microacoustic Sensors
M. Cooper - Cambridge Medical Innovations Ltd., Cambridge, Great Britain
23 - 27


Acoustic biosensors allow the label-free detection of molecules and the analysis of binding events. In general, they are based on quartz crystal resonators, in which the mode of oscillation depends on the cut and geometry of the quartz crystal. If mass is applied on to the surface of the quartz resonator, the frequency of the oscillation decreases. By measuring the change of frequency, it is possible to determme the change in mass. Measurement of mass by using quartz crystal resonators was first examined by Sauerbrey, who showed that the frequency change of the crystal resonator is a linear function of the mass per area or absolute. The advantages of acoustic sensor Systems that exploit the piezoelectric effect to measure mass binding and molecular interactions have long been discussed, with the technology proffered as an alternative to optical biosensors. The technique has also been shown to be capable of detecting subtie changes in the solution-surface interface that can be due to density-viscosity changes m the solution, viscoelastic changes in the bound interfacial material, and changes in the surface free energy. More specifically, Signal transduction via the piezoelectric mechanism operates well in complex, often optically-intractable media. We demonstrate here that with improvements to acoustic biosensor liquid handling, thermal control, surface chemistries and microfluidics, increases in sensitivity are achieved that enable both high and low molecular weight analytes to be detected. By formation of a non-planar three-dimensional matrix to which a member of a specific binding pair can be attached, an increased amount of the other member of the pair can be captured. This not only increases receptor binding capacity and sensitivity, but also has the effect of reducing the degree of non-specific binding to the surface by effectively masking the chemical and physical properties of the metallic electrode surface. The technology can thus be applied to an extremely wide range of biological and chemical entities with a molecular weight range from less than 200 Daltons through to an entire bacterium or cell.