Microfluidic packaging of suspended microchannel resonators for biomolecular detection

Microfabricated transducers enable the label-free detection of biomolecules in nanoliter size samples. We have recently developed a new resonant micromechanical mass sensor that is exceptionally well suited for the detection of biomolecular interactions in a microfluidic framework. Our approach completely eliminates viscous damping by confining the fluid to the inside of a hollow resonator of less than 0.1 nL volume. However, previously we had not been able to integrate all device components and the connecting fluidics in a single package. In this paper, we present for the first time a complete chip-level package that enables efficient fluid delivery and, at the same time, provides integrated electrical contacts to actuate the resonator electrostatically. Combining these components required the development of a new packaging process: thin gaskets of poly(dimethylsiloxane) (PDMS) are micromolded and then bonded in selected areas to a metallized and patterned carrier substrate. While the process flow was specifically developed for the resonant sensor described below, the result is a general technique that can greatly simplify the packaging of many other biomedical devices using microfluidics.