Intellectual Merits: The objective of this research is to determine the feasibility of dynamic modulation of the impedance of a microfluidic channel modified by electrical-field-effect polymer brushes. The approach is to nanofabricate field or chemical responsive polymer brushes onto the surface of microfluidic channels, investigate the electrical-field-effect I/V characteristics of the polymer brush-modified microchannels and develop dynamic modulation/multiplexing techniques for high speed biosensor applications. The use of dynamic channel modulation and signal multiplexing makes it possible to acquire data from a large number of channels without individual detection electronics for each channel. It is particularly important for high speed bioassays. Successful delivery of the proposed work will lead to high-throughput micro-Coulter counting devices for rapid bioassay of micro/nano scale bioparticles. It will also facilitate the development of active nano devices that require flow control in smart nanochannels, such as molecular syringes for controlled drug delivery. Broader Impacts: The concept, activities, and results from this project will be incorporated into undergraduate and graduate courses. Biosensor senior design projects for undergraduate students in mechanical engineering and chemistry will be offered. Undergraduate researchers will be recruited to conduct research in this project, with an emphasis on underrepresented minorities and women. Through the summer and Saturday workshops funded by an NSF education grant, middle school students, including those with special learning disabilities and their teachers will be exposed to the cutting edge nanotechnology and biosensors developed in this project. The middle school students will be encouraged to explore science and engineering as a future career choice.