Piezoelectric resonant nanochannels

In recent years, the demand of miniaturized sensors able to operate in fluids has been steadily growing for a variety of different applications ranging from medical diagnostic to automotive and environmental monitoring. This dissertation presents the design and the experimental verification of a new class of high frequency piezoelectric aluminum nitride resonant sensors formed by laterally vibrating nanochannels, named Piezoelectric Resonant Nanochannels (PRNs), which work in fluids with reduced damping. The unique advantages of the proposed technology are discussed in this thesis and the capabilities to simultaneously solve the issues related to the transduction efficiency of nanoscale structures in liquids, and to address the reduction of viscous damping are demonstrated. PRNs with frequencies of operation ranging from 12 MHz to 1 GHz were designed, fabricated on the same die and tested achieving quality factors as high as 1700 when operated in fluids at 13 MHz. Several designs and channels widths have been designed and experimentally tested in order to find the best trade-off between sensitivity and quality factors. In this dissertation, a single transistor oscillator based on an 18 MHz piezoelectric resonant nanochannel is presented as the first demonstration of MEMS acoustic resonators with integrated nanochannels connected to a compact and portable oscillator readout despite the operation in liquids. This result represents a breakthrough for MEMS resonators operated in liquid as these devices are the first of their kind to be directly connected to a compact electronic oscillator