Measurement of nonlinear piezoelectric coefficients using a micromechanical resonator

We describe and demonstrate a method by which the nonlinear piezoelectric properties of a piezoelectric material may be measured by detecting the force that it applies on a suspended micromechanical resonator at one of its mechanical resonance frequencies. Resonators are used in countless applications; this method could provide a means for better-characterizing material behaviors within real MEMS devices. Further, special devices can be designed to probe this nonlinear behavior at specific frequencies with enhanced signal sizes. The resonators used for this experiment are actuated using a 1-$\mu$m-thick layer of aluminum nitride. When driven at large amplitudes, the piezoelectric layer generates harmonics, which are measurable in the response of the resonator. In this experiment, we measured the second-order piezoelectric coefficient of aluminum nitride to be $-(23.1\pm14.1)\times10^{-22}\ \mathrm{m/V^2}$.Comment: 5 pages, 3 figures, preprin

Measurement of nonlinear piezoelectric coefficients using a micromechanical resonator

We describe and demonstrate a method by which the nonlinear piezoelectric properties of a piezoelectric material may be measured by detecting the force that it applies on a suspended micromechanical resonator at one of its mechanical resonance frequencies. Resonators are used in countless applications; this method could provide a means for better-characterizing material behaviors within real MEMS devices. Further, special devices can be designed to probe this nonlinear behavior at specific frequencies with enhanced signal sizes. The resonators used for this experiment are actuated using a 1-μm-thick layer of aluminum nitride. When driven at large amplitudes, the piezoelectric layer generates harmonics, which are measurable in the response of the resonator. In this experiment, we measured the second-order piezoelectric coefficient of aluminum nitride to be −(23.1±14.1)×10^−22m/V^2.Published versio

Wireless actuation of bulk acoustic modes in micromechanical resonators

We report wireless actuation of a Lamb wave micromechanical resonator from a distance of over 1 m with an efficiency of over 15%. Wireless actuation of conventional micromechanical resonators can have broad impact in a number of applications from wireless communication and implantable biomedical devices to distributed sensor networks.Financial support from FemtoDx is acknowledged. (FemtoDx)http://nano.bu.edu/Papers_files/Wireless-APL-4961247.pdfPublished versio

Wireless actuation of micromechanical resonators

The wireless transfer of power is of fundamental and technical interest, with applications ranging from the remote operation of consumer electronics and implanted biomedical devices and sensors to the actuation of devices for which hard-wired power sources are neither desirable nor practical. In particular, biomedical devices that are implanted in the body or brain require small-footprint power receiving elements for wireless charging, which can be accomplished by micromechanical resonators. Moreover, for fundamental experiments, the ultralow-power wireless operation of micromechanical resonators in the microwave range can enable the performance of low-temperature studies of mechanical systems in the quantum regime, where the heat carried by the electrical wires in standard actuation techniques is detrimental to maintaining the resonator in a quantum state. Here we demonstrate the successful actuation of micron-sized silicon-based piezoelectric resonators with resonance frequencies ranging from 36 to 120 MHz at power levels of nanowatts and distances of ~3 feet, including comprehensive polarization, distance and power dependence measurements. Our unprecedented demonstration of the wireless actuation of micromechanical resonators via electric-field coupling down to nanowatt levels may enable a multitude of applications that require the wireless control of sensors and actuators based on micromechanical resonators, which was inaccessible until now.http://nano.bu.edu/Papers_files/micronano201636.pdfPublished versio

Channel-Width Dependent Enhancement in Nanoscale Field Effect Transistor

We report the observation of channel-width dependent enhancement in nanoscale field effect transistors containing lithographically-patterned silicon nanowires as the conduction channel. These devices behave as conventional metal-oxide-semiconductor field-effect transistors in reverse source drain bias. Reduction of nanowire width below 200 nm leads to dramatic change in the threshold voltage. Due to increased surface-to-volume ratio, these devices show higher transconductance per unit width at smaller width. Our devices with nanoscale channel width demonstrate extreme sensitivity to surface field profile, and therefore can be used as logic elements in computation and as ultrasensitive sensors of surface-charge in chemical and biological species.Comment: 5 pages, 4 figures, two-column format. Related papers can be found at http://nano.bu.ed

Phase cascade bridge rectifier array in a 2-D lattice

We report on a novel rectification phenomenon in a 2-D lattice network consisting of N×N sites with diode and AC source elements with controllable phases. A phase cascade configuration is described in which the current ripple in a load resistor goes to zero in the large N limit, enhancing the rectification efficiency without requiring any external capacitor or inductor based filters. The integrated modular configuration is qualitatively different from conventional rectenna arrays in which the source, rectifier and filter systems are physically disjoint. Exact analytical results derived using idealized diodes are compared to a realistic simulation of commercially available diodes. Our results on nonlinear networks of source-rectifier arrays are potentially of interest to a fast evolving field of distributed power networks