Wireless actuation of micromechanical resonators

Abstract

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. INTRODUCTION Wireless energy transfer1 consists of energy transfer from any appropriate source to an energy-consuming device 2,3 and implanted biomedical devices and sensors 4-8 without the use of physical conductors or solid connecting wires. Predominantly, wireless energy transfer can be realized via either magnetic (B-field) or electric field (E-field) coupling between the source and receiver. Mechanisms involving the inductive coupling of magnetic fields require the short-range placement of an external (source) and an internal (receiver) coil. Mechanisms involving E-field coupling allow the source and receiver antennas to be proximately located. However, at present, they require the microfabrication of LC circuits and the incorporation of highly efficient radio frequency rectifying circuits at the receiver end.

Autoassociative Memory and Pattern Recognition in Micromechanical Oscillator Network

“…Recent experimental work has achieved synchronization between seven resonator elements via electromagnetic radiation 36 , though external fields cannot easily provide the sort of nonuniform coupling required for pattern storage. Recently, micromechanical oscillators have been wirelessly excited by patch antenna on top of the resonator 37 , 38 . This approach enables individual control of each oscillator in the network by suitably designing the corresponding patch antenna.…”

Phase cascade lattice rectifier array: an exactly solvable nonlinear network circuit

“…It has long been appreciated that rectifiers are nonlinear devices that break Lorentz reciprocity [1]. Interest in distributed energy networks [2], the need for alternative energy technologies [3,4], energy harvesting systems [5,6] and energy scavenging systems [7] have spurred renewed interest in the problem of scalability. New approaches to hierarchical control of AC and DC microgrids have in turn sparked innovation [8].…”

Phase Cascade Bridge Rectifier Array in a 2-D lattice

“…The need for DC electrical power generation from AC sources is arguably the most important nonlinear problem in modern society. Interest in distributed energy networks [1], alternative energy technologies [2,3] and the need for energy harvesting [5] and energy scavenging [6] systems has spurred renewed interest in the problem. A very large number of configurations have been investigated for power generation from AC source networks, and extend to wireless power generation [4,5], rectenna arrays [7,8] and smart grids [9].…”