Research Terms
The University of Central Florida invention is a new class of piezoelectric microelectromechanical system (MEMS) resonators using a temperature-stable and very high-quality factor (low noise) platform. The thin-film suspended microacoustic resonators are engineered on low-cost substrates, making them very commercially attractive.
Quartz resonators enable precise frequency control in timing applications but are costly, large, and offer limited flexibility. One alternative is MEMS resonators which are typically capacitively driven and result in higher loss and increased power consumption. MEMS resonators are also sensitive to temperature fluctuations, leading to frequency drift and reduced accuracy. One other alternative is piezoelectrically driven MEMS resonators, which can provide lower loss and potentially better noise performance. However, the devices show temperature stability and noise performance that should be addressed before being considered viable replacements for both quartz and current capacitive MEMS options.
As a solution, the UCF invention addresses the noise performance and temperature stability of MEMS by using a novel piezoelectric on a substrate resonant structure. The innovation comprises a relatively thick, low-loss substrate with a thin-film piezoelectric overlay.
The piezoelectric film not only provides the transduction mechanism but also functions as an anchor for holding the resonant body (comprising at least the thick substrate, thin-film piezoelectric, and one or more electrodes) suspended and attached to the substrate. This anchoring configuration solves the long-standing problem of increased noise of piezoelectric MEMS resonators due to anchor loss, which is the loss of acoustic (mechanical) energy through the anchoring points.
Partnering Opportunity: The research team is seeking partners for licensing, research collaboration, or both.
Researchers at the University of Central Florida have invented a passive wireless sensor system that includes a piezoelectric microelectromechanical systems (MEMS) resonator that can be configured to sense one or more physical parameters such as temperature, pressure, viscosity and mass. This system is complementary metal oxide semiconductor based, which uses silicon substrates and fab line processing techniques, and is thus significantly less expensive than other MEMS sensors. Additionally, this invention is smaller, typically less than a few square micrometers, and can potentially be used as medical implants. Compared to LC tank technology, this system provides measurements with higher resolutions and can be utilized at higher resolution and operating ranges. Due to their small size, these sensors do not waste any of the received energy to power up electronic circuitries.
Most commercial sensors need batteries to operate which, in turn, limits their life spans. The UCF device is wireless, requires no regular maintenance, and has no required minimum power for operation. Because of these features, the sensors can be placed on moving parts located inside an engine and inside rotating objects such as tires. Along with its antenna, this sensor system can be configured to operate at most common desired frequencies, based on the application. Furthermore, several separate sensors with multiple frequencies and independent measurements can be assembled onto one substrate.
Technical Details
The UCF invention includes a base unit (or a transceiver) and a lateral-extensional MEMS resonator (sensing element) connected directly to an antenna with no additional components or power source. The base unit wirelessly transmits an RF signal to the sensor and analyzes the received signal. It harvests energy from the received RF signal to operate and then transmits the data back to the base unit within a few microseconds.
Researchers at the University of Central Florida have developed a novel, low-cost acoustoelectric (AE) amplification scheme that resolves the issues found in transistor-based amplifiers and existing AE amplification systems. All transistor-based amplifiers suffer from a decrease in optical power (gain) as the frequency increases, and though current AE amplification systems can provide greater gain-frequency, they have low operating efficiency and low electromechanical coupling.
In contrast, the UCF AE amplification mechanism operates more efficiently and offers higher gains as the frequency increases. Using lateralextensional thin-film piezoelectric-on-silicon (TPoS) resonant cavities, the invention amplifies bulk acoustic waves in a structure with high electromechanical coupling. As a result, the innovation enables transistor-less amplification at both lower and higher frequencies and non-reciprocal devices. Manufacturers can use the new scheme to build more cost-effective, low-power, low-loss devices for communications, wireless sensors, and the Internet of Things (IoT). Example acoustic devices include unilateral amplifiers, zero-loss filters, oscillators, and circuit-less, high-detection range wireless sensors.
Technical Details
The new UCF apparatus comprises a semiconductor layer and a thin piezoelectric layer (such as TpoS) deposited/bonded onto the semiconductor layer to form an acoustic cavity. Within the composite structure, the energy exchange between the propagating acoustic waves of the piezoelectric medium and the charge carriers in the semiconductor would normally lead to acoustoelectric loss. However, by pumping energy into the semiconductor layer to form an electric field across it, the velocity of the charge carriers exceeds that of the acoustic waves. As a result, the energy transfer reverses (from the charge carriers to the acoustic waves), effectively amplifying the acoustic waves, so that as the frequency of operation increases, the achievable gain also increases.
In one example setup, the thin piezoelectric layer consists of 1 _m (20 percent) of scandium doped aluminum nitride (Sc0.2Al0.8N), and the semiconductor layer comprises 2 _m of lightly doped n-type Si. Access pads inject DC current into the semiconductor layer to form an electric field in parallel with the direction of acoustic wave propagation in the semiconductor layer.
Partnering Opportunity
The research team is looking for partners to develop the technology further for commercialization.
Stage of Development
Prototype available.
Researchers at the University of Central Florida have designed a wireless sensor that can accurately detect and transmit an object's acceleration or vibration without using on-board (wired) power sources or batteries with little to no maintenance required. Most commercial sensors need batteries to operate which, in turn, limits their life spans. In contrast, the UCF device operates by using energy that it receives wirelessly, so it requires no regular maintenance and can operate at ultra-low power.
Smaller, lighter and cheaper to build than other wireless accelerometers, the UCF sensor can be placed on moving parts inside an engine, in rotating objects such as tires, and in other hard-to-reach places that require regular maintenance. The design also enables operation at most frequencies, based on the application. Additionally, the design enables manufacturers to assemble several separate sensors with multiple frequencies and independent measurements onto one substrate. In one example use, the device could enable hospitals or parents to monitor newborns who are at risk for sudden infant death syndrome (SIDS).
Technical Details
The UCF invention consists of a microelectromechanical system (MEMS) piezoelectric-based resonator coupled with a mechanically-variable capacitor that is directly connected to a dipole antenna or an oscillator circuit. The sensor receives energy from a nearby transceiver, and the reflected signal contains the resonance frequency of the resonator, which is a function of the acceleration of the sensor. When mounted on a moving object, the sensor detects and translates movements/accelerations into movements of a lumped mass that forms the moving electrode of the variable capacitor and results in a change of capacitance/impedance. The transceiver wirelessly monitors the shift of frequency, extracting acceleration/displacement.
The system achieves wireless sensing by transmitting a sinusoidal interrogation signal from the transceiver to the sensor and receiving/analyzing the reflected signal. Using the interrogation signal, the sensor antenna energizes the sensor, which can then operate without needing an external power source. When the frequency of the interrogation signal equals the resonance frequency of the MEMS resonator, maximum energy transfer occurs. Once the interrogation signal is turned off, the resonator operates at its natural resonance frequency, allowing it to transmit a decaying sinusoidal signal to the receiver antenna. When the antenna receives the signal, the system extracts the resonance frequency of the resonator using Fast Fourier Transform (FFT) analysis. The system then adjusts the frequency of the interrogation signal for the next reading accordingly, to energize the sensor efficiently.
Partnering Opportunity
The research team is looking for partners to develop the technology further for commercialization.
The UCF invention relates to Radio Frequency (RF) Power Sensing and Scavenging Based on Phonon-Electron Coupling in Microscale Waveguides. The new method for RF power sensing and scavenging takes advantage of the energy exchange mechanism between microacoustic waves (which support the majority of today’s RF signal processing in frontend modules) and electrons. In this scheme, proportional to the power of the RF signal, a DC signal is generated and can be immediately read for monitoring purposes or supplied to a subsequent stage. This RF to DC conversion is performed in a completely passive manner in a sub-millimeter footprint and within a lithographically defined frequency range. This allows for its integration in ultra-low power and miniaturized wireless transceivers or for reducing the reliance on batteries, which is hindering the expansion of the internet of things (IoT).
Partnering Opportunity
The research team is seeking partners for licensing and/or research collaboration.
Stage of Development
Prototype available.
The University of Central Florida invention is a method and apparatus for self-interference cancellation (SIC). Today’s more stringent frequency band allocation and full-duplex wireless communication have made self-interference cancellation critical since the reception and transmission occur at close bands or simultaneously on the same channel. Suppressing such undesired transmitted signals from overwhelming the reception calls for analog or digital self-interference cancellation schemes is vital.
As a solution, the UCF invention converts the transmission signal into a mechanical or acoustic signal, reducing the footprint by orders of magnitude. The converted signal goes into an acoustic waveguide assembly that includes one or more acoustic waveguides to generate the self-interference cancellation signal. That signal could be converted back into an electromagnetic radio frequency signal before being combined with (subtracted from) the received signal to cancel interference. The acoustic waveguide assembly can support many taps, hundreds or more, in a small footprint.
Partnering Opportunity
The research team is seeking partners for licensing, research collaboration, or both.
Stage of Development
Prototype available.
