Abstract: Zero power wireless sensors, devices, and systems are used for crop water content monitoring. The sensors consume no power while monitoring for the presence of dry crop conditions. Infrared reflectance from plants is measured and when selected spectral conditions are met, a circuit is closed, activating an alarm, an RFID tag, or a radio transmitter. The deployed sensors consume no power while monitoring, reducing or eliminating the need to change batteries.

Abstract: A microwave oven and a method of operating the same is provided herein. The method includes the steps of: sensing that a door of the microwave is in an open state; interrupting a power input to a generator power supply unit comprising a first converter, a first energy reserve, a second energy reserve located downstream from the first energy reserve, and a second converter located between the first and second energy reserves; detecting an input voltage; and disabling the second converter if the detected input voltage is less than a threshold voltage that is proportional to the detected input voltage, wherein disabling the second converter triggers the second energy reserve to discharge, and wherein the time necessary to discharge the second energy reserve is free of influence from the first energy reserve and is independent of the detected input voltage.

Abstract: A microwave oven and a method of operating the same is provided herein. The method includes the steps of: sensing that a door of the microwave is in an open state; interrupting a power input to a generator power supply unit comprising a first converter, a first energy reserve, a second energy reserve located downstream from the first energy reserve, and a second converter located between the first and second energy reserves; detecting an input voltage; and disabling the second converter if the detected input voltage is less than a threshold voltage that is proportional to the detected input voltage, wherein disabling the second converter triggers the second energy reserve to discharge, and wherein the time necessary to discharge the second energy reserve is free of influence from the first energy reserve and is independent of the detected input voltage.

Abstract: A sensing device is provided having sensing circuitry, connected to an input port and the output port, with a sensor having an impedance sensitive to a parameter of interest, one or more passive electrical components, and a variable capacitor. The sensing circuitry is triggered to generate an output signal for transmission from the output port, the output signal dependent on the parameter of interest sensed by the sensor and on an input power value, Pin, of an input signal received at the input port being greater than a parametric threshold power value, Pth. A sensing system includes the sensing device and a transmitting device to transmit the input signal to the sensing device at a frequency representative of the parameter of interest. A receiving device, which can be incorporated with or located remotely from the transmitting device, receives the output signal of the sensing device, which has a frequency that is half of the frequency of the input signal transmitted by the transmitting device.

Abstract: Devices for ultrasonic transmission and/or reception having a piezoelectric micromachined ultrasonic transducer (pMUT). The device employs a material such as lithium niobate as a piezoelectric layer in a membrane suspended over a cavity. Two activation electrodes on an upper surface of the membrane can activate one or more flexural modes of mechanical vibration in the membrane, the flexural modes of vibration including a displacement in a cross-sectional plane of the membrane. The device can be used individually or in an array. The device can be configured for use in a liquid medium or in biological tissue. A method of operating an ultrasonic transducer is provided. A method of fabrication of an ultrasonic transducer is provided.

Abstract: A zero-power plasmonic microelectromechanical system (MEMS) device is capable of specifically sensing electromagnetic radiation and performing signal processing operations. Such devices are highly sensitive relays that consume no more than 10 nW of power, utilizing the energy in detected electromagnetic radiation to detect and discriminate a target without the need of any additional power source. The devices can continuously monitor an environment and wake up an electronic circuit upon detection of a specific trigger signature of electromagnetic radiation, such as vehicular exhaust, gunfire, an explosion, a fire, a human or animal, and a variety of sources of radiation from the ultraviolet to visible light, to infrared, to terahertz radiation.

Abstract: Ultra-low power methods and sensor devices are provided for determining the presence and magnitude of electromagnetic radiation or other signals. The sensor devices and methods provide both qualitative and quantitative analyses and can be deployed in remote locations for continuous monitoring over years without requiring a replacement power supply.

Abstract: Tunable delay circuit devices have an input port, an output port, at least three parallel paths connecting the input port and the output port, on each path, an input switch and an output switch, and on each path, a plurality of shunt resonant tanks connected between the input switch and the output switch, each shunt resonant tank periodically chargeable from the input port and dischargeable to the output port by operation of the input switch and the output switch.

Abstract: An ultra-miniaturized, low-cost, and maintenance-free chemical sensor is capable of continuously monitoring the concentration of specific volatile organic compound (VOC) vapors released from crop plants and green plants under distress from pests or disease. The sensor is based on micromechanical structures and relies on the mechanical actuation induced by the chemical interaction between the VOCs and materials in the microstructure to passively generate a wake-up bit when the concentration of VOCs exceeds a predetermined value. The sensor does not consume power while in standby mode (i.e., when certain VOC vapors are not present), and wirelessly communicates the location of impending outbreaks upon detection of a predetermined concentration of certain VOC vapors.

Abstract: Adaptive RF filters based on modulated resonators are provided. The filter architecture is based on time-interleaved commutation of passive RF resonators. The architecture can behave as a two-port filter network, with a fully tunable instantaneous filter bandwidth. The filters are applicable as miniaturized, environment-aware RF signal processing components and can be used in mobile communications.

Abstract: Zero-power system for remote monitoring of heat sources is provided. The systems detect failure indicators of remote equipment including power substations, oil rigs, large inaccessible machinery in a factory, and communications equipment. The systems also can be used to detect the presence of people in buildings or in other locations, so as to improve HVAC utilization in large buildings. When the zero-power monitoring systems detect heat sources, such as the presence of people, failure indicators, or a targeted environmental signal, a circuit is closed using the energy of the detected radiation, and activating an RFID tag, a radio transmitter, or an alarm. The monitoring systems can remain deployed and active for many years without the need for battery replacement.

Abstract: Tunable delay circuit devices have an input port, an output port, at least three parallel paths connecting the input port and the output port, on each path, an input switch and an output switch, and on each path, a plurality of shunt resonant tanks connected between the input switch and the output switch, each shunt resonant tank periodically chargeable from the input port and dischargeable to the output port by operation of the input switch and the output switch.

Abstract: Zero power wireless sensors, devices, and systems are used for crop water content monitoring. The sensors consume no power while monitoring for the presence of dry crop conditions. Infrared reflectance from plants is measured and when selected spectral conditions are met, a circuit is closed, activating an alarm, an RFID tag, or a radio transmitter. The deployed sensors consume no power while monitoring, reducing or eliminating the need to change batteries.

Abstract: A resonator system is provided in which a combined overtone resonator device is excited with a two-dimensional mode of mechanical vibration in a cross sectional plane of a piezoelectric plate in response to an alternating voltage applied through an interdigitated electrode. The cross sectional plane extends along the width direction and the thickness direction, and the two-dimensional mode of mechanical vibration is a two-dimensional combined overtone mode of second and third order asymmetrical Lamb-wave overtones.

Abstract: A transformer including a piezoelectric plate and interdigital electrodes is provided. The interdigitated electrodes includes a plurality of conductive strips disposed over the piezoelectric plate. A cross-sectional Lamé mode resonance is excited in a cross sectional plane of the piezoelectric plate in response to input voltage applied through the interdigitated electrode, producing a voltage gain. A device including the aforementioned transformer is also provided.

Abstract: A sensing device is provided having sensing circuitry, connected to an input port and the output port, with a sensor having an impedance sensitive to a parameter of interest, one or more passive electrical components, and a variable capacitor. The sensing circuitry is triggered to generate an output signal for transmission from the output port, the output signal dependent on the parameter of interest sensed by the sensor and on an input power value, Pin, of an input signal received at the input port being greater than a parametric threshold power value, Pth. A sensing system includes the sensing device and a transmitting device to transmit the input signal to the sensing device at a frequency representative of the parameter of interest. A receiving device, which can be incorporated with or located remotely from the transmitting device, receives the output signal of the sensing device, which has a frequency that is half of the frequency of the input signal transmitted by the transmitting device.

Abstract: Provided herein are systems and method for producing models that infer health scores for health metrics for a subject. A first model, using raw feature data derived from the subject, infers feature cluster scores for each of a plurality of feature clusters in a feature group. A second model, using the inferred feature cluster scores, infers a heath score for a health metric.

Abstract: A solid state radio frequency generation system is provided for an electromagnetic cooking device having an enclosed cavity. The radio frequency generation system includes: an RF feed for introducing electromagnetic radiation into the cavity to heat a food load; a high-power RF amplifier coupled to the RF feed, the amplifier comprising at least one amplifying stage configured to output a signal that is amplified in power with respect to an input RF signal; a small signal generator for supplying the input RF signal to the amplifier; and a switching power supply unit including a single DC-DC converter that converts AC mains power to low voltage DC for supply to the amplifier, and a controller configured to adapt an input current from the AC mains power to form a predefined periodic waveform with the same frequency as the AC mains power for supply to the small signal generator.

Abstract: Implantable bio-heating and intrabody communication systems use arrays of piezoelectric micromachined ultrasonic transducers (pMUTs) to provide ultrasound-based diagnosis and treatment of medical conditions. Systems involving one or more pMUT arrays can be implanted into the body or integrating into smart ingestible pills to enable monitoring of a medical condition and/or continuous or intermittent application of hyperthermia and other treatments.

Abstract: Adaptive RF filters based on modulated resonators are provided. The filter architecture is based on time-interleaved commutation of passive RF resonators. The architecture can behave as a two-port filter network, with a fully tunable instantaneous filter bandwidth. The filters are applicable as miniaturized, environment-aware RF signal processing components and can be used in mobile communications.