Abstract: A method is presented for tracking an ingestible device in a gastrointestinal tract of a subject. The method includes: measuring acceleration of the ingestible device as it traverses through the gastrointestinal tract, for example using an accelerometer disposed in the ingestible device; computing a metric from the acceleration measurements obtained by the accelerometer over a given period of time; and identifying a location in the gastrointestinal tract based in part on the metric.

Abstract: A resonator comprising a magnetoelastic body having a mass load portion and an active resonating portion can be used in implementations such as a security tag. The resonator includes a mass at the mass load portion of the magnetoelastic body. Displacement of the magnetoelastic body is configured to occur at both the mass load portion and the active resonating portion. A strain at the active resonating portion during displacement is configured to be greater than a strain at the mass load portion during displacement.

Abstract: A capacitive sensor device is fabricated on a dielectric substrate. The capacitive sensor device may include multiple diaphragms that differ in shape and/or size. Each of the diaphragms is paired to upper and lower electrodes in included upper and lower electrode layers, respectively. The lower layer is on the dielectric substrate and couples the lower electrodes to a lower electrode terminal in parallel. The upper electrode layer is separated from the lower electrode layer by a gap defined by a removed sacrificial layer and couples the upper electrodes in parallel to an upper electrode terminal.

Abstract: An implantable actuation device that may be used with a glaucoma drainage device or attached to an ocular surface, a method of making an implantable actuation device, and a method of preventing cell adhesion resulting from a glaucoma treatment procedure. The implantable actuation device is made from a magnetoelastic material. Actuation of the magnetoelastic material may help control cellular adhesion that may develop and undesirably disrupt proper healing when recovering from invasive surgical treatments. The implantable actuation devices may have small form factors and customized geometries which include three-dimensional curvatures to help promote the actuation of liquid flow and facilitate the removal of unwanted cells.

Abstract: A resonator comprising a magnetoelastic body having a mass load portion and an active resonating portion can be used in implementations such as a security tag. The resonator includes a mass at the mass load portion of the magnetoelastic body. Displacement of the magnetoelastic body is configured to occur at both the mass load portion and the active resonating portion. A strain at the active resonating portion during displacement is configured to be greater than a strain at the mass load portion during displacement.

Abstract: A microfabricated gas flow structure includes an array of vertical gas flow channels in a side-by-side parallel flow arrangement. Adjacent gas flow channels are separated by a thin wall having a thickness which can be an order of magnitude or more less than the channel width, offering exceptionally high area efficiency for the array. Channel walls can be formed from a dielectric material to provide the walls with sufficient integrity at nanoscale thicknesses and to provide thermal insulative properties in the lateral direction, thereby controlling power losses when the gas flow structure is employed as a Knudsen pump. The gas flow structure can be microfabricated as a monolithic structure from an SOI wafer, with the gas flow channels formed in the device layer and the heat sink formed from the handle layer.

Abstract: An environmental logging system that includes a housing and an electronic logging circuit sealed within the housing. The logging circuit includes an energy source, transducer, charging circuit, trigger circuit, electronic control unit (ECU), and transmitter. The energy source is charged by the charging circuit using electricity from the transducer in response to external energy applied to the transducer. Commands may also be received by the circuit via the transducer. The ECU includes a processor, memory, and one or more sensors, and it operates under power from the energy source to store data from the sensor(s). The transmitter is coupled to the ECU and transmits the data via electromagnetic radiation outside the housing. The trigger circuit supplies operating power to the processor only when the voltage level of the energy source is above a minimum threshold. The housing may be a tubular shell filled with a polymeric material.

Abstract: A magnetoelastic tag includes a frame-suspended magnetoelastic resonator that combines a strong resonant response with a relatively small resonator, enabling magnetoelastic sensor use in a variety of inconspicuous applications and/or small packages. The resonator is suspended with respect to a substrate, which reduces, minimizes, or eliminates interaction between the substrate and resonator. Signal strength is thereby enhanced, thereby allowing miniaturization while maintaining a measurable response to the interrogation field. The resonator can have a hexagonal shape and/or be suspended at particular locations about its perimeter to promote signal generation in a direction different from that of the interrogation field. A sensor can include one or more frame-suspended resonators, which can be arranged in an array, stacked, or randomly where a plurality of resonators is employed.

Abstract: A fracture interrogation system includes an antenna adapted for placement in a subterranean wellbore and a plurality of pseudoparticles adapted for distribution with a proppant material into hydraulic fractures along the wellbore. The presence of the pseudoparticles in the hydraulic fractures is detectable by the antenna. The pseudoparticles can include a magnetoelastic resonator having a resonant frequency. An interrogation field excites the resonators at the resonant frequency for detection by the antenna. The same or a different antenna can act as the interrogation field source, and the system can be configured to operate in a talk-and-listen mode to better separate the response signal from the interrogation signal. Electromagnetic, mechanical, or acoustic impulses can be used to excite resonators of the pseudoparticles.

Abstract: An implantable actuation device that may be used with a glaucoma drainage device or attached to an ocular surface, a method of making an implantable actuation device, and a method of preventing cell adhesion resulting from a glaucoma treatment procedure. The implantable actuation device is made from a magnetoelastic material. Actuation of the magnetoelastic material may help control cellular adhesion that may develop and undesirably disrupt proper healing when recovering from invasive surgical treatments. The implantable actuation devices may have small form factors and customized geometries which include three-dimensional curvatures to help promote the actuation of liquid flow and facilitate the removal of unwanted cells.

Abstract: The distance between microscale electrodes can be determined from microdischarge current and/or capacitance distribution among a plurality of electrodes. A microdischarge-based pressure sensor includes a reference pair of electrodes on a body of the sensor and a sensing pair of electrodes. One of the electrodes of the sensing pair is on a diaphragm of the sensor so that the distance between the sensing pair of electrodes changes with diaphragm movement, while the distance between the reference pair does not. Plasma and current distribution within a microdischarge chamber of the sensor is sensitive to very small diaphragm deflections. Pressure sensors can be fabricated smaller than ever before, with useful signals from 50 micron diaphragms spaced only 3 microns from the sensor body. The microdischarge-based sensor is capable of operating in harsh environments and can be fabricated along-side similarly configured capacitive sensors.

Abstract: A sub-millimeter packaged microsystem includes a microsystem located in a sealed cavity defined between first and second portions of a micropackage. One or both micropackage portions can be fabricated from a metal suitable for use in a harsh environment, such as an oil well environment. The microsystem includes electronic components and can be configured to communicate with external components through a wall of the micropackage by wireless communication or by conductive feedthroughs. Pluralities of microsystems, first micropackage portions, and/or second micropackage portions are simultaneously placed during a batch assembly process. The assembly process may include micro-crimping the first and second micropackaging portions together without the need for bonding materials and related process steps.

Abstract: A strain sensor having an active area that includes a magnetoelastic resonator and spring configured so that the spring undergoes a greater amount of strain than the resonator when the sensor is under load. The sensor is anchored at opposite ends of the active area to a substrate for which strain is to be measured. An interrogating coil is used for wireless sensor readout. A biasing magnet may be included to provide a desired sensor response for the particular application of the sensor. The strain sensor may be implemented as a differential strain sensor that includes a second, strain-independent reference resonator.

Abstract: An environmental logging system that includes a housing and an electronic logging circuit sealed within the housing. The logging circuit includes an energy source, transducer, charging circuit, trigger circuit, electronic control unit (ECU), and transmitter. The energy source is charged by the charging circuit using electricity from the transducer in response to external energy applied to the transducer. Commands may also be received by the circuit via the transducer. The ECU includes a processor, memory, and one or more sensors, and it operates under power from the energy source to store data from the sensor(s). The transmitter is coupled to the ECU and transmits the data via electromagnetic radiation outside the housing. The trigger circuit supplies operating power to the processor only when the voltage level of the energy source is above a minimum threshold. The housing may be a tubular shell filled with a polymeric material.

Abstract: A sub-millimeter packaged microsystem includes a microsystem located in a sealed cavity defined between first and second portions of a micropackage. One or both micropackage portions can be fabricated from a metal suitable for use in a harsh environment, such as an oil well environment. The microsystem includes electronic components and can be configured to communicate with external components through a wall of the micropackage by wireless communication or by conductive feedthroughs. Pluralities of microsystems, first micropackage portions, and/or second micropackage portions are simultaneously placed during a batch assembly process. The assembly process may include micro-crimping the first and second micropackaging portions together without the need for bonding materials and related process steps.

Abstract: A fracture interrogation system includes an antenna adapted for placement in a subterranean wellbore and a plurality of pseudoparticles adapted for distribution with a proppant material into hydraulic fractures along the wellbore. The presence of the pseudoparticles in the hydraulic fractures is detectable by the antenna. The pseudoparticles can include a magnetoelastic resonator having a resonant frequency. An interrogation field excites the resonators at the resonant frequency for detection by the antenna. The same or a different antenna can act as the interrogation field source, and the system can be configured to operate in a talk-and-listen mode to better separate the response signal from the interrogation signal. Electromagnetic, mechanical, or acoustic impulses can be used to excite resonators of the pseudoparticles.

Abstract: A magnetoelastic tag includes a frame-suspended magnetoelastic resonator that combines a strong resonant response with a relatively small resonator, enabling magnetoelastic sensor use in a variety of inconspicuous applications and/or small packages. The resonator is suspended with respect to a substrate, which reduces, minimizes, or eliminates interaction between the substrate and resonator. Signal strength is thereby enhanced, thereby allowing miniaturization while maintaining a measurable response to the interrogation field. The resonator can have a hexagonal shape and/or be suspended at particular locations about its perimeter to promote signal generation in a direction different from that of the interrogation field. A sensor can include one or more frame-suspended resonators, which can be arranged in an array, stacked, or randomly where a plurality of resonators is employed.

Abstract: A microfabricated gas flow structure includes an array of vertical gas flow channels in a side-by-side parallel flow arrangement. Adjacent gas flow channels are separated by a thin wall having a thickness which can be an order of magnitude or more less than the channel width, offering exceptionally high area efficiency for the array. Channel walls can be formed from a dielectric material to provide the walls with sufficient integrity at nanoscale thicknesses and to provide thermal insulative properties in the lateral direction, thereby controlling power losses when the gas flow structure is employed as a Knudsen pump. The gas flow structure can be microfabricated as a monolithic structure from an SOI wafer, with the gas flow channels formed in the device layer and the heat sink formed from the handle layer.

Abstract: The distance between microscale electrodes can be determined from microdischarge current and/or capacitance distribution among a plurality of electrodes. A microdischarge-based pressure sensor includes a reference pair of electrodes on a body of the sensor and a sensing pair of electrodes. One of the electrodes of the sensing pair is on a diaphragm of the sensor so that the distance between the sensing pair of electrodes changes with diaphragm movement, while the distance between the reference pair does not. Plasma and current distribution within a microdischarge chamber of the sensor is sensitive to very small diaphragm deflections. Pressure sensors can be fabricated smaller than ever before, with useful signals from 50 micron diaphragms spaced only 3 microns from the sensor body. The microdischarge-based sensor is capable of operating in harsh environments and can be fabricated along-side similarly configured capacitive sensors.

Abstract: A strain sensor having an active area that includes a magnetoelastic resonator and spring configured so that the spring undergoes a greater amount of strain than the resonator when the sensor is under load. The sensor is anchored at opposite ends of the active area to a substrate for which strain is to be measured. An interrogating coil is used for wireless sensor readout. A biasing magnet may be included to provide a desired sensor response for the particular application of the sensor. The strain sensor may be implemented as a differential strain sensor that includes a second, strain-independent reference resonator.