Abstract: A microelectromechanical system (MEMS) accelerometer having separate sense and force-feedback electrodes is disclosed. The use of separate electrodes may in some embodiments increase the dynamic range of such devices. Other possible advantages include, for example, better sensitivity, better noise suppression, and better signal-to-noise ratio. In one embodiment, the accelerometer includes three silicon wafers, fabricated with sensing electrodes forming capacitors in a fully differential capacitive architecture, and with separate force feedback electrodes forming capacitors for force feedback. These electrodes may be isolated on a layer of silicon dioxide. In some embodiments, the accelerometer also includes silicon dioxide layers, piezoelectric structures, getter layers, bonding pads, bonding spacers, and force feedback electrodes, which may apply a restoring force to the proof mass region. MEMS accelerometers with force-feedback electrodes may be used in geophysical surveys, e.g.

Abstract: A method and apparatus for detecting underwater sounds is disclosed. An embodiment of the apparatus includes a substrate with a vacuum-sealed cavity. A support structure and an acoustic pressure sensor are situated on the substrate. The support structure of the apparatus may include a first oxide layer situated on the substrate, a silicon layer situated on the first oxide layer, and a second oxide layer situated on the silicon layer. The acoustic pressure sensor of the apparatus includes a first electrode layer situated on the substrate, a piezoelectric layer situated on the first electrode layer, and a second electrode layer situated on the piezoelectric layer. In one embodiment, the surface area of the second electrode layer is between about 70 to 90 percent of the surface area of the piezoelectric layer. In various embodiments, the support structure is thicker than the piezoelectric layer.

Abstract: According to embodiments of the present invention, an energy harvesting device is provided. The energy harvesting device includes a microchannel arranged to receive a fluid, a bluff body arranged to interact with the fluid flowing through the microchannel to generate a vortex fluid street, and an energy harvesting element arranged to interact with the vortex fluid street to harvest energy from the fluid. According to further embodiments of the present invention, a method of harvesting energy is also provided.

Abstract: A fully differential microelectromechanical system (MEMS) accelerometer configured to measure Z-axis acceleration is disclosed. This may avoid some of the disadvantages in traditional capacitive sensing architectures—for example, less sensitivity, low noise suppression, and low SNR, due to Brownian noise. In one embodiment, the accelerometer comprises three silicon wafers, fabricated with electrodes forming capacitors in a fully differential capacitive architecture. These electrodes may be isolated on a layer of silicon dioxide. In some embodiments, the accelerometer also includes silicon dioxide layers, piezoelectric structures, getter layers, bonding pads, bonding spacers, and force feedback electrodes, which may apply a force to the proof mass region. Fully differential MEMS accelerometers may be used in geophysical surveys, e.g., for seismic sensing or acoustic positioning.

Abstract: According to embodiments of the present invention, an energy harvesting device is provided. The energy harvesting device includes a plurality of energy harvesting elements, each energy harvesting element including a transducer, and at least one spring arranged in between at least two energy harvesting elements of the plurality of energy harvesting elements to mechanically couple the at least two energy harvesting elements to each other. According to further embodiments of the present invention, a method for forming an energy harvesting device is also provided.

Abstract: A microelectromechanical system (MEMS) accelerometer having separate sense and force-feedback electrodes is disclosed. The use of separate electrodes may in some embodiments increase the dynamic range of such devices. Other possible advantages include, for example, better sensitivity, better noise suppression, and better signal-to-noise ratio. In one embodiment, the accelerometer includes three silicon wafers, fabricated with sensing electrodes forming capacitors in a fully differential capacitive architecture, and with separate force feedback electrodes forming capacitors for force feedback. These electrodes may be isolated on a layer of silicon dioxide. In some embodiments, the accelerometer also includes silicon dioxide layers, piezoelectric structures, getter layers, bonding pads, bonding spacers, and force feedback electrodes, which may apply a restoring force to the proof mass region. MEMS accelerometers with force-feedback electrodes may be used in geophysical surveys, e.g.

Abstract: A fully differential microelectromechanical system (MEMS) accelerometer configured to measure Z-axis acceleration is disclosed. This may avoid some of the disadvantages in traditional capacitive sensing architectures—for example, less sensitivity, low noise suppression, and low SNR, due to Brownian noise. In one embodiment, the accelerometer comprises three silicon wafers, fabricated with electrodes forming capacitors in a fully differential capacitive architecture. These electrodes may be isolated on a layer of silicon dioxide. In some embodiments, the accelerometer also includes silicon dioxide layers, piezoelectric structures, getter layers, bonding pads, bonding spacers, and force feedback electrodes, which may apply a force to the proof mass region. Fully differential MEMS accelerometers may be used in geophysical surveys, e.g., for seismic sensing or acoustic positioning.

Abstract: A method and apparatus for detecting underwater sounds is disclosed. An embodiment of the apparatus includes a substrate with a vacuum-sealed cavity. A support structure and an acoustic pressure sensor are situated on the substrate. The support structure of the apparatus may include a first oxide layer situated on the substrate, a silicon layer situated on the first oxide layer, and a second oxide layer situated on the silicon layer. The acoustic pressure sensor of the apparatus includes a first electrode layer situated on the substrate, a piezoelectric layer situated on the first electrode layer, and a second electrode layer situated on the piezoelectric layer. In one embodiment, the surface area of the second electrode layer is between about 70 to 90 percent of the surface area of the piezoelectric layer. In various embodiments, the support structure is thicker than the piezoelectric layer.