Abstract: An apparatus and method for simultaneous detection of N gas species through laser radiation attenuation techniques is disclosed. Each of the N species has a spectral absorption band. N laser sources operate at a wavelength &lgr;N in a spectral absorption band separated by the cutoff wavelength for single-mode transmission. Each laser source corresponds to a gas species and transmits radiation through an optical fiber constructed and arranged to provide single-mode transmission with minimal power loss.

Abstract: A method for monitoring the high temperature reducing combustion atmosphere in a combustion process is disclosed. First, a spectral region for monitoring CO and H2O is identified. A laser wavelength is scanned so that a complete absorption transition includes a portion of the baseline. A laser is then referenced to an ITU-GRID. An output signal is generated from the laser and directed to a coupler to split the output signal in a predetermined ratio to a first component and a second component. The first component is directed to optics where it is shaped and collimated and then directed across a sample to be monitored to a detector that generates a measured output. The second component is directed to an absorption measurement device. The measured output is compared with the second component, and the temperature of the atmosphere and the concentration of the CO present in the atmosphere is calculated.

Abstract: One embodiment of a thermal management system comprises a heated body, where a heat energy is contained within this heated body. This first embodiment also comprises an ambient fluid adjacent to an exterior surface of the heated body. Walls forming a channel are disposed within an interior of the heated body. The heat contained in the heated body is moved into at least one of these channel walls. The first embodiment comprises a synthetic jet actuator adjacent to one of the channel walls. The synthetic jet actuator is positioned so as to direct a synthetic jet flow through the channel. The operation of the synthetic jet actuator creates a flow consisting of the ambient fluid though the channel. This flow of ambient fluid cools the walls of the channel and thereby also cools the heated body itself.

Abstract: Methods for creating one or more structures in a micromachined device. In one arrangement, the methods include the steps of providing a substrate, forming upstanding nonconductive mold walls on the substrate so that first and second wells are formed, the second well being wider than the first well. The method further includes applying a first material to the surface of the wells so that the first well fills with the first material before the second well, and removing the first material from the second well while leaving a portion in the first well.

Abstract: A micromachined structure having electrically isolated components is formed by thermomigrating a dopant through a substrate to form a doped region within the substrate. The doped region separates two portions of the substrate. The dopant is selected such that the doped region electrically isolates the two portions of the substrate from each other via junction isolation.

Abstract: Microneedle devices for transport of therapeutic and diagnostic materials and/or energy across tissue barriers, and methods for manufacturing the devices, are provided. The microneedles are hollow and/or porous and have diameters between about 10 nm and 1 mm. The microneedle devices permit drug delivery (or removal or sensing of body fluids) at clinically relevant rates across skin or other tissue barriers, without damage, pain, or irritation to the tissue. Microfabrication techniques are used to cost-effectively produce arrays of microneedles from metals, silicon, silicon dioxide, ceramic, and polymeric materials. Methods are provided for making porous or hollow microneedles.

Abstract: Methods for creating one or more structures in a micromachined device. In one arrangement, the methods include the steps of providing a substrate, forming upstanding nonconductive mold walls on the substrate so that first and second wells are formed, the second well being wider than the first well. The method further includes applying a first material to the surface of the wells so that the first well fills with the first material before the second well, and removing the first material from the second well while leaving a portion in the first well.

Abstract: The use of robust substrates on the surface micro-machined structures combines (1) the use of micro-machining technology; (2) the use of electronic packaging technologies; and (3) the use of conventional machining techniques to create a new class of micro-machined structures. A particular robust substrate-based micro-machine structure is a capacitive pressure sensor that includes a pressure sensitive diaphragm and an electrode.

Abstract: The present invention involves micromachined synthetic jet actuators, or “microjet” actuators. These fluidic control devices may be fabricated using standard silicon micromachining techniques and comprise an orifice situated atop an actuator cavity which is bounded at least partially by a flexible membrane. Alternatively, microjets may be formed in more robust substrates, such as metals or ceramics. Vibration of the membrane using either electrostatic or piezoelectric drives results in a turbulent air jet formed normal to the microjet orifice. The jet stream is synthesized by a train of vortex rings. Each vortex is formed by the motion of the diaphragm and is advanced away from the jet under self-induced velocity. Alternatively, the microjet actuator can comprise a “piston in cylinder” to take the functional place of the vibrating diaphragm. This can be accomplished by changing the aspect ratio of the actuator cavity to a deeper, more cylindrical shape.

Abstract: Microneedle devices are provided for transport of therapeutic and biological molecules across tissue barriers and for use as microflameholders. In a preferred embodiment for transport across tissue, the microneedles are formed of a biodegradable polymer. Methods of making these devices, which can include hollow and/or porous microneedles, are also provided. A preferred method for making a microneedle includes forming a micromold having sidewalls which define the outer surface of the microneedle, electroplating the sidewalls to form the hollow microneedle, and then removing the micromold from the microneedle. In a preferred method of use, the microneedle device is used to deliver fluid material into or across a biological barrier from one or more chambers in fluid connection with at least one of the microneedles. The device preferably further includes a means for controlling the flow of material through the microneedles.

Abstract: A resonant micro-compass for detecting the Earth's magnetic field while requiring minimal power is disclosed Generally, the micro-compass comprises a resonant structure that is driven at its resonant frequency, which requires minimal power. The resonant frequency of the resonant structure is then measured and the resonant structure is caused to oscillate. A magnet is located on the resonant structure such that introduction of the Earth's magnetic field to the oscillating resonant structure causes a reaction by the magnet which, in turn, changes the resonant frequency of the resonant structure to shift. This shift of resonant frequency is then measured, thereby allowing the micro-compass to detect the direction of the magnetic field with extreme accuracy.

Abstract: An electromagnetic system for a variety of applications can be formed through microfabrication techniques. Each segment of a conductive coil associated with an electromagnet is planar making it easy to fabricate the coil through microfabrication techniques. Furthermore, a plurality of magnetic fluxes generated by the electromagnet are dispersed across multiple points in order to reduce problems associated with flux density saturation, and the coil is positioned close to the magnetic core of the electromagnet in order to reduce problems associated with leakage. Accordingly, a low-cost, more efficient electromagnetic system can be batch fabricated through microfabrications techniques.

Abstract: Methods and apparatus are presented using tunable diode lasers for monitoring and/or controlling a high temperature process using an oxidizer containing O2 and organic fuel. Real-time monitoring of key species such as O2, CO, and H2O allow determination of the global or local stoichiometry, gas temperature, particulate concentration, and air entrainment levels into the process. Coupling the measured information with a control system provides a means for optimizing and controlling the process.

Abstract: Microneedle devices are provided for transport of therapeutic and biological molecules across tissue barriers and for use as microflameholders. In a preferred embodiment for transport across tissue, the microneedles are formed of a biodegradable polymer. Methods of making these devices, which can include hollow and/or porous microneedles, are also provided. A preferred method for making a microneedle includes forming a micromold having sidewalls which define the outer surface of the microneedle, electroplating the sidewalls to form the hollow microneedle, and then removing the micromold from the microneedle. In a preferred method of use, the microneedle device is used to deliver fluid material into or across a biological barrier from one or more chambers in fluid connection with at least one of the microneedles. The device preferably further includes a means for controlling the flow of material through the microneedles.

Abstract: An electromagnetic system for a variety of applications can be formed through microfabrication techniques. Each segment of a conductive coil associated with an electromagnet is planar making it easy to fabricate the coil through microfabrication techniques. Furthermore, a plurality of magnetic fluxes generated by the electromagnet are dispersed across multiple points in order to reduce problems associated with flux density saturation, and the coil is positioned close to the magnetic core of the electromagnet in order to reduce problems associated with leakage. Accordingly, a low-cost, more efficient electromagnetic system can be batch fabricated through microfabrications techniques.

Abstract: Several sensors are provided for determining one of a number of physical roperties including pressure, temperature, chemical species, and other physical conditions. In general, the sensors feature a resonant circuit with an inductor coil which is electromagnetically coupled to a transmitting antenna. When an excitation signal is applied to the antenna, a current is induced in the sensor circuit. This current oscillates at the resonant frequency of the sensor circuit. The resonant frequency and bandwidth of the sensor circuit is determined using an impedance analyzer, a transmitting and receiving antenna system, or a chirp interrogation system. The resonant frequency may further be determined using a simple analog circuit with a transmitter. The sensors are constructed so that either the resonant frequency or bandwidth of the sensor circuit, or both, are made to depend upon the physical properties such as pressure, temperature, presence of a chemical species, or other condition of a specific environment.

Abstract: A micromachined structure having electrically isolated components is formed by thermomigrating a dopant through a substrate to form a doped region within the substrate. The doped region separates two portions of the substrate. The dopant is selected such that the doped region electrically isolates the two portions of the substrate from each other via junction isolation.

Abstract: Briefly described, the present invention is concerned with cooling heated bodies and/or heated fluid with synthetic jet actuators in either open or closed systems. A first preferred embodiment of a cooling system of the present invention comprises a synthetic jet actuator directed to impinge directly on a heat producing (or heated) body. The synthetic jet actuator generates a synthetic jet stream comprised of cool ambient fluid that impinges on the heated surface thereby cooling this surface. As an example, the heated surface/body could be a microchip array in a microcomputer. After coming into contact with the heated surface, the fluid moves along the surface and is finally rejected to the ambient where it mixes and cools down. The synthetic jet may be incorporated into a modular unit that may be clipped on to a circuit board or other heat producing element to provide added, `ad hoc` cooling.

Abstract: Several sensors are provided for determining one of a number of physical properties including pressure, temperature, and other physical conditions. In general, the sensors feature a resonant circuit with an inductor coil which is electromagnetically coupled to a transmitting antenna. When an excitation signal is applied to the antenna, a current is induced in the sensor circuit. This current oscillates at the resonant frequency of the sensor circuit. The resonant frequency and bandwidth of the sensor circuit is determined using an impedance analyzer, a transmitting and receiving antenna system, or a chirp interrogation system. The resonant frequency may further be determined using a simple analog circuit with a transmitter. The sensors are constructed so that either the resonant frequency or bandwidth of the sensor circuit, or both, are made to depend upon the physical properties such as pressure, temperature, presence of a chemical species, or other condition of a specific environment.

Abstract: A reciprocating micro heat engine for electrical and mechanical power generation is disclosed The micro heat engine uses a reciprocating free piston that is driven by a periodic combustion process, and is implemented using micromachining technology. In the application of electrical power generation, the mechanical and electrical functionality of the engine are highly integrated; i.e., the same piston performs both the fuel-to mechanical energy conversion as well as the mechanical-to-electrical energy conversion.