Research Terms
Solar Energy Engineering Materials Engineering Materials Sciences Mechanical Engineering Optical Engineering Physical Sciences Optics Physics Laser Physics
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Advanced Materials & Products Solar Photonics/Optics
Researchers at the University of Central Florida have invented a new material and processing technique to reduce electrical conductivity and eddy currents by making the surface frequency selective. Induction heating occurs when eddy currents heat conductive material due to the inherent electrical resistance. The traditional use of a highly conductive metallic material slightly reduces induction heating by reducing the amount of energy introduced into the material via the skin effect, but the resulting induction heating may still be too high for certain applications. For example, MRI-induced induction heating, which is more severe at metal tips, causes thermal damage to tissues of patients wearing implants that have leads, such as in spinal fusion stimulators, cardiac pacemakers, and neurostimulation systems. Thus, there is a need for a material that has better biocompatibility and electrical resistivity.
Technical Details
The invention contains a substrate material with an outer surface and a modified surface layer, comprising the substrate material plus a metal or metal alloy. Within medical applications, surface modification results in a more reflective, electrically resistive surface of medical components including medical implants (such as the lead wire of a pacemaker) and medical tools (needles, knives, tongs), reducing induction heating that occurs in rapidly time-varying electromagnetic fields in MRI and magnetic resonance tomography (MRT). This material also provides enhanced MRI visibility for implants including stents and bone-repairing fixtures by reducing the blurring that occurs near metallic objects.
In other applications, including sensors, detectors, and energy-related applications, this technique can be used to modify surfaces to selectively increase absorption in electromagnetic waves within particular wavelengths and to boost energy efficiency. This invention includes a frequency selective surface (FSS)-based metamaterial containing modified surfaces that are arranged to create a resonant frequency.
Researchers at the University of Central Florida have developed a photodetector able to operate at room temperature and measure spectral ranges including microwave, THz, SWIR, MWIR, and LWIR while maintaining image detail. Current commercial photodetectors are limited by the sensor's spectral responsivity, requiring multiple sensors or unique configurations to image and sense a wide spectral range. A new nanostructured sensor design fundamentally improves responsivity while providing a simpler and more cost-effective approach than existing products.
Formed on the surface of a silicon wafer by laser processing, 3D nanostructures enhance collection efficiency while enabling multi-wavelength absorption via varyingly doped band sections, each contributing to the total spectrum detectable by the sensor. This high detectivity is coupled with high sensitivity, represented by the sensor's low noise equivalent temperature difference (NETD), providing high signal-to-noise data for uses including: military applications, nondestructive testing, process control in manufacturing, and biomedical imaging.
Technical Details
The 3D sensor structure is fabricated by the use of laser-assisted deposition (LAD) and laser-assisted dopant incorporation (LADI). The laser processing creates an array of conical, pyramidal, or other 3D shapes to enhance surface area and responsivity. The sensor detects a range of wavelengths as specified by means of user-customizable magnetic doping in ring-like sections along the vertical axis of the structure. An array of structures with various dopant materials and concentrations can operate over a wide range of wavelengths and comprise a focal plane array. The fundamental nature of the sensor's 3D nanostructure and magnetic dopant rings extends beyond photodetection to detection using polarization, static magnetic field detection, and gas and pressure detection featuring passive or active sensing modes.
Researchers at the University of Central Florida have invented a novel additive manufacturing system and methods for thin film fabrication specifically useful in fabricating higher performance solar photovoltaic (PV) cells at a fraction of the cost of traditional PV cell manufacturing methods. Today's commercial solar cells are expensive to produce ($100-$400 per m2) and typically have low conversion efficiency (15-20 percent). With the new Laser-Assisted Manufacturing Process Using Microfluidic Suspensions and Dry Powders, companies can make next-generation PVs, such as Intermediate Band Solar Cells (IBSCs), for far less (approximately $30 per m2). More importantly, IBSCs have high conversion efficiency (~50 percent).
The invention comprises a system and methods of fabricating additively manufactured structures using a roll-to-roll process technology and a unique and novel laser electrospray printhead. The inventive concept accommodates scalable large structures, wherein cylinders (feed and take-up spools) move or roll a substrate through an electrospray module. The module deposits microdroplets of nanoparticles onto the substrate through both hydrodynamic and electrodynamic shear. The electrospray module can operate in a steady cone-jet spray mode and a micro-dripping mode, depending on the manufacturing requirements. As the substrate moves, an annular laser beam dries and sinters the wet nanoparticles, fusing them onto the substrate one layer at a time. To focus the laser beam, the system uses either a hollow parabolic mirror or a hollow flat mirror and an annular lens, as required. The same concept can produce regular arrays of microdots and nanodots.
Researchers at the University of Central Florida have designed a new imaging system that captures detailed, 3D views of an object's internal structures and is more affordable, compact and transportable than other systems. The invention is safe to use for both medical and scientific applications, since it does not require a radioactive source to create an image. For example, the system could visualize biological structures such as blood vessels, clots and internal hemorrhaging in a patient or detect and identify implanted medical devices. It may also enable the nondestructive testing and analysis of embedded electronic circuits and be used in identifying building defects, such as internal cracks or voids.
Today's imaging devices, such as magnetic resonance imaging (MRI) systems and other nuclear magnetic resonance techniques, are complex, expensive systems that require a strong magnetic field with a large detector coil and a spatial encoding signal to determine the location of a particular image pixel. In contrast, the UCF invention employs a simpler design that uses smaller, less costly components, including a radio-frequency (RF) magnetic field radiator and a novel loop-shaped, resistive foil bolometer detector array. As well, the system does not require additional structures (like wave guides) to increase bolometer sensitivity, compared to existing uncooled metal foil RF bolometers.
The unique imaging system consists of an RF transmission source (such as a magnetic field radiator), an uncooled, loop-shaped, resistive foil bolometer detector array, an image processor, and a display. As shown in the example figure, an object of interest is positioned between the RF transmission source and the loop bolometer array. During operation, RF signals generated by the transmission source pass through the object, causing spatially varying flux density at the loop elements. The local flux density at a particular loop element induces current within the loop, causing Joule heating that results in a detectable resistance change within a bolometer circuit. The output is converted to a pixel intensity which is then combined spatially with the remaining elements to produce a composite "magnetic image."
Uncooled Resistive Metal Foil Bolometers for Imaging with Radiofrequency Magnetic Fields, SPIE Commercial + Scientific Sensing and Imaging conference, 2018, Orlando, Florida, USA, Proceedings Volume 10656, Image Sensing Technologies: Materials, Devices, Systems, and Applications V; 106560F (2018) https://doi.org/10.1117/12.2305042
Researchers from the University of Central Florida and the United States Navy have invented an optical detection system designed to identify and quantify the chemicals in a gas mixture from a distance and in real time. The new system can provide a 3D mapping/readout of the mixture's different chemical concentrations, volume and location. Able to detect chemicals over a broad spectral range, the system is also tunable and does not require cooling. Thus, it can be used under various conditions, such as high temperatures and pressures. For example, the system could be used to identify chemical gas leaks in submarines, spacecrafts, or the breathing system of a pilot's air supply. The innovation is a less costly, simpler solution to achieving such capabilities compared to current technologies, which require customized instrumentation to detect specific chemicals.
The invention is a detection system for identifying and quantifying chemicals in a gas sample and methods for making and operating the system. It comprises a new hyperdoped semiconductor optical sensor with a laser for photoexcitation of the gas mixture, a reference laser source, and a processor. Other configurations may include a multi-core optical fiber that is coupled with the photodetectors.
In one example application of the invention, a distant chemical cloud is irradiated with a modulated pump laser beam of a specific wavelength. A doped crystalline silicon carbide (SiC) photodetector receives photons emitted from the photoexcited chemicals in the cloud. Then a probe laser beam sends a modulated optical signal to the photodetector, which then provides an output signal to a second photodetector. A variety of information about the chemical compounds is extracted from the measured data of the second detector and sent to a processor, which identifies the chemicals, their volume and concentrations. The processor also provides a 3D model of the gas sample.
The University of Central Florida invention comprises methods and structures for new optical components that may embed the following: (1) anti-reflection (AR) materials during an additive manufacturing process, (2) monitoring elements for thermal control, or (3) optical components to enhance functionality and performance.
A new method of signal amplification has been developed by a UCF researcher to offer improved signal amplification utilizing optical gain rather than traditional gain in the detector. The novel approach to optical signal amplification does not require active electronic elements, avoiding problems such as thermal run away that can cause a detector to become inoperative in harsh environments. Additionally, the technology includes embodiments requiring no power, allowing the sensor to operate for an indefinite period of time. Applications of this sensor include detection of neutrons, control and monitoring of nuclear reactors and fuel processing, characterization of nuclear fuel rods, and detection of concealed fissile and radioactive materials.
Technical Details
This method of optical signal amplification detects incident photons through absorption, increasing the carrier concentration, thereby modulating the index of refraction and the reflectivity of the semiconductor in a way that can be monitored externally. By operating without the need for other active electronic elements on the photodetector, the device eliminates the concern over active elements’ risk of operational problems compared to passive elements. It enhances detection of weak electromagnetic (EM) signals by amplifying the signal optically instead of traditional electrical amplification. Operating on the principle of photoexcitation, it transfers electrons from the dopant energy level to the conduction band or from the valance band to the dopant energy level, for n- and p-type dopants, respectively. When paired with a laser beam on the semiconductor surface from a diode laser or other source, the device changes the electron density in the conduction of valence bands, which then changes both the refractive index and the semiconductor's reflectivity, resulting in an amplified signal output.
The University of Central Florida invention is a method and system for forming surface-modified substrates for various applications. For example, companies can use the technologies to develop materials for medical devices and tools used in surgical applications in magnetic resonance imaging (MRI) environments. MRI scanners generate 3D images of a patient’s internal anatomy (such as tissues and organs), enabling doctors to detect diseased tissues, such as tumors. However, some metals in medical materials are susceptible to the induction heating caused by MRI scans. The heat (generated by electric “eddy currents” from a time-varying magnetic field) can affect patients wearing implants with leads, such as spinal fusion stimulators, cardiac pacemakers, and neurostimulation systems. As a solution, the UCF invention offers ways to modify surfaces and effectively produce and use materials in medical applications that reduce MRI-related induction heating.
Technical Details: The UCF invention comprises a method of forming surface-modified substrates by laser diffusion processing and a system for performing the modifications. In one example application, the substrate is medical-grade material (M). The material’s outer surface is modified with another metal material (X), such as platinum (Pt), palladium (Pd), gold (Au) or silver (Ag). With two or more different Xs, the other material can comprise a metal alloy. The system for forming substrates includes a laser system and a laser processing chamber. A laser scanner automatically controls the laser beam position or an x-y translating stage on which the laser processing chamber is mounted for scanning the laser beam relative to the substrate material (M). In the example, the surface-modified substrate is for a medical implant (such as the lead wire of a pacemaker) or a surgical tool (needle, knife, tongs). A coating of at least one metal (X) is deposited onto the outer surface and is irradiated with a laser beam so that metal X atoms diffuse into the outer surface to form a modified surface layer of both M and metal X atoms. The bulk portion does not receive the metal X and is generally unaffected by processing, remaining as only M. The modified surface layer has a thickness of at least 1 nanometer and provides a more electrically resistive surface (=2.5 percent higher) than M. The change reduces the ability of rapidly varying magnetic fields to create eddy currents in the medical component.
Partnering Opportunity: The research team is seeking partners for licensing, research collaboration, or both.
