NASA Tech Briefs Index, 1977, volume 2, numbers 1-4

Announcements of new technology derived from the research and development activities of NASA are presented. Abstracts, and indexes for subject, personal author, originating center, and Tech Brief number are presented for 1977

Adaptive, High-Resolution Ultrasound Phased Array Imaging for use in the Inspection of Laser Brazed Joints in the Automotive Sector

The inspection of welded and brazed joints has been performed in several industries using ultrasonic phased array. In the automotive sector, many of the current standards for brazed joint inspection do not apply due to the high variations in surface geometry and limited accessibility to the inspection region. As the automotive industry looks to integrate laser brazing into the production process, the need to determine the size and geometry of the joint, as well as the presence of any defects, is desirable to ensure product quality and reduce costs. Currently, the use of destructive techniques, such as cross-sectioning, is employed in the inspection process, with the ultimate desire being the shift to non-destructive methods. With this in mind, ultrasonic techniques have been investigated as a possible testing method. Ultrasound techniques have evolved over the decades, starting from a single element and eventually moving to phased array techniques. Recently, the investigation of the full matrix capture method has become popular in the field of ultrasound imaging. This technique, which separates the data acquisition process from the image formation process poses a viable solution to the inspection of laser brazed joints due to the ability to compensate for varying surfaces in post-processing.In this work, we make use of this technique, deriving the image formation process as an inverse problem for an arbitrary set of ultrasonic emitters and receivers. From this, the image formation process becomes equivalent to solving the inhomogeneous Helmholtz equation. By approximating the solutions to such an equation using the ray series expansion, an estimation of the solutions can be found in a time-efficient manner. When these solutions are found, the inverse process can be rewritten as a weighted, time-delayed summation of the acquired ultrasonic data. In current work, further approximations to this image formation process are often made; however, in the inspection of the laser braze process, these approximations are found to degrade image quality in a number of cases. In this work, we propose our second order corrections as a viable solution to increase the limit under which ultrasound imaging can currently occur. This is accomplished through the design of an ultrasonic array transducer and the manufacturing of a series of simulated defects, with the final assessment being performed on real joints.These techniques were found to improve imaging in a select set of samples when the radius of curvature dropped below 2 mm. In these cases, the use of the amplitude weighting was found to drastically improve system resolution, allowing for the determination of joint size, geometry and the presence of defects

Development of an image converter of radical design

A long term investigation of thin film sensors, monolithic photo-field effect transistors, and epitaxially diffused phototransistors and photodiodes to meet requirements to produce acceptable all solid state, electronically scanned imaging system, led to the production of an advanced engineering model camera which employs a 200,000 element phototransistor array (organized in a matrix of 400 rows by 500 columns) to secure resolution comparable to commercial television. The full investigation is described for the period July 1962 through July 1972, and covers the following broad topics in detail: (1) sensor monoliths; (2) fabrication technology; (3) functional theory; (4) system methodology; and (5) deployment profile. A summary of the work and conclusions are given, along with extensive schematic diagrams of the final solid state imaging system product

Manufacturing and characterisation of a fibre optic acoustic emission sensor

The value of Remote Condition Monitoring for the real-time evaluation of the structural integrity of critical components is undeniable. Fibre-reinforced polymer composites are a class of materials which offer significant advantages over conventional metal alloys used for manufacturing load bearing structures in cases where weight and/or energy consumption need to be kept to a minimum, for example automotive and aerospace applications. This is due to the excellent strength to weight ratio that FRPCs exhibit. However, their strongly anisotropic microstructure of poses significant challenges for Non-Destructive Evaluation of the actual structural health of components made from such materials. Acoustic Emission is a passive condition monitoring technique based on the detection of elastic stress waves emitted when damage evolves in a structure. Conventional piezoelectric AE sensors need to be surface-mounted as their embedding in FRPCs is impractical. Fibre Optic Acoustic Emission Sensors (FOAES) offer a distinct advantage since they are light weight, have small size and can be effectively embedded in composite laminates. Moreover, they can be multiplexed with the entire structure being monitored more effectively. This study has focused in the evaluation of the manufacturing process and characterisation of FOAES. Comparison of their performance with conventional commercial sensors was carried out

Novel planar photonic antennas to address the dynamic nanoarchitecture of biological membranes

The cell membrane is the encompassing protective shield of every cell and it is composed of a multitude of proteins, lipids and other molecules. The organization of the cell membrane is inextricably intertwined with its function, and sensitive to perturbations from the underlying actin cytoskeleton and the extracellular environment at the nano- and the mesoscale. Elucidating the dynamic interplay between lipids and proteins diffusing on the cell membrane, forming transient domains and (re)organizing them according to signals from the juxtaposed inner and outer meshwork, is of paramount interest in fundamental cell biology. The overarching goal of this thesis is to gain deeper insight into how lipids and proteins dynamically organize in biological membranes at the nanoscale. Photonic nano-antennas are metallic nanostructures that localize and enhance the incident optical radiation into highly confined nanometric regions (< 20 nm), leading to greatly enhanced light-matter interactions. In this thesis, we exploit an innovative design of planar gold nano-antenna arrays of different gap sizes (10-45 nm) and embedded in nanometric-size boxes. To elucidate nanoscale diffusion dynamics in biological membranes with high spatiotemporal resolution and single-molecule detection sensitivity, we further combine our nanogap antenna arrays with fluorescence correlation spectroscopy (FCS) in a serial and multiplexed manner. In this dissertation, we first describe the fabrication process of these planar gold nanogap antennas and characterize their performance by means of electron microscopy and FCS of individual molecules in solution. We demonstrate giant fluorescence enhancement factors of up to 104-105 times provided by our planar nanogap antennas in ultra-confined detection volumes and with single molecule detection sensitivity in the micromolar range. Second, we apply these planar plasmonic nano-antennas in combination with FCS for assessing the dynamic organization of mimetic lipid membranes at the nanoscale. For a ternary composition of the model membranes that include unsaturated and saturated lipids together with cholesterol, we resolve transient nanoscopic heterogeneities as small as 10 nm in size, coexisting in both macroscopically phase-separated lipid phases. Third, we add a Hyaluronic Acid (HA) layer on top of the model lipid membranes to emulate the effect of the extracellular environment surrounding native biological membranes. We extend our nano-antenna-FCS approach with atomic force microscopy and spectroscopy. We reveal a distinct influence of HA on the nanoscale lipid organization of mimetic membranes composed of lipids constituting the more ordered lipid phase. Our results indicate a synergistic effect of cholesterol and HA re-organizing biological membranes at the nanoscale. Fourth, we apply our planar nano-antenna platform combined with FCS to elucidate the nanoscale dynamics of different lipids in living cells. With our nanogap antennas we were able to breach into the sub-30 nm spatial scale on living cell membranes for the first time. We provide compelling evidence of short-lived cholesterol-induced ~10 nm nanodomain partitioning in living plasma membranes. Fifth, we demonstrate the multiplexing capabilities of our planar gold nanogap antenna platform combined with FCS in a widefield illumination scheme combined with sCMOS camera detection. Our approach allows recording of fluorescence signal from more than 200 antennas simultaneously. Moreover, we demonstrate multiplexed FCS recording on 50 nano-antennas simultaneously, both in solution as well as in living cells, with a temporal resolution in the millisecond range. The dissertation finishes with a brief discussion of the main results achieved in this research and proposes new avenues for future research in the field.La membrana plasmática separa el entorno intracelular del extracelular y está compuesta por una multitud de diferentes proteínas y lípidos. Su organización está fuertemente interconectada a su función, y es sensible a perturbaciones tanto de la actina cortical posicionada internamente en proximidad con la membrana, así como de una red extracelular en contacto próximo con la membrana exterior. Estas perturbaciones ocurren a distintas escalas temporales y espaciales, llegando a unos pocos nanómetros. Dada la estrecha relación entre la organización de la membrana y su función biológica, es tremendamente importante entender como lípidos y proteínas se organizan dinámicamente a la escala nanométrica y como se ven afectados por su entorno. El objetivo principal de esta tesis doctoral se centra en alcanzar este entendimiento. Las antenas fotónicas son nano-estructuras metálicas que incrementan la radiación electromagnética en regiones nanométricas (< 20 nm) del espacio. En esta tesis doctoral, hemos fabricado y utilizado plataformas con matrices de antenas en oro, y con regiones de confinamiento entre 10-45 nm. Además, hemos combinado estas antenas con la técnica de ¿fluorescence correlation spectroscopy (FCS)¿ a fin de obtener información espaciotemporal a la nano-escala en membranas biológicas, junto a la sensibilidad de detectar moléculas individuales a altas concentraciones. En esta disertación, describimos primero la fabricación de antenas fotónicas y caracterizamos su rendimiento utilizando técnicas de microscopía electrónica y FCS de moléculas individuales en solución. Nuestros resultados demuestran factores de incremento de la fluorescencia entre 104-105, en regiones ultra-confinadas, y una capacidad para detectar moléculas individuales en rango de concentraciones de micro-molares. Una vez validadas nuestras herramientas, nos enfocamos en su uso para el estudio dinámico de la organización de membranas lipídicas miméticas a escala nanométrica. En el caso de composiciones ternarias de lípidos insaturados, saturados y colesterol, hemos descubierto la existencia de heterogeneidades nanoscópicas y transitorias que coexisten tanto en las regiones ordenadas como desordenadas de las membranas lipídicas. El siguiente capítulo contiene resultados enfocados a estudiar el efecto del entorno extracelular en la organización dinámica de este tipo de capas lipídicas. Para ello, y como modelo, preparamos membranas lipídicas cubiertas de ácido hialurónico (HA), un componente abundantemente expresado en la matriz extracelular. Combinando FCS con microscopia y espectroscopia de fuerzas atómicas, logramos resolver la influencia de HA a escala nanométrica en la organización de la fase ordenada de las membranas lipídicas. Nuestros resultados indican la existencia de un efecto sinérgico entre HA y colesterol en el reordenamiento de la membrana a la nano-escala. El siguiente tema de investigación en esta tesis doctoral se enfoca a la aplicación de antenas fotónicas y FCS para el estudio de dominios lipídicos enriquecidos de colesterol en la membrana plasmática de células vivas. La utilización de estas antenas nos ha permitido, por primera vez, remontar la barrera de 30 nm, y demostrar de manera inequívoca la existencia de dominios enriquecidos en colesterol en células vivas con una resolución espacial de 10 nm. Finalmente, hemos demostrado la capacidad de multiplexado de nuestras antenas fotónicas, combinando una iluminación y detección en campo amplio utilizando una camera sCMOS. Describimos la implementación de nuestro esquema, así como también medidas que demuestran la detección simultánea de fluorescencia en más de 200 antenas. De manera importante, demostramos la obtención de curvas de FCS en 50 antenas simultáneamente, tanto en solución como en células vivas. Esta disertación culmina con una breve discusión de los resultados más importantes de esta investigación en el futur

MICROFLUIDICS INTERFACING TO MASS SPECTROMETRY

Polymer-based microfluidic systems have received considerable attention for high throughput chemical analysis. Recently, the ongoing development of microfluidics interfacing to high-accuracy mass spectrometry to identify large molecules had an important impact on biochemistry. A primary goal of this dissertation is the development of a microfluidic apparatus for performing microscale gel electrophoresis, coupled with integrated electrospray tips for either direct interfacing to mass spectrometry through ESI-MS, or coupling to MALDI-MS through the deposition of separated analyte onto a MALDI target for offline analysis. In this dissertation, microfabrication techniques for polymer-based microchip are developed. A novel electrospray interface is demonstrated with good performance. The optimization of multi-channel electrospray tips for multiplexed analysis from a single microfluidic chip was demonstrated. Gas-phased electrophoretic protein/peptide concentration on a pre-structured MALDI target was further demonstrated via theoretical and experimental analysis. The results for developing μGE-ES using linear polymer gel validate the underlined principles and specify challenges involved in coupling μGE to MS. Finally, cross-linked polyacrylamide gel was explored and characterized using in-situ photo- polymerization method in microchannels

CALIBRATION OF AN ULTRASONIC TRANSMISSIVE COMPUTED TOMOGRAPHY SYSTEM

Tato dizertace je zaměřena na medicínskou zobrazovací modalitu – ultrazvukovou počítačovou tomografii – a algoritmy zlepšující kvalitu zobrazení, zejména kalibraci USCT přístroje. USCT je novou modalitou kombinující ultrazvukový přenos signálů a principy tomografické rekonstrukce obrazů vyvíjených pro jiné tomografické systémy. V principu lze vytvořit kvantitativní 3D obrazové objemy s vysokým rozlišením a kontrastem. USCT je primárně určeno pro diagnózu rakoviny prsu. Autor spolupracoval na projektu Institutu Zpracování dat a Elektroniky, Forschungszentrum Karlsruhe, kde je USCT systém vyvíjen. Jeden ze zásadních problémů prototypu USCT v Karlsruhe byla absence kalibrace. Tisíce ultrazvukových měničů se liší v citlivosti, směrovosti a frekvenční odezvě. Tyto parametry jsou navíc proměnné v čase. Další a mnohem závažnější problém byl v pozičních odchylkách jednotlivých měničů. Všechny tyto aspekty mají vliv na konečnou kvalitu rekonstruovaných obrazů. Problém kalibrace si autor zvolil jako hlavní téma dizertace. Tato dizertace popisuje nové metody v oblastech rekonstrukce útlumových obrazů, kalibrace citlivosti měničů a zejména geometrická kalibrace pozic měničů. Tyto metody byly implementovány a otestovány na reálných datech pocházejících z prototypu USCT z Karlsruhe.This dissertation is centered on a medical imaging modality – the ultrasonic computed tomography (USCT) – and algorithms which improve the resulting image quality, namely the calibration of a USCT device. The USCT is a novel imaging modality which combines the phenomenon of ultrasound and image reconstruction principles developed for other tomographic systems. It is capable of producing quantitative 3D image volumes with high resolution and tissue contrast and is primarily aimed at breast cancer diagnosis. The author was involved in a joint research project at the Institute of Data Processing and Electronics, Forschungszentrum Karlsruhe (German National Research Center), where a USCT system is being developed. One of the main problems in the Karlsruhe USCT prototype was the absence of any calibration. The thousands of transducers used in the system have deviations in sensitivity, directivity, and frequency response. These parameters change over time as the transducers age. Also the mechanical positioning of the transducer elements is not precise. All these aspects greatly affect the overall quality of the reconstructed images. The problem of calibration of a USCT system was chosen as the main topic for this dissertation. The dissertation thesis presents novel methods in the area of reconstruction of attenuation images, sensitivity calibration, and mainly geometrical calibration. The methods were implemented and tested on real data generated by the Karlsruhe USCT device.

Extraction of anthropological data with ultrasound

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University.Human body scanners used to extract anthropological data have a significant drawback, the subject is required to undress or wear tight fitting clothing. This thesis demonstrates an ultrasonic based alternative to the current optical systems, that can potentially operate on a fully clothed subject. To validate the concept several experiments were performed to determine the acoustic properties of multiple garments. The results indicated that such an approach was possible. Beamforming is introduced as a method by which the ultrasonic scanning area can be increased, the concept is thoroughly studied and a clear theoretical analysis is performed. Additionally, Matlab has been used to demonstrate graphically, the results of such analysis, providing an invaluable tool during the simulation, experimental and results stages of the thesis. To evaluate beamfoming as a composite part of ultrasonic body imaging, a hardware solution was necessary. During the concept phase, both FPGA and digital signal processors were evaluated to determine their suitability for the role. An FPGA approach was finally chosen, which allows highly parallel operation, essential to the high acquisition speeds required by some beamforming methodologies. In addition, analogue circuitry was also designed to provide an interface with the ultrasonic transducers, which, included variable gain amplifiers, charge amplifiers and signal conditioning. Finally, a digital acquisition card was used to transfer data between the FPGA and a desktop computer, on which, the sampled data was processed and displayed in a coherent graphical manner. The beamforming results clearly demonstrate that imaging multiple layers in air, with ultrasound, is a viable technique for anthroplogical data collection. Furthermore, a wavelet based method of improving the axial resolution is also proposed and demonstrated