Optical Coherence Tomography guided Laser-Cochleostomy

Despite the high precision of laser, it remains challenging to control the laser-bone ablation without injuring the underlying critical structures. Providing an axial resolution on micrometre scale, OCT is a promising candidate for imaging microstructures beneath the bone surface and monitoring the ablation process. In this work, a bridge connecting these two technologies is established. A closed-loop control of laser-bone ablation under the monitoring with OCT has been successfully realised

Integrated polymer photonics : fabrication, design, characterization and applications

[no abstract

NASA SBIR abstracts of 1990 phase 1 projects

The research objectives of the 280 projects placed under contract in the National Aeronautics and Space Administration (NASA) 1990 Small Business Innovation Research (SBIR) Phase 1 program are described. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses in response to NASA's 1990 SBIR Phase 1 Program Solicitation. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 280, in order of its appearance in the body of the report. The document also includes Appendixes to provide additional information about the SBIR program and permit cross-reference in the 1990 Phase 1 projects by company name, location by state, principal investigator, NASA field center responsible for management of each project, and NASA contract number

Summary of investigations of light scattering in highly reflecting pigmented coatings

Light scattering in highly reflecting pigmented coatings - silver bromide and particle suspensions and paint film

Tomographic measurement of all orthogonal components of three-dimensional displacement fields within scattering materials using wavelength scanning interferometry

Experimental mechanics is currently contemplating tremendous opportunities of further advancements thanks to a combination of powerful computational techniques and also fullfield non-contact methods to measure displacement and strain fields in a wide variety of materials. Identification techniques, aimed to evaluate material mechanical properties given known loads and measured displacement or strain fields, are bound to benefit from increased data availability (both in density and dimensionality) and efficient inversion methods such as finite element updating (FEU) and the virtual fields method (VFM). They work at their best when provided with dense and multicomponent experimental displacement (or strain) data, i.e. when all orthogonal components of displacements (or all components of the strain tensor) are known at points closely spaced within the volume of the material under study. Although a very challenging requirement, an increasing number of techniques are emerging to provide such data. In this Thesis, a novel wavelength scanning interferometry (WSI) system that provides three dimensional (3-D) displacement fields inside the volume of semi-transparent scattering materials is proposed. Sequences of two-dimensional interferograms are recorded whilst tuning the frequency of a laser at a constant rate. A new approach based on frequency multiplexing is used to encode the interference signal corresponding to multiple illumination directions at different spectral bands. Different optical paths along each illumination direction ensure that the signals corresponding to each sensitivity vector do not overlap in the frequency domain. All the information required to reconstruct the location and the 3-D displacement vector of scattering points within the material is thus recorded simultaneously in a single wavelength scan. By comparing phase data volumes obtained for two successive scans, all orthogonal components of the three dimensional displacement field introduced between scans (e.g. by means of loading or moving the sample under study) are readily obtained with high displacement sensitivity. The fundamental principle that describes the technique is presented in detail, including the correspondence between interference signal frequency and its associated depth within the sample, depth range, depth resolution, transverse resolution and displacement sensitivity. Data processing of the interference signal includes Fourier transformation, noise reduction, re-registration of data volumes, measurement of the illumination and sensitivity vectors from experimental data using a datum surface, phase difference evaluation, 3-D phase unwrapping and 3-D displacement field evaluation. Experiments consisting of controlled rigid body rotations and translations of a phantom were performed to validate the results. Both in-plane and the out-of-plane displacement components were measured for each voxel in the resulting data volume, showing an excellent agreement with the expected 3-D displacement

Index to NASA Tech Briefs, 1975

This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs

X-Ray Interrogated Implantable Chemical and Strain Sensors for Monitoring Implant Associated Infections And Fracture Healing

Bone fracture healing includes complex and sequence of dynamic events to restore the integrity and biomechanical properties of the bone. While most of the fractures heal without any problem, healing is sometimes compromised. Two significant fracture healing complications are orthopedic implant-associated infections and non-unions/delayed union. These can be interrelated causes as well. Implant-associated infection can cause implant loosening, and as a result, it can delay the fracture healing process. Herein, we describe two different types of sensors that can be used in monitoring biochemical and biomechanical processes of fracture healing using X-rays. We developed a XELCI (X-ray Excited Luminescence Chemical Imaging) based biochemical sensor for monitoring implant-associated infections by decreasing pH due to acidic products of bacterial metabolism. High spatial resolution pH mapping of the intramedullary canal through bone and tissue was carried out with the XELCI imaging technique developed in our lab. Pre-pilot rabbit studies were carried out to monitor the pH variations in the intramedullary canal of the rabbit tibia by creating two infected rabbit models compared to a sterile control rabbit. We observed a pH drop in the intramedullary canal while using the pH-sensitive hydrogel-coated intramedullary rod. Moreover, to monitor stiffness and biomechanical properties of the healing bone during fracture healing, we developed a biomechanical sensor with hydromechanical amplification read via plain radiography. The sensor was mounted on Sawbones tibia models (fractured and allograft repaired) and human cadaveric tibia and tested under cyclic loading. The sensor displayed reversible and repeatable behavior with a slope of 0.096 mm/kg and fluid level noise of 50 to 80 micrometer (equivalent to 5-10 N). While both these sensors will address the two major issues in fracture healing providing useful insight, they can be improved with future modifications. The proposed intramedullary rod design with wells can be machined in stainless steel to be a more robust sensor. Moreover, as we carried out this study as a pre-pilot study, we can extend it into a full study also combining it with antibiotic treatment in animal models. Chromoionophore III can be investigated as a potential dye for monitoring pH as well as other analytes of interest at the fracture site. The fluidic sensor can be improved by miniaturizing the sensor components and designing it to attach to the side of the orthopedic implant plate where there’s more room for sensor accommodation. In addition, the sensor can be applied in other types of fractures and implant plates as the senor was only studied on tibial implant plates