3D laser scanner based on surface silicon micromachining techniques for shape and size reconstruction of the human ear canal

2005/2006As technology advances, hearing aids can be packaged into increasingly smaller housings. Devices that fit entirely within the deeper portion of the external auditory canal have been developed, called completely-in-the-canal (CIC). These aids are custom moulded and have high cosmetic appeal because they are virtually undetectable. They also have several acoustic advantages: reduced occlusion effect, reduced gain requirements, and preservation of the natural acoustic properties of the pinna and external ear. However, CIC hearing aids require proper fitting of the hearing aid shell to the subject ear canal to achieve satisfactory wearing comfort, reduction in acoustic feedback, and unwanted changes in the electro-acoustic characteristics of the aid. To date, the hearing aid shell manufacturing process is fully manual: the shell is fabricated as a replica of the impression of the subject ear canal. Conventional impression acquisition method is very invasive and imprecise, moreover the typical post-impression processes made on the ear impression leaves room for error and may not accurately represent the structural anatomy of patient’s ear canal. There are some laser approaches able to perform a 3D laser scanning of the original ear impression but, the entire shell-making process is completely dependent on the ear impression and often is the sole cause of poor fitting shell. Therefore, direct ear canal scanning is the only way to perform accurate and repeatable measurements without the use of physical ear impression. The conventional optical elements are not able to enter in the inner part of the ear and perform a scanning of the cavity. This work is devoted to the direct scanning of human external auditory canal by using electromagnetically actuated torsion micromirror fabricated by micromachining technique as scanner. This is the first ever demonstration of actual scanning of human external auditory canal by a single integral Micro-Electro-Mechanical System (MEMS). A novel prototype 3D scanning system is developed together with surface reconstruction algorithm to obtain an explicit 3D reconstruction of actual human auditory canal. The system is based on acquisition of optical range data by conoscopic holographic laser interferometer using electromagnetically actuated scanning MEMS micromirror. An innovative fabrication process based on poly(methylmethacrylate) (PMMA) sacrificial layer for fabrication of free standing micromirror is used. Micromirror actuation is achieved by using magnetic field generated with an electromagnetic coil stick. Micromirror and electromagnet coil assembly composes the opto-mechanical scanning probe used for entering in ear auditory canal. Based on actual scan map, a 3D reconstructed digital model of the ear canal was built using a surface point distribution approach. The proposed system allows noninvasive 3D imaging of ear canal with spatial resolution in the 10 μm range. Fabrication of actual shell from in-vivo ear canal scanning is also accomplished. The actual human ear canal measurement techniques presented provide a characterization of the ear canal shape, which help in the design and refining of hearing aids fabrication approaches to patient personalized based.XIX Ciclo197

Development of electrochemical biosensors by e-beam lithography for medical diagnostics

In this work the fabrication and characterization of boron-doped diamond (BDD) nanoelectrode arrays are discussed. The use of boron-doped diamond electrodes is very attractive due to advantageous properties including high reproducibility, stability, and robustness under extreme conditions, where conventional electrode materials may undergo severe erosion. BDD electrodes have also proved to be very useful because they show an extremely wide potential window in aqueous solutions without oxidation of the electrode itself. This allows electrochemical detection, at tiny background currents, of a number of substances that oxidize at very positive potentials, where other electrodic materials are not suitable. BDD based NEAs were prepared using Si substrates coated with a layer of Boron doped diamond as macroelectrode. NEAs were obtained by creating an array of nanoholes by electron beam lithography (EBL) in a thin film of polycarbonate deposited on top of the macroelectrode. This approach leads to the formation of recessed nanoelectrodes. The parameters for using polycarbonate as a novel electron beam resist have been optimized and successfully used for fabrication of NEAs. The most interesting properties of this polymer for nanofabrication purposes are the high lithographic contrast, which allows the creation of structures of dimensions less than 100 nm; chemical stability, which guarantees a long-term use in electrochemical solutions and the possibility of functionalization with biological molecules (DNA and proteins). NEAs have been characterized with cyclic voltammetry and have provided voltammetric signals controlled by pure radial diffusion. The low background current of BDD added to the properties of NEAs indicate that this system can be applied for the development of sensors with high sensitivity. Polycarbonate surface of NEAs was successfully functionalized with small ss-DNA sequence, confirming the possibility of exploiting these systems as diagnostic biosensors

On the Properties of WC/SiC Multilayers

A study of the materials properties of WC/SiC multilayer coatings is presented. We investigated the dependence of interface and surface roughness, intrinsic stress, microstructure, chemical composition, and stoichiometry as a function of multilayer period and in some cases compared these to W/SiC multilayer systems. The WC/SiC material pair forms multilayers with extremely smooth and sharp interfaces and both materials remain amorphous over a wide range of thicknesses. These properties are desirable for multilayer-based high-resolution diffractive x-ray optics, such as multilayer Laue lenses (MLLs), which require very thick films in which the layer spacing varies considerably. Thermal and structural stability studies show that WC/SiC multilayers have exceptional thermal stability, making this an extremely robust and favorable material pair for MLLs and other multilayer-based X-ray optical elements

On the Properties of WC/SiC Multilayers

A study of the materials properties of WC/SiC multilayer coatings is presented. We investigated the dependence of interface and surface roughness, intrinsic stress, microstructure, chemical composition, and stoichiometry as a function of multilayer period and in some cases compared these to W/SiC multilayer systems. The WC/SiC material pair forms multilayers with extremely smooth and sharp interfaces and both materials remain amorphous over a wide range of thicknesses. These properties are desirable for multilayer-based high-resolution diffractive x-ray optics, such as multilayer Laue lenses (MLLs), which require very thick films in which the layer spacing varies considerably. Thermal and structural stability studies show that WC/SiC multilayers have exceptional thermal stability, making this an extremely robust and favorable material pair for MLLs and other multilayer-based X-ray optical elements

On the Properties of WC/SiC Multilayers

A study of the materials properties of WC/SiC multilayer coatings is presented. We investigated the dependence of interface and surface roughness, intrinsic stress, microstructure, chemical composition, and stoichiometry as a function of multilayer period and in some cases compared these to W/SiC multilayer systems. The WC/SiC material pair forms multilayers with extremely smooth and sharp interfaces and both materials remain amorphous over a wide range of thicknesses. These properties are desirable for multilayer-based high-resolution diffractive x-ray optics, such as multilayer Laue lenses (MLLs), which require very thick films in which the layer spacing varies considerably. Thermal and structural stability studies show that WC/SiC multilayers have exceptional thermal stability, making this an extremely robust and favorable material pair for MLLs and other multilayer-based X-ray optical elements

An analysis of X-ray multilayer Laue lenses made by masked deposition

Multilayer Laue lenses are diffractive optics for hard X-rays. To achieve high numerical aperture and resolution, diffracting structures of nanometer periods are required in such lenses, and a thickness (in the direction of propagation) of several micrometers is needed for high diffracting efficiency. Such structures must be oriented to satisfy Bragg’s law, which can only be achieved consistently over the entire lens if the layers vary in their tilt relative to the incident beam. The correct tilt, for a particular wavelength, can be achieved with a very simple technique of using a straight-edge mask to give the necessary gradient of the layers. An analysis of the properties of lenses cut from such a shaded profile is presented and it is shown how to design, prepare, and characterize matched pairs of lenses that operate at a particular wavelength and focal length. It is also shown how to manufacture lenses with ideal curved layers for optimal efficiency

Extended asymmetric-cut multilayer X-ray gratings

he fabrication and characterization of a large-area high-dispersion blazed grating for soft X-rays based on an asymmetric-cut multilayer structure is reported. An asymmetric-cut multilayer structure acts as a perfect blazed grating of high efficiency that exhibits a single diffracted order, as described by dynamical diffraction throughout the depth of the layered structure. The maximum number of grating periods created by cutting a multilayer deposited on a flat substrate is equal to the number of layers deposited, which limits the size of the grating. The size limitation was overcome by depositing the multilayer onto a substrate which itself is a coarse blazed grating and then polish it flat to reveal the uniformly spaced layers of the multilayer. The number of deposited layers required is such that the multilayer thickness exceeds the step height of the substrate structure. The method is demonstrated by fabricating a 27,060 line pairs per mm blazed grating (36.95 nm period) that is repeated every 3,200 periods by the 120-μm period substrate structure. This preparation technique also relaxes the requirements on stress control and interface roughness of the multilayer film. The dispersion and efficiency of the grating is demonstrated for soft X-rays of 13.2 nm wavelength