Measuring activation patterns of the heart at a microscopic size scale with thin-film sensors

1994 ◽  
Vol 266 (5) ◽  
pp. H2136-H2145 ◽  
Author(s):  
E. Hofer ◽  
G. Urban ◽  
M. S. Spach ◽  
I. Schafferhofer ◽  
G. Mohr ◽  
...  
Keyword(s):  
Thin Film ◽  
High Resolution ◽  
Data Acquisition ◽  
Three Dimensional ◽  
Electrode Array ◽  
Activation Patterns ◽  
Thin Film Sensors ◽  
Amplitude Resolution ◽  
Spread Of Excitation ◽  
Database Program

To study the spread of excitation in ventricular heart preparations we have designed a fast, high-resolution recording and mapping system. Papillary muscles were dissected from the isolated guinea pig hearts. The preparation was fixed in a tissue bath and superfused with Tyrode solution. Linear and two-dimensional arrays of Ag/AgCl electrodes were made on glass with a thin-film technique. The transparent sensors with up to 24 electrodes (spaced 50, 90, or 180 microns apart) were positioned close to the surface of the preparation with a custom-designed three-dimensional micromanipulator. Extracellular signals were simultaneously recorded by a 24-channel data acquisition system with a 200 kHz per channel sample rate, with 12-bit amplitude resolution and a maximum data length of up to 3 MB. Digitized video images of the electrode array and the underlaying preparation were used to identify the locations of the recording sites. A UNIX-based computer system with a custom-designed data acquisition and database program was used to control the instruments and to manage the experimental data. This technique gave signals with excellent signal-to-noise ratios (up to 65 dB) and permitted accurate evaluation of the time and the site of the local activation with high resolution (to within 5 microseconds, 50 microns). We describe the spread of excitation within the area of a few cells and found a substantial dispersion of conduction velocities. Beat-to-beat comparison of activation patterns showed relatively small variations in the spread of excitation (a few microseconds).

Modular Data Acquisition Architecture for Thin-Film Sensors Surfaces

2020 ◽  
Author(s):  
Nelson Rodrigues ◽  
Jose Lima ◽  
Pedro Joao Rodrigues ◽  
Jose Augusto Carvalho ◽  
Jorge Laranjeira ◽  
...  
Keyword(s):  
Thin Film ◽  
Data Acquisition ◽  
Thin Film Sensors ◽  
Modular Data

A Thin-Film Probe for the Measurement of a Three-Dimensional Velocity Vector

1978 ◽  
Vol 20 (6) ◽  
pp. 327-333
Author(s):  
J. K. Aggarwal ◽  
B. J. Bellhouse
Keyword(s):  
Thin Film ◽  
Boundary Layer ◽  
Data Acquisition ◽  
Water Flow ◽  
Velocity Vector ◽  
Three Dimensional ◽  
Boundary Layer Theory ◽  
Water Tank ◽  
Hot Film ◽  
Steady Velocity

A new hot-film probe intended for the measurement of velocity, in magnitude and direction, in three-dimensional water flow is described. Using boundary layer theory, the response of the probe to steady velocity is derived and is found to agree closely with calibrations. The probe has proved to be robust and durable; it produced reliable and repeatable calibrations when towed in a water tank. The method of data acquisition and the technique used for computing the velocity vector are reported.

High Resolution Microscopy of Multi-Layered Biological Crystals

1982 ◽  
Vol 40 ◽  
pp. 80-83
Author(s):  
H.A. Cohen ◽  
T.W. Jeng ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Low Dose ◽  
Three Dimensional ◽  
Data Interpretation ◽  
Two Dimensional ◽  
Biological Objects ◽  
Density Maps ◽  
Density Map ◽  
Complex Crystal ◽  
High Resolution Microscopy

This tutorial will discuss the methodology of low dose electron diffraction and imaging of crystalline biological objects, the problems of data interpretation for two-dimensional projected density maps of glucose embedded protein crystals, the factors to be considered in combining tilt data from three-dimensional crystals, and finally, the prospects of achieving a high resolution three-dimensional density map of a biological crystal. This methodology will be illustrated using two proteins under investigation in our laboratory, the T4 DNA helix destabilizing protein gp32*I and the crotoxin complex crystal.

Imaging of platinum-shadowed macromolecular complexes in dark field

1984 ◽  
Vol 42 ◽  
pp. 146-147
Author(s):  
D.W. Andrews ◽  
F.P. Ottensmeyer
Keyword(s):  
Thin Film ◽  
Three Dimensional ◽  
Average Diameter ◽  
Dark Field ◽  
Bright Field ◽  
Field Mode ◽  
Macromolecular Complexes ◽  
Average Mass ◽  
Topological Features ◽  
Projection Images

Shadowing with heavy metals has been used for many years to enhance the topological features of biological macromolecular complexes. The three dimensional features present in directionaly shadowed specimens often simplifies interpretation of projection images provided by other techniques. One difficulty with the method is the relatively large amount of metal used to achieve sufficient contrast in bright field images. Thick shadow films are undesirable because they decrease resolution due to an increased tendency for microcrystalline aggregates to form, because decoration artefacts become more severe and increased cap thickness makes estimation of dimensions more uncertain.The large increase in contrast provided by the dark field mode of imaging allows the use of shadow replicas with a much lower average mass thickness. To form the images in Fig. 1, latex spheres of 0.087 μ average diameter were unidirectionally shadowed with platinum carbon (Pt-C) and a thin film of carbon was indirectly evaporated on the specimen as a support.

Electron crystallographic determination of the 3-D structure of staurolite at atomic resolution

1991 ◽  
Vol 49 ◽  
pp. 540-541
Author(s):  
Kenneth H. Downing ◽  
Hu Meisheng ◽  
Hans-Rudolf Went ◽  
Michael A. O'Keefe
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
High Resolution Electron Microscopy ◽  
Atomic Resolution ◽  
Dimensional Structure ◽  
Structure Information ◽  
Resolution Electron ◽  
Scattering Effects ◽  
High Resolution Images ◽  
Effects Of Radiation

With current advances in electron microscope design, high resolution electron microscopy has become routine, and point resolutions of better than 2Å have been obtained in images of many inorganic crystals. Although this resolution is sufficient to resolve interatomic spacings, interpretation generally requires comparison of experimental images with calculations. Since the images are two-dimensional representations of projections of the full three-dimensional structure, information is invariably lost in the overlapping images of atoms at various heights. The technique of electron crystallography, in which information from several views of a crystal is combined, has been developed to obtain three-dimensional information on proteins. The resolution in images of proteins is severely limited by effects of radiation damage. In principle, atomic-resolution, 3D reconstructions should be obtainable from specimens that are resistant to damage. The most serious problem would appear to be in obtaining high-resolution images from areas that are thin enough that dynamical scattering effects can be ignored.

Three-Dimensional Immunoelectron Microscopy of Yeast Cells by a New High-Resolution Replica Method

1985 ◽  
Vol 43 ◽  
pp. 562-563
Author(s):  
Hirano T. ◽  
M. Yamaguchi ◽  
M. Hayashi ◽  
Y. Sekiguchi ◽  
A. Tanaka
Keyword(s):  
High Resolution ◽  
Plasma Polymerization ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Replica Method ◽  
Yeast Cells ◽  
Dynamic Aspect ◽  
Replica Technique ◽  
Gaseous Hydrocarbon ◽  
Transmission Electron

A plasma polymerization film replica method is a new high resolution replica technique devised by Tanaka et al. in 1978. It has been developed for investigation of the three dimensional ultrastructure in biological or nonbiological specimens with the transmission electron microscope. This method is based on direct observation of the single-stage replica film, which was obtained by directly coating on the specimen surface. A plasma polymerization film was deposited by gaseous hydrocarbon monomer in a glow discharge.The present study further developed the freeze fracture method by means of a plasma polymerization film produces a three dimensional replica of chemically untreated cells and provides a clear evidence of fine structure of the yeast plasma membrane, especially the dynamic aspect of the structure of invagination (Figure 1).

The measurement of thin-film reaction layers with high-resolution FESEM

1995 ◽  
Vol 53 ◽  
pp. 330-331
Author(s):  
Paul G. Kotula ◽  
C. Barry Carter
Keyword(s):  
Thin Film ◽  
High Resolution ◽  
Reaction Layer ◽  
Product Layer ◽  
Buffer Layers ◽  
Oxide Superconductors ◽  
Rate Limiting Step ◽  
Ceramic Thin Film ◽  
Backscattered Electron ◽  
Boundary Reaction

Thin-film reactions in ceramic systems are of increasing importance as materials such as oxide superconductors and ferroelectrics are applied in thin-film form. In fact, reactions have been found to occur during the growth of YBa2Cu3O6+x on ZrO2. Additionally, thin-film reactions have also been intentionally initiated for the production of buffer layers for the subsequent growth of high-Tc superconductor thin films. The problem is that the kinetics of ceramic thin-film reactions are not well understood when the reaction layer is very thin; that is, when the rate-limiting step is a phase-boundary reaction as opposed to diffusion of the reactants through the product layer. In this case, the reaction layer is likely to be laterally non-uniform. In the present study, the measurement of thin reaction-product layers is accomplished by first digitally acquiring backscattered-electron images in a high-resolution field-emission scanning electron microscope (FESEM) followed by image analysis. Furthermore, the problem of measuring such small thicknesses (e.g., 20-500nm) over lengths of interfaces longer than 3mm is addressed.

High-resolution scanning electron microscopy of thin-film magnetic media of magnetic recording disk

1992 ◽  
Vol 50 (2) ◽  
pp. 1334-1335
Author(s):  
K. Ogura ◽  
H. Nishioka ◽  
N. Ikeo ◽  
T. Kanazawa ◽  
J. Teshima
Keyword(s):  
Thin Film ◽  
Fine Structure ◽  
High Resolution ◽  
Magnetic Recording ◽  
High Performance ◽  
Magnetic Hysteresis ◽  
Grain Structure ◽  
Magnetic Media ◽  
Cross Sectional ◽  
Resolution Observation

Structural appraisal of thin film magnetic media is very important because their magnetic characters such as magnetic hysteresis and recording behaviors are drastically altered by the grain structure of the film. However, in general, the surface of thin film magnetic media of magnetic recording disk which is process completed is protected by several-nm thick sputtered carbon. Therefore, high-resolution observation of a cross-sectional plane of a disk is strongly required to see the fine structure of the thin film magnetic media. Additionally, observation of the top protection film is also very important in this field.Recently, several different process-completed magnetic disks were examined with a UHR-SEM, the JEOL JSM 890, which consisted of a field emission gun and a high-performance immerse lens. The disks were cut into approximately 10-mm squares, the bottom of these pieces were carved into more than half of the total thickness of the disks, and they were bent. There were many cracks on the bent disks. When these disks were observed with the UHR-SEM, it was very difficult to observe the fine structure of thin film magnetic media which appeared on the cracks, because of a very heavy contamination on the observing area.

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