Kimisuke Shirae

New Approach to Noninvasive Manometry Based on Pressure Dependent Resonant Shift of Elastic Microcapsules in Ultrasonic Frequency Characteristics

To measure physiological pressure in situ, we have developed a new technique based on the principle that an elastic microcapsule in liquid changes its resonant frequency depending on the surrounding pressure. The following results were ohtained: 1) The frequency characteristics of transmission wave through microcapsules showed marked attenuation with a specific spectral peak, indicating the resonance of the microcapsules. 2) Pressure dependent change in amplitude of the attenuation peak increased linearly with the increment of pressure. 3) Pressure dependent resonant shifts were also observed in proportion to the pressure increment.

Multichannel DC SQUID System

A new essential multichannel dc SQUID system has been devised. The system consists of two stages of dc SQUIDs; in the first stage, a number of dc SQUIDs equivalent to the input number detect the input signals, and the sum of the first-stage output modulates the carrier of the second-stage dc SQUID and is sent by the carrier to a room temperature amplifier, where the mixed input signals are separated into the original signals. To verify the system operation, a three channel dc SQUID system has been developed and good results have been obtained.

A new multi-element rf SQUID system and its application to the magnetic vector gradiometer

Abstract A multi-element, rf SQUID system is presented, which has many rf SQUID elements coupled to a single rf resonant circuit and only one rf amplifier. The input signal flux applied to every rf SQUID element can be measured separately and simultaneously. Therefore, this new system is very simple and inexpensive compared with conventional ones. As an application of this new system, a vector gradiometer has been developed for the measurement of the three dimensional components of a weak magnetic field.

Dynamic Pressure Measurement Using Two-Frequency Ultrasound

To perform non-invasive pressure measurement by ultrasound, we examined the acoustic characteristics of microcapsules which are dependent on the surrounding pressure. The linear amplitude change of frequency spectrum by pressure was used to develop a fast pressure measurement method. To determine the correspondence of the spectrum amplitude with pressure, we defined a twin frequency attenuation ratio (TAR) as a new pressure parameter measured by two-frequency ultrasound. Dynamic change of pressure was experimentally detected by TAR, whose sensitivity for ultrasonic pressure measurement was thus indicated.

Pressure Measurement Using Ultrasonic Resonance of Microcapsules

This paper describes non-invasive pressure measurement using ultrasonics. We used the method to examine the acoustic characteristics of elastic microcapsules which are dependent on the surrounding pressure with the following results: 1) The frequency characteristics of a transmission wave passing through elastic microcapsules are linearly related to the pressure. 2) The resonance frequency of elastic microcapsules depends on the material. We are therefore able to obtain the pressure by measuring certain acoustic parameters.

Preparation and Properties of (NiZn)Fe2O4 Film by RF Reactive Sputtering

A reactive rf-sputtering method is used for depositing polycrystalline (NiZn)Fe2O4 films. The relations between the magnetic properties of the ferrite films and the sputtering conditions are examined in detail. The best condition of rf-sputtering, under which the magnetization of the films as well as the bulks is obtained and the initial relative permeabilities amount to 50~100 even in the frequency region over the Snoeks limit, is found. Finally, the way to improve the preparation of the films is discussed.

A new superconducting gradiometer complex for vector detection of weak magnetic field

We have devised a superconducting gradiometer complex which enables the second-derivative detection of the vector components of the magnetic field at a point. Consisting of the orthogonal pairs of parallel first-derivative gradiometers, the gradiometer complex detects only two components of the magnetic field at its center, and synthesizes the last component using the former results.

DC SQUID with variable thickness bridge

Abstract We tried to fabricate do SQUID with variable thickness bridge (VTB), instead of the tunnel junction type do SQUIDS. Bridge was realized on a clean surface of substrate by double oblique depositions of Nb in a simple process. VTB type dc SQUIDS work well in our multichannel SQUID system.

An instantaneous echography by ultrasonic fan beam

A new ultrasonic imaging method to obtain an instantaneous echogram is described. This method is developed to detect the object image without scanning by a pulsed fan beam. The experiments are made on copper wires, a vinyl sheet and a sponge in a water vessel. The results show that spot objects can be detected by this method and that projecting multipulse at high frequency and lengthening aperture are effective to improve the image of a plane object and a voluminous object.

The flow mapping method using color Doppler device

A method for displaying a 2-D intracardiac blood flow vector is presented. The flow velocity along the beam is measured by a color Doppler device, and the 2-D velocity vector is estimated by a method based on the continuity equation in flow mechanics. The experimental results show that the system is effective for determining the intracardiac blood flow state.<<ETX>>