SU1690749A1 - Device for transmitting a signal to the implantable portion of an artificial ear - Google Patents

Abstract

The invention relates to medical technology and can be used to create a cochlear prosthetic apparatus. The purpose of the invention is to improve the noise immunity. The device contains the receiving and transmitting electrodes (3) 8 and 1. The E 8 is connected to the demodulator 11. The generator 4 through the acoustic modulator 5 and the balancing amplifier 6 is connected to the E 1. A new device is the execution of E 1 and 8 in the form of identical two-cavity resonators on coupled radial spirals with opposite winding direction, 4 sludge.

Description

The invention relates to medical technology and can be used to create a cochlear prosthetic apparatus.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 - electrode structure; in fig. 3 - variants of the mutual arrangement of the spirals of the resonators; in fig. 4 is a graph of experimental dependencies of the power ratio P in the receiving electrode to the power P0 in the transmitting electrode as a function of frequency.

The device contains a transmitting electrode 1, which represents a resonator on coupled radial spirals 2, 3 with the opposite winding direction, a generator of 4 high-frequency oscillations, a transducer 5 of acoustic oscillations into a modulated electrical signal, a balancing amplifier 6

and a receiving electrode 8, implanted under the skin 7, consisting of two spirals 9, 10, identical to the transmitting electrode 1 and connected by a demodulator 11. The transmitting electrode 1 includes a dielectric (for example, from a signal) plate 12, on both surfaces of which by spraying subsequent galvanic building caused coaxially arranged radial spirals 2, 3 with the opposite direction of winding. Spirals 2, 3 form a quarter-wave resonator with open internal ends 13, 14, and a half-wave resonator with closed internal ends 13, 14 of spirals 2. 3. External ends of 15, 16 spirals 2, 3 are connected to a balancing amplifier 6. In the receiving electrode 8 are internal the ends of the spirals 9. 10 can be open

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or closed, and the outer ends are connected to the demodulator 11.

The proposed device works as follows.

Electromagnetic oscillations are fed from the high-frequency generator 4 to the acoustic modulator 5, which generates the pulses necessary for further decryption of speech. Then, the modulated high-frequency signal is fed to the input of a balancing amplifier 6, the output of which is fed to the input of the transmitting electrode 1 formed by the spirals 2, 3. At frequencies close to resonant, energy is accumulated and the amplitude of the field in the transmitting electrode 1 increases. the field excites currents in the spirals 9, 10 of the receiving electrode 8. Since the spirals 9. 10 have opposite winding directions, the currents induced in them excite an antiphase wave, whose properties are similar to the properties of the wave in the transmitting electrode 1. With the identical geometry of the conductors of the electrodes 1.8, their own resonant frequencies are the same, therefore, a resonant connection arises between the parallel-installed electrodes 1, 8, which is of a band nature. Due to the fact that the area of localization of the field near the surface of the electrodes 1, 8 is limited to 1/6 of the slow wavelength Az, then when choosing a sufficiently large distance between the electrodes 1, 8, the connection will be only on the lower passbands, which reduces the effect interference. Since the radius of the electrodes 1.8, depending on the operating modes (short circuit or idling) in the first passband is placed Az / 2 or Az / 4, the connection between the electrodes 1, 8 in the lower passbands is provided at distances x between the electrodes 1, 8 smaller, respectively, R / 3 and 2R / 3, where R is the external radius of the spirals 2, 3 and 9, 10, the wave excited in the receiving electrode 8 arrives at the input of the demodulator 11 and is converted into an electrical pulse supplied on the cochlea of the inner ear (not shown),

Due to the opposite direction of the winding of the coils in the electrodes 1, 8 and the small distance between them (to ensure effective communication between the coils, this distance should be less than the pitch of the helix) the magnetic fields, creating the azimuthal components of the currents, add up and the inductance increases, which leads to a slowdown of the antiphase electromagnetic wave on

one, two orders of magnitude greater than geometric retardation. By geometric deceleration is meant the ratio of the length of a spiral conductor to its radial size. The increase in deceleration provides the possibility of a resonant mode of the electrode of relatively small size (10-20 mm) at frequencies of 50-70 MHz.

In the spiral mode, the waves of the electric and magnetic types simultaneously exist. With antiphase excitation of an electromagnetic field in spirals with opposite winding directions, the electric-type wave energy is concentrated between the spirals, and the magnetic-type wave energy outside the spirals.

The increase in the efficiency of information and energy transfer is due to the almost complete absence of the effect of the skin on the energy transfer rate. This is due to the inductive coupling between the electrodes 1, 8 and the relatively small distance between them. Interference immunity is provided not only by suppressing higher frequency bandwidths, but also by not being able to excite the antiphase wave in closely spaced spirals with a random signal.

FIG. 4 shows a plot of the ratio of the power P in the receiving electrode to the power Po in the transmitting electrode as a function of the frequency f. From the graph it can be seen that with the distance between the electrodes of 10 mm, the power attenuation is 3 dB, and the bandwidth is 10%, which is more than enough for high-quality transmission of microsecond pulses.

Thus, the signal transmission device in the implantable part of the artificial ear is characterized by noise immunity and high transmission efficiency.

Claims (1)

Invention Formula A device for transmitting a signal to an implantable part of an artificial ear, containing a receiving electrode implanted under the skin, connected to a demodulator, and a transmitting electrode placed opposite to it on the outer surface of the skin, connected to an acoustic signal to an electrical signal sequentially connected and a high-frequency generator, that, in order to increase the noise immunity, the receiving and transmitting electrodes contain a dielectric plate, on both surfaces of which coaxially connected radial current-conducting spirals with the opposite winding direction are present, the ends of the receiving and transmitting electrodes made in the form of two-way strip resonators are connected to a demodulator and an acoustic oscillator into an electrical signal, respectively. Juni fi & 1 % g.H. WtffoЈ & y Pffx J l ten thirty 5070 FIA 100 120 I mgu