JP2008178447A - In vivo device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in vivo device with high radiation characteristics not to be affected by in vivo antenna arrangement without enlarging an in vivo antenna element. <P>SOLUTION: The in vivo device 100 to be arranged inside a living body comprises a monopole element 101 loaded on the in vivo device 100 and a parasitic element 104 arranged outside the living body closely to the monopole element 101. By the configuration, since the monopole element 101 and the passive element 104 are capacitively coupled and the parasitic element 104 is operated as an antenna element, antenna performance is increased. Thus, the monopole element 101 arranged inside the living body is reduced in size and burdens on the living body are reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a device implanted in a living body, and particularly to an antenna of an in-vivo medical device for communicating with an in-vitro device.

  Currently, in-vivo medical devices that are implanted in vivo and perform medical care are placed outside the body to enable transmission of various medical data (for example, an electrocardiogram) regardless of the behavior of the medical staff and the posture of the patient. Development of an in-vivo medical device equipped with a function of communicating with a wireless device has been performed. In the world, regulations for setting the used frequency band to 402 MHz to 405 MHz are being prepared in various countries around the world.

  As an antenna mounted on the in-vivo medical device, for example, as described in Patent Document 1, an antenna configuration in which an RFID tag is mounted on the in-vivo medical device is shown. The RFID tag has a configuration in which an RFID chip and an antenna are mounted on a small substrate of about several millimeters, and the RFID tag is mounted on an in-vivo medical device.

  With this configuration, in-vivo / external communication between an RFID tag in a living body and an interrogator outside the living body becomes possible.

  On the other hand, in general, in-vivo medical devices are rapidly becoming smaller in order to reduce the burden on the patient as much as possible. In order to ensure the performance of the antenna, it is generally only necessary to set the antenna length to half the wavelength. It is required to be. This is as small as about one-tenth of a wavelength of about 750 mm in the 400 MHz band. Therefore, there is a problem that the radiation resistance of the antenna is reduced and the radiation performance is deteriorated (sensitivity is deteriorated). .

  From these backgrounds, as a method for improving the radiation characteristics of an antenna, for example, as described in Patent Document 2, in FIG. 9, the configuration of an antenna in an implantable defibrillator is shown as a conventional in-vivo medical device. It is shown. In FIG. 9, an implantable defibrillator 300 connects one terminal of a pulse generator 306 to an antenna 301 (antenna wire 309, lead wire 102) supported by a resin header 302, and connects the other terminal to a metal. By connecting to the housing 111 at the housing ground point 307, the antenna 301 and the metal housing 111 are operated as electrodes of the pulse generator 306, and the wireless circuit 108 is grounded to the wireless circuit ground 308 instead of the housing ground point 307. The transformer 303 is arranged between the (secondary winding 305 side) and the antenna 301 (primary winding 304 side).

With this configuration, the lead wire 102 (the electrode of the pulse generator 306), which is the largest component in the in-vivo device, can be used as the antenna 301, so that the radiation characteristics of the antenna can be improved.
JP 2006-263468 A US Pat. No. 6,505,072 (FIG. 2)

  However, in the conventional configuration described in Patent Document 1, details of the antenna configuration mounted on the RFID tag in the living body are not described, and the antenna is as small as several millimeters. Because the gain is low and the communication distance is short, it is necessary to bring the interrogator outside the living body closer to the place where the in-vivo medical device is implanted. It is difficult to do. Therefore, there is a problem that it is necessary to enlarge the antenna in order to increase the communication distance.

  Further, in the conventional configuration described in Patent Document 2, since the lead wire is used as an antenna, there are individual differences in the shape and wiring position when implanted in a living body, mismatch loss, antenna gain, etc. As a result, there is a problem that it is difficult to ensure stable antenna performance.

  In order to solve the above-mentioned problems, the present invention can reduce the antenna element in the living body by bringing the parasitic element arranged outside the living body close to the antenna element in the living body. It is an object of the present invention to provide an in-vivo device having high radiation characteristics that are not affected.

  In order to solve the above-described conventional problems, an in-vivo device of the present invention includes an antenna element mounted on an in-vivo device disposed inside the living body, and a parasitic element disposed outside the living body in the vicinity of the antenna element. With.

  With this configuration, the antenna element and the parasitic element are capacitively coupled, and the parasitic element operates as the antenna element, so that the antenna performance can be improved. In addition, this makes it possible to reduce the antenna element disposed in the living body and reduce the burden on the living body.

  The in-vivo device of the present invention includes a first antenna element that is disposed on the in-vivo device and slightly protrudes from the inside of the living body to the surface of the living body, and a second antenna element that is disposed on the surface of the living body. The projecting portion of the second antenna element is connected to the second antenna element.

  With this configuration, the second antenna element is less affected by the deterioration of radiation performance due to the living body, and the antenna performance can be improved. In addition, this makes it possible to reduce the first antenna element disposed in the living body and reduce the burden on the living body.

  In the in-vivo device of the present invention, the parasitic element and the second antenna element are formed of a conductive adhesive sheet having flexibility.

  With this configuration, the parasitic element and the second antenna element can be arranged at predetermined positions on the surface of the living body.

  Moreover, the in-vivo device of the present invention is configured by providing the parasitic element and the second antenna element at predetermined positions of clothing.

  With this configuration, the parasitic element and the second antenna element can be disposed at predetermined positions without bringing an adhesive into contact with the living body.

  The in-vivo device of the present invention is configured by embedding the parasitic element and the second antenna element in the clothing.

  With this configuration, the parasitic element and the second antenna element can be arranged at predetermined positions without bringing an adhesive into contact with the living body, as described above.

  As described above, according to the present invention, an in-vivo device includes an antenna element mounted on an in-vivo device disposed inside a living body, and a parasitic element disposed outside the living body in proximity to the antenna element. Since the antenna element and the parasitic element are capacitively coupled and the parasitic element operates as the antenna element, the antenna performance can be improved. In addition, this makes it possible to reduce the antenna element disposed in the living body and reduce the burden on the living body.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing the state of use of the in-vivo device according to the first embodiment of the present invention, and FIGS. In the description, the operating frequency is set to 400 MHz, for example.

  In FIG. 1, the in-vivo device 100 is disposed inside the human body 1, and the monopole element 101 mounted on the housing 103 of the in-vivo device 100 is disposed at a depth of, for example, about 4 mm from the surface of the human body 1. The lead wire 102 for observing information of the heart 2 (data such as an electrocardiogram) is fixed to the heart 2. The parasitic element 104 is formed of a flexible conductive adhesive sheet, and is disposed in close contact with the surface of the human body 1 adjacent to the monopole element 101. The in-vivo device 100 communicates with the in-vitro device 4 equipped with the in-vitro antenna element 3 to transfer information observed by the lead wire 102 and rewrite the program of the in-vivo device 100.

  In FIG. 2, a resin casing 106 that is a casing of the in-vivo device 100 is made of resin, and is set to have a length of about 50 mm, a width of 50 mm, and a thickness of about 15 mm, for example. The monopole element 101 has, for example, an L-shaped structure with a length of 15 mm and a width of 12 mm, and is connected to the radio circuit 108 via the matching circuit 107. The matching circuit 107 has a function of performing impedance matching between the monopole element 101 and the radio circuit 108. The lead wire 102 is connected to a detection circuit 109 that detects observation data such as an electrocardiogram. The substrate ground 110 is set to 45 mm long and 45 mm wide, for example. The matching circuit 107, the radio circuit 108, and the detection circuit 109 are grounded to the substrate ground 110. The parasitic element 104 is set to a rectangular plate shape having a length of 30 mm, a width of 30 mm, and a thickness of about 1 mm, for example. The center of the element 104 is arranged so as to overlap with the center of the element (12 mm wide) extending in the + Y direction of the monopole element 101. The distance is about (a distance from the surface of the human body 1 shown in FIG. 1 to the monopole element 101).

  The operation of the antenna of the in-vivo device configured as described above will be described. Since the element length of the monopole element 101 is about 27 mm as described above and is as small as 0.04 wavelength compared with the wavelength 750 mm of 400 MHz, the antenna current is distributed not only to the monopole element 101 but also to the substrate ground 110. To do. The monopole element 101 and the substrate ground 110 in which these antenna currents are distributed are capacitively coupled to the parasitic element 104, whereby the excitation current is distributed to the parasitic element 104. Thereby, the parasitic element 104 disposed outside the living body operates as an antenna element capacitively coupled, and the radiation efficiency is improved by 3 dB as compared with the case where the parasitic element 104 is not disposed.

  As described above, according to the first embodiment, the parasitic element 104 is disposed outside the living body in the vicinity of the monopole element 101 disposed in the living body. Since the feed element 104 is capacitively coupled and the parasitic element 104 operates as an antenna element, the antenna performance can be improved. Moreover, the monopole element 101 arrange | positioned in the biological body by this can be made small, and the burden on a biological body can be reduced.

  In the case of a device that applies electrical stimulation to a human body for treatment, such as an implantable cardioverter defibrillator, a metal housing may be used as an electrode. In such a case, as shown in FIG. 3 (the parasitic element 104 is disposed so as not to overlap the metal casing 111), the substrate ground 110 is grounded to the metal casing 111 at the ground point 112, Since the antenna current is distributed in the metal casing 111, the same effect as when the casing is made of resin can be obtained.

  As shown in FIG. 4, the parasitic element 104 is formed in a disk shape having a diameter of about 30 mm and a thickness of about 1 mm without changing the center position. As a result, the radiation efficiency is improved by 4 dB as compared with the case where the parasitic element 104 is not disposed, and is improved by 1 dB as compared with the rectangular plate shape described with reference to FIG. Further, the antenna performance can be further enhanced by increasing the size of the parasitic element 104 so as not to overlap the metal casing 111.

  In addition, since the parasitic element 104 is disposed on the surface of the human body 1, it is desirable that the parasitic element 104 be small. By making the parasitic element 104 into a meander shape, the length of a half wavelength (375 mm) can be secured while keeping the volume constant, so that the radiation efficiency is the same as when the parasitic element 104 is made into a half wavelength without being a meander shape. An effect is obtained.

  In the present embodiment, the parasitic element 104 is composed of a flexible conductive adhesive sheet, but as shown in FIG. 5, in the garment 205 that can be fixedly attached to the human body 1, The parasitic element 104 may be embedded in a predetermined position of the clothing 205 so as to be sandwiched between the clothing back surface 206 and the clothing surface 207. With this configuration, the parasitic element 104 can be disposed at a predetermined position with respect to the human body 1 without bringing the adhesive into contact with the human body 1, and the same effect as the radiation efficiency in the case of the conductive adhesive sheet configuration can be obtained. can get.

  In this embodiment, the antenna mounted on the in-vivo device 100 is the monopole element 101, but a loop antenna, an inverted F antenna, a patch antenna, or the like may be used.

(Embodiment 2)
FIG. 6 is a diagram showing a state of use of the in-vivo device according to the second embodiment of the present invention, FIG. 7 is a configuration diagram of the antenna of the in-vivo device according to the second embodiment of the present invention, and FIG. Fig. 5 shows means for attaching an antenna of an intracorporeal device to a garment. In the following description, the same components as those in FIG. 1 and FIG.

  In FIG. 6, the first antenna element 201 mounted on the housing 103 of the in-vivo device 100 is arranged so as to protrude from the surface of the human body 1 by about 2 mm, for example. The second antenna element 202 is composed of a conductive adhesive sheet having flexibility, and is electrically connected by the protrusions 204 of the first antenna element 201.

  In FIG. 7, the first antenna element 201 has, for example, an L-shaped structure with a length of 15 mm and a width of 12 mm, and is connected to the radio circuit 108 via the matching circuit 107 so that the open end is in the + X direction. For example, the second antenna element 202 is set to have a disk shape with a diameter of about 30 mm and a thickness of about 1 mm, and the open end of the first antenna element 201 and the center of the second antenna element 202 are electrically connected. Two antenna elements 202 are arranged.

  The operation of the antenna of the in-vivo device configured as described above will be described. The antenna current distributed to the first antenna element 201 disposed in the living body is also distributed to the second antenna element 202 disposed outside the living body. As a result, the second antenna element 201 is less affected by deterioration in radiation performance due to the living body, and the radiation efficiency is improved by 9 dB as compared with the case where the second antenna element 202 is not disposed.

  As described above, according to the second embodiment, the second antenna element 201 is configured such that the first antenna element 201 disposed in the living body and the second antenna element 202 disposed outside the living body are electrically connected. The influence of deterioration of radiation performance by the living body is reduced, and the antenna performance can be improved. This also makes it possible to reduce the size of the first antenna element 201 disposed in the living body, thereby reducing the burden on the living body. Further, the antenna performance can be further improved by enlarging the second antenna element 202 without enlarging the first antenna element 201.

  In the present embodiment, the second antenna element 202 is composed of a flexible conductive adhesive sheet, but as shown in FIG. 8, as described in the first embodiment, A hole 208 may be formed in the clothing back surface 206 so as to be embedded in the clothing and to connect the first antenna element 201 and the second antenna element 202.

  As described in the first embodiment, the casing may be a metal casing. The second antenna element 202 may have a meander shape.

  In the in-vivo device of the present invention, the in-vivo device includes an antenna element mounted on the in-vivo device disposed inside the living body, and a parasitic element disposed outside the living body in proximity to the antenna element. Thus, the antenna element and the parasitic element are capacitively coupled, and the parasitic element operates as the antenna element, whereby the antenna performance can be improved. In addition, this makes it possible to reduce the antenna element disposed in the living body and reduce the burden on the living body. Therefore, it is useful as a configuration of an antenna mounted on a pacemaker, an implantable cardioverter defibrillator, or the like.

Usage state diagram of in-vivo device in embodiment 1 of the present invention Antenna configuration diagram of in-vivo device according to Embodiment 1 of the present invention Antenna configuration diagram when the housing of the in-vivo device in Embodiment 1 of the present invention is a metal Antenna configuration diagram when parasitic element of in-vivo device in Embodiment 1 of the present invention is disk-shaped The figure which shows the means which equips clothing with the antenna of the in-vivo apparatus in Embodiment 1 of this invention Usage state diagram of in-vivo device in embodiment 2 of the present invention Antenna configuration diagram of in-vivo device in Embodiment 2 of the present invention The figure which shows the means to equip clothing with the antenna of the in-vivo apparatus in Embodiment 2 of this invention Schematic diagram of antenna configuration of conventional in-vivo medical device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Human body 2 Heart 3 In-vivo antenna element 4 In-vivo apparatus 100 In-vivo apparatus 101 Monopole element 103 Housing | casing 104 Parasitic element 105 Adhesive sheet 106 Resin housing | casing 107 Matching circuit 109 Detection circuit 110 Substrate ground 112 Grounding point 201 1st Antenna element 202 Second antenna element 204 Protrusion 205 Clothing 206 Clothing back surface 207 Clothing surface 208 Hole

Claims (5)

An antenna element mounted on an in-vivo device disposed inside the living body;
A parasitic element disposed outside the living body in proximity to the antenna element,
An in-vivo device in which the in-vivo device communicates with an in-vitro device arranged outside the living body. A first antenna element mounted on the in-vivo device and slightly projecting from the in-vivo surface to the in-vivo surface;
A second antenna element disposed on the surface of the living body,
The in-vivo wireless device according to claim 1, wherein a protrusion on the living body surface of the first antenna element is connected to the second antenna element. The parasitic element and the second antenna element are composed of an adhesive sheet made of a conductive material having flexibility,
The in-vivo device according to claim 1 or 2, wherein the parasitic element and the second antenna element are arranged at a predetermined position on the surface of the living body. The in-vivo device according to claim 1 or 2, wherein the parasitic element and the second antenna element are provided at predetermined positions of clothing. The in-vivo device according to claim 4, wherein the parasitic element and the second antenna element are configured to be embedded in the clothing.

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