Patent Publication Number: US-2009234203-A1

Title: Capsule for medical use

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The disclosures herein relate to a capsule for use with a medical device for performing medical tests, treatments, and procedures wherein the capsule is designed to pass through a lumen of a human or animal body. 
     2. Description of the Related Art 
     A capsule designed to pass through a tract of a human or animal body has been studied for use with a medical device for performing medical tests, treatments, and procedures. Such a capsule has an electronic device (e.g., a camera and a communication unit) embedded therein for use in medical tests. The capsule is swallowed and passed through the gastrointestinal tract by the peristaltic movements of the stomach and intestines for discharge to outside the body. 
     Pictures of the digestive tract are taken and the image data are transmitted while the capsule is inside the body. In consideration of this, the design and structure of the capsule have been improved over and over again by taking into account hermetic sealing, easiness to swallow, easiness to be propelled, and the like (see Japanese Patent Application Publication No. 2003-135387, for example). 
     A related-art capsule for use with a medical device has an antenna embedded therein for performing radio communication with an external device situated outside the body. Such a capsule structure may undermine the quality of communication. 
     Accordingly, there is a need for a capsule that can maintain satisfactory communication conditions for use with a medical device. 
     SUMMARY OF THE INVENTION 
     It is a general object of the present invention to provide a capsule for medical use that substantially eliminates one or more problems caused by the limitations and disadvantages of the related art. 
     According to one embodiment, a capsule for medical use which is to be passed through a tract of a human or animal body includes a capsule-shape case, a wire antenna placed in a wrapped or folded state on at least a portion of an outer surface of the case, and a fixing member configured to fix the wire antenna in the wrapped or folded state, wherein the fixing member is configured to release the antenna inside the tract. 
     A capsule for medical use which is to be passed through a tract of a human or animal body includes a capsule-shape case, an antenna part made of a metal foil disposed on a surface of the case, and a ground part made of a metal foil disposed on the surface of the case. 
     According to at least one embodiment, a capsule that can maintain satisfactory communication conditions for use with a medical device is provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a capsule for use with a medical device according to a first embodiment; 
         FIG. 2  is a cross-sectional view of the medical device capsule of the first embodiment; 
         FIGS. 3A through 3C  are drawings illustrating the way an antenna part of the medical device capsule of the first embodiment extends itself inside a body; 
         FIGS. 4A and 4B  are drawings illustrating a medical device capsule according to a second embodiment; 
         FIGS. 5A and 5B  are drawings illustrating a medical device capsule according to a third embodiment; 
         FIGS. 6A and 6B  are drawings illustrating a medical device capsule according to a fourth embodiment; 
         FIGS. 7A and 7B  are drawings illustrating a medical device capsule according to a fifth embodiment; 
         FIGS. 8A through 8C  are drawings illustrating a medical device capsule according to a sixth embodiment; and 
         FIGS. 9A through 9C  are drawings illustrating a medical device capsule according to a seventh embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, a description will be given of embodiments of a capsule for use with a medical device. 
     First Embodiment 
       FIG. 1  is a perspective view of a capsule for use with a medical device according to a first embodiment. 
     A capsule  10  is a resin cylinder having ends thereof rounded into a hemispherical shape. The capsule  10  is 10 mm in length and 6 mm in diameter. The resin material constituting the capsule  10  may be an ABS (acrylonitrile butadiene styrene) resin, for example. 
     The capsule  10  is assembled by hermitically connecting a pair of capsule parts  11  and  12 . An end  11   a  of the capsule part  11  has an antenna part  13  wrapped around its outer circumferential surface. 
       FIG. 2  is a cross-sectional view of the medical device capsule of the first embodiment. 
     The capsule part  11  has a retracted surface  11 A on which the antenna part  13  is wrapped around. 
     The antenna part  13  has one end thereof inserted into a hole  11   b  provided in the capsule part  11  for connection with a transmitter  14  provided inside the capsule  10 . The remainder of the antenna part  13  is wrapped such that the other end of the antenna part  13  reaches the ultimate point of the end  11   a  of the capsule part  11 . The antenna part  13  may be made of copper. 
     The antenna part  13  is fixed by gelled gelatin  15  in such a shape that the antenna part  13  is wrapped around the outer circumferential surface of the capsule part  11 . Namely, the antenna part  13  is fixed by the gelatin  15  serving as a fixing member while it is wrapped around the outer circumferential surface of the capsule part  11 . 
     The length of the antenna part  13  matches the radio frequency that is employed for radio communication. For example, the length of the antenna part  13  is approximately 190 mm when the radio communication frequency is 400 MHz. Further, the length is approximately 94 mm for a radio frequency of 80 MHz, approximately 31 mm for a radio frequency of 2.4 GHz, and approximately 13 mm for a radio frequency of 5.8 GHz. 
     The thickness of the antenna part  13  may preferably be 0.05 mm, for example. If a UWB (Ultra Wide Band) frequency is used, the thickness may be increased to 0.1 mm to match such wide-band communication. 
     The antenna part  13  is configured to receive an electrical power from the transmitter  14  situated inside the capsule  10 . Data is transmitted through the collaboration of the antenna part  13  with a ground part  16  disposed inside the end  11   a  of the capsule part  11 . 
     The transmitter  14  is coupled to an imaging device (not illustrated) disposed inside the capsule  10 , and is configured to transmit image data supplied from the imaging device to an external device situated outside the body. 
     It suffices for the gelatin  15  to be edible as a human swallows the capsule  10 . The gelatin  15  is preferably configured to maintain the antenna part  13  in the wrapped state prior to being swallowed and to release the antenna part  13  from the wrapped state after being swallowed. In consideration of this, the composition and amount of the gelatin  15  are adjusted such that the gelatin  15  is dissolved while passing through the esophagus. 
       FIGS. 3A through 3C  are drawings illustrating the way the antenna part  13  of the medical device capsule  10  of the first embodiment extends itself inside a body, A temporal sequence progresses in the following order:  FIG. 3A ,  FIG. 3B , and  FIG. 3C . 
     As  FIGS. 3A through 3C  are provided for the purpose of explaining the way the gelatin  15  is dissolved, the interior structure of the capsule  10  is omitted from the illustration. 
       FIG. 3A  illustrates the state of the capsule  10  prior to being swallowed by a human or animal. In this state, the antenna part  13  is kept in the wrapped state by the gelled gelatin  15 . 
       FIG. 3B  illustrates the state of the capsule  10  immediately after being swallowed by a human or animal. In this state, gelatin  15  is almost all dissolved and gone, but the antenna part  13  is not yet released from the wrapped state. 
       FIG. 3C  illustrates the state in which the gelatin  15  is all dissolved and gone, and the antenna part  13  is extended inside the intestine of the human or animal body. The capsule  10  is propelled to the right in the figure through the peristaltic movements of the intestine, so that the antenna part  13  is extended to trail behind the capsule  10  in its travel direction. 
     The occurrence of such extension of the antenna part  13  is not limited to inside the intestine, but may similarly occur inside the stomach or any other digestive tract. 
     When the capsule  10  is expelled to outside the body, the antenna part  13  is also expelled. The load on the human or animal body using the capsule  10  is about the same as the load imposed by a conventional medical device capsule. 
     As described above, the medical device capsule  10  of the first embodiment has the antenna part  13  extending inside the digestive tract of a human or animal body, so that its communication is not likely to be affected by an imaging device and the like disposed inside the capsule  10 , thereby achieving satisfactory communication conditions. 
     The measurements of the capsule  10  and the antenna part  13  are not limited to the above-described values. The capsule  10  may have a length of 5 to 20 mm and a diameter of 5 to 10 mm. 
     Likewise, the antenna part  13  may have a length of 13 to 190 mm and a thickness of 0.05 to 0.1 mm. 
     The above description has been given with reference to an example in which the antenna part  13  is made of copper. This is not a limiting example, and the antenna part  13  may be made of an alloy including copper (Cu), nickel-chrome (Ni—Cr), and an amorphous alloy inclusive of ferrite. As an alloy inclusive of amorphous ferrite, an amorphous Fe—Si—B alloy (Fe: iron, Si: silicon, B: boron) may be used. 
     The amorphous Fe—Si—B alloy has a shape memory property. The antenna part  13  may be given a memorized shape such that the antenna part  13  returns to an extended state at 30 degrees Celsius close to the normal human body temperature. 
     Nickel-chrome has a high thermal conductivity. In consideration of this, a small amount of electric current may be applied to the antenna part  13  when the capsule  10  is expected to be at a proper position inside the body. This results in the amorphous Fe—Si—B alloy being reliably extended inside the body. 
     Although the above description has been provided with reference to an example in which the gelatin  15  is used as a fixing member, the fixing member is not limited to the gelatin  15 . The fixing member may be of any mechanism as long as it can keep the antenna part  13  in the wrapped state prior to swallowing the capsule  10  and can release the antenna part  13  from the wrapped state by dissolving, breaking apart, or falling off inside the digestive tract after the capsule  30  is swallowed. 
     Second Embodiment 
       FIGS. 4A and 4B  are drawings illustrating a medical device capsule according to a second embodiment.  FIG. 4A  is a perspective view, and  FIG. 4B  is a view illustrating a state in which the antenna is extended. A capsule  20  for use with a medical device according to the second embodiment differs from that of the first embodiment in that an anchor is provided at the tip of the antenna part  13 . The remaining parts are the same as those of the first embodiment. The same elements are referred to by the same numerals, and a description thereof will be omitted. 
     The capsule  20  of the second embodiment has an anchor  13 A at the tip of the antenna part  13 . The anchor  13 A serves to further extend the antenna part  13  to improve the communication conditions inside the human or animal body. 
     The anchor  13 A may be a foldable weight made of resin, which is 3 mm long, 6 mm wide, and 6 mm high in a folded state. As the anchor  13 A detaches from the capsule  20 , the antenna part  13  extends. 
     As shown in  FIG. 4A , the anchor  13 A forms an additional projection at the end of the capsule  20  prior to being swallowed, compared to the capsule  10  of the first embodiment. The capsule  20  may still be 10 mm long and 6 mm wide, so that the easiness to swallow is about the same between the capsule  10  and the capsule  20 . 
     As illustrated in  FIG. 4B , the anchor  13 A unfolds inside the intestine to function as resistance against the traveling movement of the capsule  20 , thereby helping to extend the antenna part  13 . 
     Accordingly, the medical device capsule  20  of the second embodiment has the anchor  13 A assisting the antenna part  13  in extending inside the digestive tract of a human or animal body, so that its communication is not likely to be affected by an imaging device and the like disposed inside the capsule  10 , thereby achieving satisfactory communication conditions. 
     The mounting location of the anchor  13 A is not limited to the tip of the antenna part  13 . The anchor  13 A may be attached to any position along the extension of the antenna part  13 . 
     The material of the anchor  13 A is not limited to resin, and may be made of gelatin that is dissolvable inside the body. In such a case, the composition and amount of the gelatin are selected such that the anchor  13 A remains to exist and continues to function until the very last minute, immediately prior to expulsion from the body, unlike those of the gelatin  15  that serves to fix the antenna part  13  prior to being swallowed. 
     Third Embodiment  
       FIGS. 5A and 5B  are drawings illustrating a medical device capsule according to a third embodiment.  FIG. 5A  is a perspective view of an antenna  33  attached to a capsule  30 , and  FIG. 5B  is a view illustrating the antenna  33  before being attached to the capsule  30 . 
     As shown in  FIG. 5A , the capsule  30  is assembled by hermetically connecting a pair of capsule parts  31  and  32 . The shape of the capsule part  32  is the same as the shape of the capsule part  12  of the first embodiment. Unlike the capsule part  11  of the first embodiment, however, the capsule part  31  does not have the retracted surface  11 A formed thereon. The capsule  30  is 20 mm in length and 6 mm in diameter. 
     The antenna part  33  and ground part  36  are pasted onto the capsule parts  32  and  31 , respectively, and are covered with resin coating. The resin that coats the antenna part  33  and the ground part  36  may be polyimide, for example. 
     As shown in  FIG. 5B , the antenna part  33  is a copper foil having a home-plate shape in its plan view, and the ground part  36  is a copper foil having a rectangular shape in its plan view. 
     With respect to the antenna part  33 , length A is 18 mm, and width B is 8 mm, with an angle θ relative to a centerline being 63 degrees. An electrical power is supplied to the antenna part  33  at a supply point  33 A situated at the apex of the home-plate shape. 
     The ground part  36  may have a length C of 18 mm (equal to the length of the antenna part  33 ) and a width D of 8 mm. 
     The shape of the antenna part  33  and ground part  36  is designed such that UWE communication is attainable. This antenna has an excellent communication capacity that achieves a VSWR (voltage standing wave ratio) of 2.0 or less for a range of 3.1 GHz to 10.6 GHz. 
     Such an antenna part  33  and ground part  36  are pasted to the surfaces of the capsule parts  32  and  31 , respectively, as illustrated in  FIG. 5A . As in the case of the capsule of the first embodiment, a transmitter is provided to transmit image data at high speed to an external apparatus situated outside the body as an imaging device inside the capsule takes pictures. 
     The antenna part  33  is coupled to the embedded transmitter through a hole as in the case of the capsule  10  of the first embodiment, and this transmitter supplies electrical power to the supply point  33 A. 
     In the third embodiment, the transmitter corresponding to the transmitter  14  of the first embodiment is configured to perform UWB (Ultra Wide Band) communication. 
     As described above, the medical device capsule  30  of the third embodiment can perform UWB communication between inside the digestive tract of a human or animal body and an external apparatus situated outside the body. 
     Because UWB communication is employed, the position of the capsule  30  inside the digestive tract can be identified by measuring the distances from a plurality of external apparatuses situated outside the body. 
     Further, not only the antenna part  33  but also the ground part  36  is disposed on the outer surface of the capsule  30 . Such a configuration reduces the influence of noise generated by the imaging device or the like provided inside the capsule  30 , thereby achieving satisfactory communication conditions. 
     The measurements of the capsule  30 , the antenna part  33 , and the ground part  36  are not limited to the above-described values. The capsule  30  may have a length of 5 to 20 mm and a diameter of 5 to 10 mm. 
     With respect to the antenna part  33 , the length A may be 15 to 30 mm, and the width B may be 2 to 8 mm, with the angle θ relative to the center line being 45 to 70 degrees. For the ground part  36 , the length C may be 15 to 30 mm, and the width D may be 2 to 8 mm. 
     Fourth Embodiment 
       FIGS. 6A and 6B  are drawings illustrating a medical device capsule according to a fourth embodiment.  FIG. 6A  is a perspective view of an antenna  43  attached to a capsule  40 , and  FIG. 6B  is a view illustrating the antenna  43  before being attached to the capsule  40 . 
     As shown in  FIG. 6A , the capsule  40  is assembled by hermetically connecting a pair of capsule parts  41  and  42 . The capsule parts  41  and  42  of the fourth embodiment are divided in a different direction than the capsule parts of the first through third embodiments. Namely, a dividing line extends in the longitudinal direction of the capsule  40 . No retracted surface is provided. The capsule  40  is 10 mm in length and 6 mm in diameter. 
     The antenna part  43  and ground part  46  are pasted onto the capsule parts  41  and  42  of the capsule  40 , respectively, and are covered with resin coating. This configuration is similar to that of the third embodiment. The resin that coats the antenna part  43  and the ground part  46  may be polyimide, for example. 
     As shown in  FIG. 6B , the antenna  43  is a copper foil having a T-letter shape in its plan view, and the ground part  46  is a copper foil having a rectangular shape in its plan view. 
     With respect to the antenna part  43 , length E is 8 mm, and width F is 3 mm, with width G being 1 mm. An electrical power is supplied to the antenna part  43  at a supply point  43 A situated at the tip of the T-letter shape. 
     The ground part  46  may have a length H of 8 mm (equal to the length of the antenna part  43 ) and a width 1 of 10 mm. 
     The shape of the antenna part  43  and ground part  46  is designed such that UWB (Ultra Wide Band) communication is attainable. This antenna has an excellent communication capacity that achieves a VSWR (voltage standing wave ratio) of 2.0 or less for a range of 3 GHz to 10 GHz or 6 GHz to 20 GHz. 
     Such an antenna  43  and ground part  46  are pasted to the surfaces of the capsule parts  42  and  41 , respectively, as illustrated in  FIG. 6A . As in the case of the capsule of the first embodiment, a transmitter is provided to transmit image data at high speed to an external apparatus situated outside the body as an imaging device inside the capsule takes pictures. 
     The antenna  43  is coupled to the embedded transmitter through a hole as in the case of the capsule  10  of the first embodiment, and this transmitter supplies an electrical power to the supply point  43 A. 
     In the fourth embodiment, the transmitter corresponding to the transmitter  14  of the first embodiment is configured to perform UWB (Ultra Wide Band) communication. 
     As described above, the medical device capsule  40  of the fourth embodiment can perform UWB communication between inside the digestive tract of a human or animal body and an external apparatus situated outside the body. 
     Further, not only the antenna  43  but also the ground part  46  is disposed on the outer surface of the capsule  40 . Such a configuration reduces the influence of noise generated by the imaging device or the like provided inside the capsule  40 , thereby achieving satisfactory communication conditions. 
     The measurements of the capsule  40 , the antenna part  43 , and the ground part  46  are not limited to the above-described values. The capsule  40  may have a length of 5 to 20 mm and a diameter of 5 to 10 mm. 
     With respect to the antenna part  43 , the length E may be 4 to 8 mm, and the width F may be 1 to 4 mm, with the width G being 0.5 mm. For the ground part  46 , the length H may be 4 to 8 mm, and the width I may be 4 to 10 mm. 
     Fifth Embodiment 
       FIGS. 7A and 7B  are drawings illustrating a medical device capsule according to a fifth embodiment.  FIG. 7A  is a perspective view of an antenna  53  attached to a capsule  50 , and  FIG. 7B  is a view illustrating the antenna  53  in its extended state. 
     The medical device capsule  50  of the fifth embodiment includes capsule parts  55  and  52 . An anchor  53 A is provided at the tip of the antenna part  53 , and a tip portion  53 B of the antenna part  53  is adhered to the anchor  53 A. In this manner, the capsule  50  for medical use differs from that of the second embodiment in that the tip portion  53 B of the antenna part  53  is not extended but adhered to the anchor  53 A provided at the tip of the antenna part  53 . Namely, a portion of the wire of the antenna part  53  is kept adhered to the anchor  53 A in its wrapped state. 
     As the tip portion  53 B of the antenna part  53  is adhered to the anchor  53 A, it is easier to extend the antenna part  53  as shown in  FIG. 7B . 
     Further, the antenna tip portion  53 B is kept in its wrapped state without being unfolded, thereby reducing a total length of the antenna extension. For example, the length of the antenna part  53  is approximately 190 mm when the radio communication frequency is 400 MHz. With the provision of the adhered tip portion  53  in the medical use capsule  50  of the fifth embodiment, the total length of the antenna extension may be reduced to 60 mm or 90 mm, which is approximately ⅓ or ½ of the original length. 
     Sixth Embodiment 
       FIGS. 8A through 8C  are drawings illustrating a medical device capsule according to a sixth embodiment.  FIG. 8A  is a partial cross-sectional view of a capsule as viewed from a lateral direction.  FIG. 8B  is a cross-sectional view of the capsule as viewed from its back.  FIG. 8C  is a view illustrating a state in which an antenna is extended. A capsule  60  for use with a medical device according to the sixth embodiment differs from that of the first embodiment in the structure of an antenna part  63 . 
     As illustrated in  FIGS. 8A and 8B , the antenna part  63  of the medical device capsule  60  of the sixth embodiment has nine helical parts  63 A, each of which is a coil of the antenna wire. The antenna part  63  is a single conductive wire including the nine helical parts  63 A. 
     The antenna part  63  is accommodated in a storage area  60 A located at a tailing end of the capsule  60  such that the helical parts  63 A and the remaining straight-line part are folded together. The antenna part  63  stored in the storage area  60 A is fixed by gelled gelatin  65  as in the case of the medical device capsule  10  of the first embodiment. 
     When the medical device capsule  60  enters the body, the gelatin is dissolved, so that the antenna part  63  extends as shown in  FIG. 8C . The helical parts  63 A retain their coil shape. 
     In this manner, the total length of the antenna part  63  in its extended state is reduced due to the coils of the helical parts  63 A, which suppress the extension of the antenna part  63 . The capsule  60  for use with a medical device according to the sixth embodiment is advantageous especially when the length of the antenna part  63  is preferably shorter than otherwise. 
     Moreover, the helical parts  63 A create electromagnetic induction. The magnetic field generated by this electromagnetic induction may be detected by an antenna or radar situated outside the body to detect the position of the capsule  60  inside the digestive tract. 
     Seventh Embodiment 
       FIGS. 9A through 9C  are drawings illustrating a medical device capsule according to a seventh embodiment.  FIG. 9A  is a perspective view, and  FIG. 9B  is a back view.  FIG. 9C  is a view illustrating a state in which the antenna is extended. A capsule  70  for use with a medical device according to the sixth embodiment differs from that of the first embodiment in the structure of an antenna part  73 . 
     As illustrated in  FIGS. 9A and 9B , the antenna part  73  of the medical device capsule  70  of the seventh embodiment has three antenna portions  73 A,  73 B, and  73 C. The antenna portions  73 A,  73 B, and  73 C each have different bandwidth characteristics. 
     The antenna portion  73 A is a 2.4-GHz-band antenna, the antenna portion  73 B is an 800-MHz-band antenna, and the antenna portion  73 C is a 400-MHz-band antenna. The length of each of these antenna portions is designed to be approximately ¼ of the corresponding band wavelength. The antenna portion  73 A is 31.2 mm long because the wavelength of a 2.4-GHz radio wave is 125 mm. 
     Similarly, the antenna portion  73 B is 90 mm long because the wavelength of an 800-MHz radio wave is 370 mm. Further, the antenna portion  73 C is 190 mm long because the wavelength of a 400-MHz radio wave is 750 mm. 
     The three antenna portions  73 A,  73 B, and  73 C are accommodated in a storage area  70 A situated at a trailing end of the medical device capsule  70  such that they are coiled in a spiral shape in its plan view. The antenna portions  73 A,  73 B, and  73 C accommodated in the storage area  70 A are fixed by gelled gelatin  75 . 
     When the medical device capsule  70  enters the body, the gelatin is dissolved, so that the antenna portions  73 A,  73 B, and  73 C extend as shown in  FIG. 9C . 
     The medical device capsule  70  described above can utilize three different frequency bands, thereby being able to efficiently transmit data to outside the body. The capsule  70  for medical use according to the seventh embodiment is advantageous especially when the number of data types and/or the amount of data are large. 
     The descriptions of medical device capsules of exemplary embodiments have been provided heretofore. The present invention is not limited to these embodiments, but various variations and modifications may be made without departing from the scope of the present invention. 
     The present application is based on Japanese priority applications No. 2008-066549 filed on Mar. 14, 2008 and No. 2008-208534 filed on August  13 ,  2008 , with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.