This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2011-072310 filed on Mar. 29, 2011, of which the contents are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a sensor, which can be embedded in a living body, for detecting an analyte.
2. Description of the Related Art
Heretofore, it has been customary in medical tests to dwell or embed a sensor in the living body of a test subject (user) for detecting an analyte in the blood or body fluid of the test subject, e.g., a blood glucose level in the blood. As disclosed in Japanese Patent No. 4065575, for example, the sensor is loaded in an insertion device that has an insertion needle for puncturing a human skin. The insertion needle with the sensor loaded therein is inserted into the test subject, and the sensor is dwelled or embedded in a desired position in the living body of the test subject. Thereafter, only the insertion needle is removed from the living body, leaving the sensor dwelling in the desired position.
However, when the insertion needle is removed from the living body after dwelling the sensor in the living body by the insertion needle, the sensor may possibly also be removed together with the insertion needle. If the sensor is also removed from the living body, the sensor may need to be inserted again into the living body or a new sensor may have to be used for insertion into the living body. The process of re-inserting the removed sensor into the living body or inserting a new sensor into the living body is tedious and time-consuming, and tends to place a burden on the test subject.
It is a general object of the present invention to provide a sensor which is prevented from being removed from a living body when an insertion needle is removed after placing the sensor in the living body, and which is capable of reliably dwelling in the living body after being inserted into the living body.
According to the present invention, there is provided a sensor adapted to be loaded in an insertion needle and inserted with the insertion needle into a living body for detecting an analyte, comprising a sensor body, a detector disposed in the sensor body, for detecting the analyte, and a retaining mechanism mounted on the sensor body, for retaining the sensor body in the living body against movement along a direction which is opposite to a direction along which the sensor body is inserted into the living body, wherein the retaining mechanism is made of a material whose hardness is lowered with time in the living body or a biodegradable material.
As described above, the sensor which is adapted to be loaded in the insertion needle and inserted with the insertion needle into the living body for detecting an analyte, includes the retaining mechanism on the sensor body which houses the detector therein, for retaining the sensor body in the living body against movement along the direction which is opposite to the direction along which the sensor body is inserted into the living body with the insertion needle. Specifically, after the sensor which is loaded in an insertion needle is inserted into the living body, the insertion needle is removed from the living body. At this time, the retaining mechanism securely retains the sensor body in the living body against removal together with the insertion needle from the living body.
The period of time in which the biodegradable material is decomposed in the living body can be adjusted based on the composition of the biodegradable material and the process by which it is manufactured. Therefore, the retaining mechanism can be hard enough to keep the sensor body in situ within the living body against removal when the sensor is inserted in the living body, and can be decomposed or softened for allowing the sensor body to be removed easily from the living body in the event that the sensor needs to be removed after use or that the sensor suffers malfunctioning or some trouble during use.
Since only the insertion needle is removed from the living body after placing the sensor in the living body, the sensor is not removed together with the insertion needle from the living body and it is not necessary to reinsert the sensor. As the sensor does not need to be reinserted into the living body, there is no undue burden imposed on the living body. The sensor thus kept dwelling within the living body can efficiently and reliably detect a desired analyte in the living body.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which preferred embodiments of the present invention are shown by way of illustrative example.
As shown in
As shown in
The sensor body 12 has a substantially rectangular cross-sectional shape including a storage area 18 formed therein which extends axially all the way through the sensor body 12 along the directions indicated by the arrows A, B. The storage area 18 houses therein the detector 14 which detects analytes such as components including glucose, uric acid, cholesterol, protein, minerals, etc. contained in the body fluid (e.g., the blood), and also pH, microorganisms, enzymes, etc., for example. The detector 14 is securely held in the storage area 18 by a sealant 20 made of a resin material. The sealant 20 encloses electric leads, not shown, therein.
The electric unit 15 is electrically connected to the detector 14 by the electric means (leads or the like). The electric unit 15 receives signals from the detector 14, processes the received signals, and sends the processed signals to a signal receiver, not shown.
The retaining mechanism 16 comprises at least one projection, e.g., two projections 22a, 22b, mounted on a side surface of the sensor body 12 which lies along the axial direction of the sensor body 12, i.e., in the directions indicated by the arrows A, B. The projections 22a, 22b project laterally from the side surface of the sensor body 12. Each of the projections 22a, 22b is of a V shape progressively wider and higher from the distal end toward the proximal end of the sensor body 12, i.e., along the direction indicated by the arrow B.
Stated otherwise, each of the projections 22a, 22b is of a V shape progressively higher and wider toward the proximal end of the embeddable sensor 10, i.e., along the direction indicated by the arrow B which is opposite to the direction along which the embeddable sensor 10 is inserted into the living body S, i.e., the direction indicated by the arrow A. The projections 22a, 22b are spaced from each other along the axial directions of the sensor body 12, i.e., along the directions indicated by the arrows A, B.
Each of the projections 22a, 22b has an end face on its proximal end which faces in the direction indicated by the arrow B, functioning as an engaging surface 24 for retaining the sensor body 12 in the living body S (see
As shown in
The projections 22a, 22b are made of a highly biocompatible material (or biocompatible polymeric material) such as polyacrylamide or the like. When the highly biocompatible material is dry right after the embeddable sensor 10 is inserted in the living body S, it is hard enough to retain the embeddable sensor 10 within the living body S. When the highly biocompatible material absorbs water in the living body S, it becomes gradually softer. Upon elapse of a certain period of time, e.g., several minutes, after the embeddable sensor 10 has been inserted in the living body S, the projections 22a, 22b becomes soft enough to allow the embeddable sensor 10 to be removed from the living body S. If the projections 22a, 22b are made of a material that is safe for the living body S (or a biodegradable material), e.g., sucrose, caramel, or the like, then they are gradually dissolved when they absorb water within the living body S, and are completely dissolved away upon elapse of a certain period of time after the embeddable sensor 10 has been inserted in the living body S.
The projections 22a, 22b may be made of a material whose hardness varies depending on a change in the ambient temperature, including gelatin or the like. If the projections 22a, 22b are made of such a material, then when the embeddable sensor 10 is outside of the living body S, the projections 22a, 22b keep a certain level of hardness, and when the embeddable sensor 10 is inserted into the living body S, the projections 22a, 22b are heated by the temperature of the living body S, gradually reducing their hardness.
An insertion needle 28 of a sensor inserting device 26 for inserting the embeddable sensor 10 into the living body S will briefly be described below with reference to
The insertion needle 28 has a generally rectangular or circular cross-sectional shape or the like. Specifically, the insertion needle 28 includes an open groove 30 formed in and extending along a side wall thereof. As a result, the insertion needle 28 is cross-sectionally U-shaped, C-shaped, V-shaped or the like. The insertion needle 28 has a proximal end integral with a grip 32 which is gripped to insert the embeddable sensor 10 into the living body S. The embeddable sensor 10 is inserted into the insertion needle 28 from its distal end with the projections 22a, 22b moving in and along the open groove 30. When the embeddable sensor 10 is inserted in the insertion needle 28, the projections 22a, 22b project out of the open groove 30, as shown in
The embeddable sensor 10 according to the first embodiment of the present invention is basically constituted as described above. A process of inserting the embeddable sensor 10 into the living body S will be described below with reference to
First, the embeddable sensor 10 is inserted into the insertion needle 28 of the sensor inserting device 26 from its distal end. Then, the insertion needle 28 is positioned so as to face a region of the test subject into which the embeddable sensor 10 is to be inserted. As shown in
After having confirmed that the embeddable sensor 10 is placed in the desired position in the living body S, the insertion needle 28 is pulled out of the living body S. At this time, the projections 22a, 22b are held in engagement with the nearby tissue of the living body S against removal along the direction indicated by the arrow B along which the insertion needle 28 is pulled out. Therefore, the embeddable needle 10 is prevented from being removed together with the insertion needle 28 out of the living body S, but remains dwelling in the desired position, as shown in
More specifically, when the embeddable sensor 10 is pulled along the direction out of the living body S, i.e., along the direction indicated by the arrow B, since the engaging surfaces 24 of the projections 22a, 22b lie substantially perpendicularly to the direction indicated by the arrow B, the projections 22a, 22b effectively engage the nearby tissue of the living body S, firmly retaining the embeddable sensor 10 against removal from the living body S.
When the insertion needle 28 is removed out of the living body S, the projections 22a, 22b of the embeddable sensor 10 are located in the open groove 30 and do not contact and hence interfere with the insertion needle 28.
While the embeddable sensor 10 is dwelling in the living body S, the detector 14 detects a desired analyte concentration, e.g., a glucose concentration, in the blood, and outputs a detection signal representative of the detected analyte concentration to the electric unit 15.
As shown in
Even when the projections 22a, 22b are softened, the embeddable sensor 10 does not freely move in the living body S, but is retained in situ within the tissue of the living body S.
According to the first embodiment, as described above, the embeddable sensor 10 which is embedded in the living body S to detect a blood glucose level, for example, thereof includes at least one of the projections 22a, 22b on one side surface of the sensor body 12 which houses the detector 14 therein. Each of the projections 22a, 22b is progressively higher and wider from the distal end toward the proximal end of the sensor body 12, i.e., along the direction indicated by the arrow B. Therefore, when only the insertion needle 28 is removed after the embeddable sensor 10 has been inserted together with the insertion needle 28 into the living body S, the projections 22a, 22b engage the nearby tissue of the living body S, preventing the embeddable sensor 10 from being dragged together with the insertion needle 28 out of the living body S.
The embeddable sensor 10 thus remains dwelling in the desired position in the living body S, for detecting the concentration of a desired analyte in the living body S.
The projections 22a, 22b of the embeddable sensor 10 are made of a material that is safe for the living body S, e.g., sucrose, caramel, or the like, or a highly biocompatible material such as polyacrylamide or the like. Therefore, upon elapse of a certain period of time after the embeddable sensor 10 has been placed in the living body S, the projections 22a, 22b are gradually softened with time by absorbing water in the living body S, lowering their hardness. Therefore, the projections 22a, 22b lose their capability to retain the embeddable sensor 10 within the living body S. If the embeddable sensor 10 suffers a malfunction or other trouble, therefore, the embeddable sensor 10 can easily and reliably be removed from the living body S after the hardness of the projections 22a, 22b is lowered upon elapsed of a certain period of time.
The projections 22a, 22b are progressively narrower and lower along the direction in which the embeddable sensor 10 is inserted into the living body S, i.e., along the direction indicated by the arrow A. Therefore, when the embeddable sensor 10 is inserted into the living body S, it undergoes relatively small resistance from the living body S and imposes only a small burden on the test subject.
The projections 22a, 22b have the respective engaging surfaces 24 as their end faces on the proximal ends thereof along the direction indicated by the arrow B which is opposite to the direction along which the embeddable sensor 10 is inserted into the living body S, i.e., the direction indicated by the arrow A. The engaging surfaces 24 of the projections 22a, 22b lie substantially perpendicularly to the direction in which the embeddable sensor 10 is inserted into the living body S, i.e., the axial directions of the sensor body 12, i.e., the directions indicated by the arrows A, B. Therefore, when the embeddable sensor 10 is pulled along the direction indicated by the arrow B, the engaging surfaces 24 engage the nearby tissue of the living body S, keeping the embeddable sensor 10 securely dwelling in the living body S.
As shown in
A sensor inserting device 62 for inserting the embeddable sensor 50 into the living body S includes an insertion needle 64. The insertion needle 64 has a generally semicircular cross-sectional shape. The ring 54 of the sensor body 56 can be inserted and held in the insertion needle 64. When the embeddable sensor 50 is inserted and held in the distal end portion of the insertion needle 64, the base 52 of the sensor body 56 protrudes out of the insertion needle 64.
After the embeddable sensor 50 is placed together with the insertion needle 64 in the desired position in the living body S, the insertion needle 64 is pulled out of the living body S along the direction indicated by the arrow B. At this time, at least one of the projections 22a, 22b is held in engagement with the nearby tissue of the living body S against removal along the direction indicated by the arrow B. As a consequence, the embeddable sensor 50 is prevented from being removed together with the insertion needle 64 out of the living body S, but remains dwelling in the desired position. The projections 22a, 22b of the embeddable sensor 50 which is dwelling in the living body S are gradually softened with time by absorbing water or the like in the living body S, lowering their hardness. Therefore, the projections 22a, 22b lose their capability to retain the embeddable sensor 50 within the living body S. The embeddable sensor 50 can thus easily be removed from the living body S.
As shown in
As with the embeddable sensors 10, 50 according to the first and second embodiments, each of the projections 22a, 22b is of a V shape progressively wider and higher from the distal end toward the proximal end of the sensor body 102, i.e., along the direction indicated by the arrow B.
A sensor inserting device 106 for inserting the embeddable sensor 100 into the living body S includes an insertion needle 108. The insertion needle 108 has a generally U-shape cross section. The insertion needle 108 has an opening 110 formed in and extending along a side wall thereof. The sensor body 102 can be inserted and held in the insertion needle 108 with the projections 22a, 22b disposed in the opening 110 and projecting out of the opening 110.
After the embeddable sensor 100 are placed together with the insertion needle 108 in the desired position in the living body S, the insertion needle 108 is pulled out of the living body S along the direction indicated by the arrow B. At this time, at least one of the projections 22a, 22b is held in engagement with the nearby tissue of the living body S against removal along the direction indicated by the arrow B. As a consequence, the embeddable sensor 100 is prevented from being removed together with the insertion needle 108 out of the living body S, but remains dwelling in the desired position.
When the insertion needle 108 is removed out of the living body S, the projections 22a, 22b of the embeddable sensor 10 are located in the opening 110 and do not contact and hence interfere with the insertion needle 108. The projections 22a, 22b of the embeddable sensor 100 which is dwelling in the living body S are gradually softened with time by absorbing water in the living body S, lowering their hardness. Therefore, the projections 22a, 22b lose their capability to retain the embeddable sensor 100 within the living body S. The embeddable sensor 100 can thus easily be removed from the living body S.
In the embeddable sensors 10, 50, 100 according to the first, second, and third embodiments, the projections 22a, 22b are illustrated as being of a V shape which is progressively higher and wider toward the proximal end of the embeddable sensors 10, 50, 100, i.e., along the direction indicated by the arrow B which is opposite to the direction along which the embeddable sensors 10, 50, 100 are inserted into the living body S, i.e., the direction indicated by the arrow A. However, the projections 22a, 22b are not limited to any particular shapes insofar as they are progressively higher or wider along the direction opposite to the direction in which the embeddable sensors 10, 50, 100 are inserted into the living body S.
The embeddable sensors 10, 50, 100 according to the first, second, and third embodiments are illustrated as having two projections 22a, 22b. However, the embeddable sensor according to the present invention may have only one projection or three or more projections.
The principles of the present invention are not limited to an embeddable sensor that will be fully inserted in the living body S, but may be applicable to an embeddable sensor which has at least a detector 14, 60, 104 insertable in the living body S with other parts exposed outside of the living body.
Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.
Number | Date | Country | Kind |
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2011-072310 | Mar 2011 | JP | national |