阅读说明：本技术 双边驱动闭环人工胰腺 (Bilateral drive closed-loop artificial pancreas ) 是由 杨翠军 于 2020-08-26 设计创作，主要内容包括：本发明公开了一种双边驱动闭环人工胰腺,包括：检测模块；输注模块,输注模块包括：储药单元；分别与螺杆相连接的活塞和设置有轮齿的驱动轮；与驱动轮相配合运作的驱动单元,驱动单元绕转轴带动不同的驱动部在不同转动方向上分别推动位于不同驱动轮上的轮齿；与驱动单元相连接的动力单元,动力单元对驱动单元施加两个方向的作用力；程序模块控制输注模块输注当前所需剂量的胰岛素。该闭环人工胰腺具有较高的输注效率,增强用户体验。(The invention discloses a bilateral drive closed-loop artificial pancreas, which comprises: a detection module; an infusion module, the infusion module comprising: a medicine storage unit; a piston and a driving wheel with gear teeth, which are respectively connected with the screw; the driving unit is matched with the driving wheels to operate, drives different driving parts to respectively push the gear teeth on different driving wheels in different rotating directions around the rotating shaft; the power unit is connected with the driving unit and applies acting force in two directions to the driving unit; the program module controls the infusion module to infuse the currently desired dose of insulin. This artificial pancreas of closed loop has higher infusion efficiency, reinforcing user experience.)

1. A bilateral drive closed-loop artificial pancreas, comprising:

a detection module for continuously detecting a real-time blood glucose level parameter;

an infusion module, the infusion module comprising:

a medicine storage unit;

the driving wheel drives the screw rod to move through rotation so as to push the piston arranged in the medicine storage unit to advance;

the driving unit is matched with the driving wheel to operate and comprises at least two driving parts, and the driving unit drives different driving parts to respectively push the gear teeth on different driving wheels in different rotating directions around a rotating shaft so as to enable the driving wheel to rotate;

the power unit is connected with the driving unit and applies acting force in two directions to the driving unit to enable the driving unit to rotate around the rotating shaft in two directions; and

and the program module is connected with the detection module and the infusion module and controls the output of the power unit force so as to control the infusion module to infuse the insulin with the currently required dosage.

2. The bilateral drive closed loop artificial pancreas of claim 1, wherein the drive wheel includes at least two sub-wheels.

3. The bilateral drive closed-loop artificial pancreas as claimed in claim 2, wherein the drive wheel comprises two sub-wheels, the rotation shaft is disposed between the two sub-wheels, one or more of the drive portions are disposed on both sides of the drive unit, and each sub-wheel is engaged with at least one of the drive portions.

4. The bilateral drive closed-loop artificial pancreas as claimed in claim 3, wherein two of the driving portions are disposed on both sides of the driving unit, and the two driving portions on one side of the driving unit are disposed up and down or left and right.

5. The bilateral drive closed-loop artificial pancreas of claim 1, wherein the power unit comprises an electrically heated linear drive or an electrically driven linear drive.

6. The bilaterally-driven closed-loop artificial pancreas of claim 1, wherein the drive unit has a plurality of different rotational amplitudes or rotational rates and the infusion module has a plurality of different unit infusion amounts or infusion rates.

7. The single-sided driven closed-loop artificial pancreas as claimed in claim 1, wherein two of the detection module, the program module and the infusion module are connected to each other to form a unitary structure and are attached to a third module at different positions on the skin.

8. The single-sided drive closed loop artificial pancreas as claimed in claim 1, wherein the detection module, the program module and the infusion module are connected to form an integral structure and are adhered to the same position of the skin.

Technical Field

The invention mainly relates to the field of medical instruments, in particular to a bilateral drive closed-loop artificial pancreas.

Background

The pancreas in a normal human body can automatically monitor the glucose content in the blood of the human body and secrete the required insulin/glucagon automatically. The function of pancreas of diabetics is abnormal, and insulin required by human bodies cannot be normally secreted. Therefore, diabetes is a metabolic disease caused by abnormal pancreatic functions of a human body, and is a lifelong disease. At present, the medical technology can not cure the diabetes radically, and only can control the occurrence and the development of the diabetes and the complications thereof by stabilizing the blood sugar.

Diabetics need to test their blood glucose before injecting insulin into their body. At present, most detection means can continuously detect blood sugar and transmit blood sugar data to remote equipment in real time, so that a user can conveniently check the blood sugar data. The method needs the detection device to be attached to the surface of the skin, and the probe carried by the detection device is penetrated into subcutaneous tissue fluid to finish detection. According to the blood sugar value detected by the CGM, the infusion equipment inputs the currently required insulin subcutaneously so as to form a closed-loop or semi-closed-loop artificial pancreas. At present, a detection device and an infusion device are connected with each other, the detection device and the infusion device form a closed-loop artificial pancreas through processing of a program module, and the infusion device automatically administers medicine according to data of the detection device.

However, the driving mode of the existing artificial pancreas for infusing the medicine is single, the infusion efficiency is low, and the user experience is poor.

Therefore, a closed-loop artificial pancreas with diversified driving modes and high infusion efficiency is urgently needed in the prior art.

Disclosure of Invention

The embodiment of the invention discloses a bilateral drive closed-loop artificial pancreas which has diversified drive modes, higher infusion efficiency and enhanced user experience.

The invention discloses a bilateral drive closed-loop artificial pancreas, which comprises: the detection module is used for continuously detecting real-time blood sugar level parameters; an infusion module, the infusion module comprising: a medicine storage unit; the driving wheel drives the screw rod to move by rotating so as to push the piston arranged in the medicine storage unit to advance; the driving unit is matched with the driving wheels to operate and comprises at least two driving parts, and the driving unit drives different driving parts to respectively push the gear teeth on different driving wheels in different rotating directions around the rotating shaft so as to enable the driving wheels to rotate; the power unit is connected with the driving unit and applies acting force in two directions to the driving unit so that the driving unit rotates in two directions around the rotating shaft; and the program module is connected with the detection module and the infusion module and controls the output of the power unit force so as to control the infusion module to infuse the insulin with the currently required dosage.

According to one aspect of the invention, the driving wheel comprises at least two sub-wheels.

According to one aspect of the invention, the driving wheel comprises two sub-wheels, the rotating shaft is arranged between the two sub-wheels, two sides of the driving unit are respectively provided with one or more driving parts, and each sub-wheel is matched with at least one driving part.

According to one aspect of the present invention, two driving parts are respectively disposed at both sides of the driving unit, and the two driving parts located at one side of the driving unit are disposed up and down or disposed left and right.

According to one aspect of the invention, the power unit comprises an electrically heated linear drive or an electrically driven linear drive.

According to one aspect of the invention, the drive unit has a plurality of different rotational amplitudes or rotational rates and the infusion module has a plurality of different unit infusion amounts or infusion rates.

According to one aspect of the invention, two of the detection module, the program module and the infusion module are connected to each other to form an integral structure and are respectively adhered to different positions of the skin with the third module.

According to one aspect of the invention, the detection module, the program module and the infusion module are connected to form an integral structure and are adhered to the same position of the skin.

Compared with the prior art, the technical scheme of the invention has the following advantages:

in the bilateral drive closed-loop artificial pancreas disclosed by the invention, the power unit applies acting force in two directions to the drive unit, so that the drive unit rotates in two directions around the rotating shaft. The drive unit can drive the drive wheel to rotate to carry out insulin infusion in the rotation homoenergetic of two directions, has improved the infusion efficiency of artifical pancreas. In addition, the rotation of the drive unit in both directions also increases the drive mode of the drive unit, thereby increasing the infusion mode of the infusion module.

Further, the drive unit has a plurality of different rotational amplitudes or rotational rates and the infusion module has a plurality of different unit infusion amounts or infusion rates. Under the control action of the program unit, the power unit controls the driving unit to rotate by different amplitudes, and the infusion module has various different unit infusion amounts; meanwhile, the driving unit can also have various different rotation rates, so that the infusion rate of the infusion module is changed, and according to the physical condition, a user can select different infusion modes, optimize the infusion process and accurately control the blood sugar level.

Furthermore, the detection module, the program module and the infusion module are connected to form an integral structure and are stuck to the same position of the skin. The three modules are connected into a whole and are pasted at the same position, so that the number of the skin pasting devices of a user is reduced, and the interference of pasting more devices on the stretching of the user activity is further weakened; meanwhile, the problem of unsmooth wireless communication between the separation devices is effectively solved, and user experience is further enhanced.

Drawings

FIG. 1 is a schematic diagram of a bilateral drive closed-loop artificial pancreas module according to an embodiment of the present invention;

FIGS. 2 a-2 b are schematic diagrams of the internal structure of an infusion module according to one embodiment of the invention;

FIG. 3a is a schematic structural diagram of a driving unit according to an embodiment of the present invention;

FIG. 3b is a side view of the drive unit of FIG. 3 a;

FIG. 4 is a schematic illustration of different rotational amplitudes of a drive unit according to one embodiment of the present invention;

fig. 5 a-5 b are schematic structural views of a driving unit including two driving parts according to another embodiment of the present invention.

Detailed Description

As mentioned above, the driving mode of the artificial pancreas in the prior art for infusing the medicine is single, the infusion efficiency is low, and the user experience is poor.

The research finds that the reasons causing the problems are as follows: the driving unit can drive the driving wheel to rotate only by rotating in one direction, and the infusion mode is single.

In order to solve the problem, the invention provides the bilateral drive closed-loop artificial pancreas, the drive unit of the closed-loop artificial pancreas can drive the drive wheel to rotate in two different rotation directions, the infusion mode is diversified, the infusion efficiency is high, and the user experience is enhanced.

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be understood that the relative arrangement of parts and steps, numerical expressions, and numerical values set forth in these embodiments should not be construed as limiting the scope of the present invention unless it is specifically stated otherwise.

Further, it should be understood that the dimensions of the various elements shown in the figures are not necessarily drawn to scale, for example, the thickness, width, length or distance of some elements may be exaggerated relative to other structures for ease of illustration.

The following description of the exemplary embodiment(s) is merely illustrative and is not intended to limit the invention, its application, or uses in any way. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail herein, but are intended to be part of the specification as applicable.

It should be noted that like reference numerals and letters refer to like items in the following figures, and thus, once an item is defined or illustrated in one figure, further discussion thereof will not be required in the subsequent figure description.

FIG. 1 is a schematic diagram of a relationship between a single-side-driven closed-loop artificial pancreas modules according to an embodiment of the present invention.

The single-side driven closed-loop artificial pancreas of the embodiment of the invention mainly comprises a detection module 100, a program module 101 and an infusion module 102.

The detection module 100 is used to continuously detect a user's real-time blood glucose level parameters. In the embodiment of the present invention, the detecting module 100 is a Continuous Glucose Monitoring (CGM) capable of detecting a blood Glucose value in real time, Monitoring blood Glucose changes, and sending real-time blood Glucose data to the program module 101.

The program module 101 can receive the blood glucose parameter signal from the detection module 100 and is used to control the detection process of the detection module 100 and record the infusion information and the operation status of the infusion module 102. For example, when the blood glucose information detected by the detection module 100 after the end of life is inaccurate, the program module 101 may issue a stop detection instruction to the detection module 100. For another example, when the infusion module 102 becomes occluded with insulin, the program module 101 may record the occlusion condition and provide feedback to the user in a timely manner to eliminate potential safety hazards. Thus, the program module 101 is connected to the detection module 100 and the infusion module 102, respectively (where the connection includes a conventional electrical or wireless connection).

The infusion module 102 includes the necessary mechanical structure for infusing insulin and is controlled by the program module 101, as described in more detail below. The infusion module 102 infuses the currently required insulin into the user in accordance with the current insulin infusion amount data issued by the program module 101.

Embodiments of the present invention do not limit the specific locations and connections of the detection module 100, the program module 101, and the infusion module 102, as long as the aforementioned functional conditions are satisfied.

As in one embodiment of the present invention, the three are connected to form a unitary structure. Therefore, the three are stuck on the same position of the skin of the user. The three modules are connected into a whole and are pasted at the same position, so that the number of the skin pasting devices of a user is reduced, and the interference of pasting more devices on the stretching of the user activity is further weakened; meanwhile, the problem of unsmooth wireless communication between the separation devices is effectively solved, and user experience is further enhanced.

As in another embodiment of the present invention, the program module 101 and the infusion module 102 are interconnected to form a unitary structure, while the detection module 100 is provided separately in another structure. At this time, the detection module 100 and the program module 101 transmit wireless signals to each other to achieve connection with each other. Thus, the program module 101 and the infusion module 102 are affixed to a certain location of the user's skin, while the detection module 100 is affixed to another location of the user's skin.

As in yet another embodiment of the present invention, program module 101 and detection module 100 are interconnected to form the same device, while infusion module 102 is provided separately in another configuration. Infusion module 102 and program module 101 transmit wireless signals to each other to enable connectivity. Thus, the program module 101 and the detection module 100 may be affixed to a certain location of the skin of the user, while the infusion module 102 may be affixed to other locations of the skin of the user.

In another embodiment of the present invention, the three components are disposed in different structures. Therefore, the three are respectively stuck on different positions of the skin of the user. At this time, the program module 101 and the detection module 100 and the infusion module 102 respectively transmit wireless signals to each other to realize connection with each other.

It should be noted that the program module 101 according to the embodiment of the present invention also has functions of storing, recording, and accessing a database, and therefore, the program module 101 can be reused. Therefore, the physical condition data of the user can be stored, and the production cost and the consumption cost of the user are saved. As described above, when the detection module 100 or the infusion module 102 expires, the program module 101 may be separate from the detection module 100, the infusion module 102, or both the detection module 100 and the infusion module 102.

Generally, the detection module 100, the program module 101, and the infusion module 102 have different lifetimes. Therefore, when the three are electrically connected with each other to form the same device, the three can be separated from each other two by two. If a module is first terminated, the user can only replace the module and keep the other two modules for continuous use.

Here, it should be noted that the program module 101 of the embodiment of the present invention may further include a plurality of sub-modules. Different sub-modules may be respectively arranged in different structures according to the functions of the sub-modules, and there is no specific limitation as long as the corresponding functional conditions can be satisfied.

Fig. 2a is a schematic view of the internal structure of an infusion module according to an embodiment of the present invention. Fig. 2b is a schematic perspective view of the driving unit 1100 and the driving wheel 1130 according to the embodiment of the present invention.

The infusion module includes a drive unit 1100, a drive wheel 1130, a drug storage unit 1150, a plunger 1160, a screw 1170, and a power unit 1180.

The screw 1170 is connected to the piston 1160 and the drive wheel 1130, respectively. In the present embodiment, the driving wheel 1130 is movably disposed on the device base (not shown), and the driving wheel 1130 moves by rotating the pushing screw 1170, thereby pushing the piston 1160 disposed in the drug storage unit 1150 to move forward, so as to achieve the purpose of injecting insulin.

The driving unit 1100 is used to drive the driving wheel 1130 to rotate. The driving unit 1100 is movably connected to the apparatus base by a rotating shaft 1120. The power unit 1180 serves to apply a force to the driving unit 1100, so that the driving unit 1100 rotates. In the embodiment of the present invention, the power unit 1180 is fixedly connected to the top portion 1140 of the driving unit 1100, so as to divide the power unit 1180 into a left portion and a right portion, such as the portion in the direction of a 'and the portion in the direction of B' in fig. 2a, and further to alternately pull the driving unit 1100 to rotate around the rotating shaft 1120 in the directions of a 'and B'. Specifically, in the present embodiment, when the power unit 1180 pulls the driving unit 1100 in the a' direction, the driving unit 1100 rotates in the a direction around the rotation shaft 1120. When the power unit 1180 pulls the driving unit 1100 in the B' direction, the driving unit 1100 rotates in the B direction about the rotation shaft 1120. By alternately pulling the drive unit 1100 in the a 'direction and the B' direction, the drive unit 1100 can be alternately rotated in two different directions A, B about the rotation shaft 1120.

The power unit 1180 includes an electric heating type linear driver or an electric driving type linear driver. Specifically, in the present embodiment, the power unit 1180 is a shape memory alloy. The a 'direction portion and the B' direction portion of the shape memory alloy are alternately turned on and off, and thus a force is applied to the driving unit 1100 by a change in length thereof. The power unit 1180 may be formed of a continuous shape memory alloy, or may be formed of two left and right sections (e.g., a 'direction section and a B' direction section) of shape memory alloy, which is not particularly limited as long as the condition for applying force to rotate the driving unit 1100 is satisfied.

Here, it should be noted that the power unit 1180 includes, but is not limited to, a shape memory alloy, in other embodiments of the present invention, the power unit 1180 may have other structures, and the position where the power unit 1180 applies force to the driving unit 1100 is not limited to the top position 1140 of the driving unit 1100, as long as the condition for rotating the driving unit 1100 alternately left and right is satisfied.

As shown in fig. 2a, 2b, the drive unit 1100 further comprises more than two drive sections 1110. The driving wheel 1130 includes a plurality of sub-wheels, the circumferential surfaces of which are provided with gear teeth 1131. The drive unit 1100 is engaged with the drive wheel 1130 via gear teeth 1131.

In the embodiment of the present invention, the driving parts 1110 are respectively disposed at both sides of the driving unit 1100. Therefore, a plurality of sub-wheels are also respectively disposed at both sides of the driving unit 1100 to be used in cooperation with the driving part 1110. Specifically, in the embodiment of the present invention, the driving unit 1100 includes 4 driving parts 1110, 1110a, 1110b, 1110c, and 1110d, respectively. 1110a and 1110b are disposed on one side of the driving unit 1100, and 1110c and 1110d are disposed on the other side of the driving unit 1100. The drive wheel 1130 includes two sub-wheels, one of which cooperates with 1110a, 1110b and the other of which cooperates with 1110c, 1110 d.

Fig. 3a and 3b are a schematic perspective view and a schematic side view of the driving unit 1100, respectively.

In the embodiment of the present invention, the two driving parts 1110 located at one side of the driving unit 1100 are disposed up and down. Here, the up-down arrangement refers to the up-down positional relationship representation shown in fig. 3 b. Specifically, two driving parts 1110 (e.g., 1110a and 1110b) on one side of the driving unit 1100 can be seen in a side view of fig. 3b, and 1110b and 1110d are blocked by 1110a and 1110c, respectively.

It should be noted that, in other embodiments of the present invention, the 4 driving portions may also be formed in other manners, for example, two driving portions on one side of the driving portion are disposed on the left and right sides, as long as the condition that the driving wheels are pushed to rotate in cooperation with each other can be satisfied, and the present invention is not limited in particular.

Fig. 4 is a schematic diagram of the position structure of the driving unit 1100 in multiple rotation ranges, and is also a top view in the direction of the arrow in fig. 3 b.

Throughout a single rotation of the driving unit 1100 in one direction, for example, the direction a, the driving part 1110a and/or 1110b pushes the cog 1131 to rotate the driving wheel 1130, and the cog 1110c and 1110d can slide on the cog 1131 without applying a force to push the driving wheel 1130 to rotate. And as is apparent, 1110c first slides to the next adjacent actuation position. At this time, the driving unit 1100 may stop rotating, the driving part 1110a and/or 1110b stops pushing the gear teeth 1131, and the driving wheel 1130 stops rotating. The drive unit 1100 accomplishes one rotation amplitude. At this time, the driving unit 1100 rotates to a direction a₁Location. The next moment the drive unit 1100 continues to rotate in direction a, 1110d will slide to the next adjacent drive position. The drive unit 1100 again accomplishes a range of rotation. At this time, the driving unit 1100 rotates to a₂Location. At this time, the driving unit 1100 completes the entire process of one rotation in the a direction, implementing a₁、A₂Two rotational amplitudes, thereby providing two-gear propulsion of the drive wheel 1130, the infusion module has two infusion modes. In another embodiment of the present invention, after the driving part 1110d slides to the driving position, the driving unit 1100 may further continue to rotate in the direction a, so that the driving part 1110d moves away from the driving position. The driving unit 1100 may also repeat the above process while rotating in the B direction.

It should be noted that, during the above rotation, 1110d may be slid to the next driving position first, and 1110c may be slid to the next driving position later, which is not limited herein. Similarly, when the driving unit 1100 rotates in the direction B, there is B₁、B₂Two types of rotorsAnd (4) dynamic amplitude.

Obviously, during the whole process of the single rotation of the driving unit 1100 in the direction a, the driving unit 1100 performs alternating rotation and stop rotation, the driving part 1110 alternately pushes and stops pushing the gear 1131, so that the driving wheel 1130 alternately rotates and stops rotating, and thus two-gear pushing of the driving wheel 1130 is realized, and the infusion module has two infusion modes.

Referring to fig. 4, in another embodiment of the present invention, the driving unit 1100 rotates a in the direction a₁The amplitude, in turn, may be rotated one or both amplitudes in the B direction until rotation in the B direction ceases. This process completes one rotation of the driving unit 1100 in both directions alternately, so that various modes of pushing can be performed on the driving wheel 1130. Thus, in embodiments of the present invention, the driving unit 1100 may be at A₁-B₁Amplitude range or A₁-B₁-B₂Amplitude range or B₁-A₁-A₂The amplitude ranges are alternated to switch the rotation amplitude to different infusion modes.

With continued reference to FIG. 4, in yet another embodiment of the present invention, the drive unit 1100 may also be rotated directly to A₂Gear position without passing through A₁And (4) gear positions. Then directly rotated to B₂Gear position without passing through B₁Gear, i.e. drive unit 1100 directly at A₂-B₂The gears are alternately rotated. As described above, the drive unit 1100 may also be at A₁-B₁The gears are alternately rotated.

By utilizing the infusion module of the embodiment of the invention, when infusion is started, the infusion amount of insulin is larger, and a patient or an artificial pancreas can select a large rotating gear A₂-B₂And (4) infusion. After a period of infusion, the intermediate rotary gear A can be used₁-B₁-B₂Or B₁-A₁-A₂Reducing the rate of insulin infusion. When insulin infusion is nearly completed, the patient can choose the small rotating gear A₁-B₁And (4) infusion, further reducing the infusion rate, and achieving accurate control of insulin infusion. Of course, suffer fromThe patient or the artificial pancreas may also select one or more of the modes for infusion, and is not particularly limited herein.

It should be noted that, in another embodiment of the present invention, more driving portions, such as 3, 4, etc., may be disposed on one side of the driving unit. The total number of the driving parts may also be an odd number, such as 3, 5 or more, i.e. the number of the driving parts on both sides of the driving unit is not equal. Correspondingly, the drive wheel 1130 includes more than two sub-wheels to accommodate different positions and numbers of drive portions 1110. And the structural relationship between the different driving portions may be similar to that described above, and is not particularly limited herein.

Fig. 5 a-5 b are schematic structural diagrams of a driving unit 1200 including two driving parts.

As described above, when the driving unit 1200 is acted by the force in the direction a', the driving unit 1200 rotates around the rotating shaft 1220 in the direction a, and the driving part 1210a pushes the gear teeth 1231a, thereby driving the driving wheel 1230a to rotate. When the driving unit 1200 is acted by a force in the direction B', the driving unit 1200 rotates around the rotating shaft 1220 in the direction B, and the driving part 1210B pushes the gear 1231B, thereby driving the driving wheel 1230B to rotate.

With continued reference to fig. 5a and 5B, after the driving portion 1210a or 1210B reaches a different position, the driving unit 1200 can still rotate in the direction a or the direction B to move the driving portion away from the driving position. If the driving part 1210a is away from the driving position by a distance s₁If the tooth pitch of the gear teeth is S, S₁1/3S, 1/2S, 3/4S or S, etc. Therefore, during the rotation of the driving unit 1200, at a certain moment, neither of the driving parts 1210a and 1210b pushes the gear teeth 1231, such as the front end of the driving part is separated from the driving position by s₂、s₃Distance. At this point, the drive wheel is not rotating and the infusion module does not perform insulin infusion. In this principle of operation, the drive unit 1200 will rotate by any of a variety of different magnitudes and the infusion module will have a variety of different infusion modes.

The embodiment of the invention can also change the rotation frequency of the driving unit by changing the frequency of the output power of the power unit, so that the infusion module has various different infusion rates. The user or the closed-loop artificial pancreas can flexibly select the appropriate infusion rate according to the needs, and the infusion process is also flexible and controllable.

In summary, the present invention discloses a bilateral-drive closed-loop artificial pancreas, wherein a drive unit of the closed-loop artificial pancreas can drive a drive wheel to rotate in two different rotation directions, so that the infusion mode is diversified, the infusion efficiency is improved, and the user experience is enhanced

Although some specific embodiments of the present invention have been described in detail by way of illustration, it should be understood by those skilled in the art that the above illustration is only for the purpose of illustration and is not intended to limit the scope of the invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.