专

一种导引延伸导管系统

KR66829W

发明人

康玲, 魏达, 熊洲, 昌盛

受让人

HUNAN AIPUTE MEDICAL EQUIP CO LTD (HUNA-Non-standard)

申请人

湖南红太阳新能源科技有限公司

申请号

000314

申请日

2017-07-05

公开(公告)号

KR66829W

公开(公告)日

1991-01-17

IPC分类号

F24D3/08F16K11/10F24D19/10F24D3/10F16K11/07

CPC分类号

优先权号

202121515593

优先权日

2021-07-04

摘要

The structure includes a main printed circuit board with first electronic devices having low heat generation. At least an auxiliary printed circuit board carries second electronic devices with high heat generation and connected with one edge of the main printed circuit board through a flexible printed circuit tape. A holder is fixed on the main printed circuit board for resiliently supporting the auxiliary printed circuit board at a distance above the former when the latter is turned over above the main printed circuit board by bending the flexible printed circuit tape.

A heat conductive surface of the second electronic device is exposed outside. A heat conductive unit is tightly brought into contact with the heat conductive surface of the second electronic device for transferring heat from the second electronic device to the outside.

ADVANTAGE -Even though there is a little height difference between respective electronic devices mounted on auxiliary printed circuit boards, this difference is absorbed by holder so that electronic devices can be always be brought into close contact with inner wall of housing with appropriate pressure.

权利要求

1. A method of limiting a combined signal, the method comprising: multiplying an information signal intended for each subscriber terminal by a spreading code and a weighting coefficient, which is proportional to the power of the transmission directed to the subscriber terminal; combining transmissions intended for various subscriber terminals into a combined signal; setting a threshold value for power or amplitude values of the combined signal; dividing a chip sequence of the combined signal into blocks; comparing the power or amplitude values of each block with the set threshold value to find out whether the combined signal needs to be limited; and when the threshold value is exceeded, decorrelating the block where the threshold value was exceeded and a pre-determined number of channelization codes, which have a pre-determined spreading factor, and performing normalization to determine first weighting coefficients for the channelization codes or channelization code groups, the first weighting coefficients being proportional to the power of transmissions directed to pre-determined subscriber terminals; comparing each combination of the first weighting coefficient and the related channelization code with set objectives and determining second weighting coefficients for downlink transmissions selected as a result of the comparison, the second weighing coefficients being proportional to the power of transmissions directed to pre-determined subscriber terminals; and re-forming the block using combinations of the channelization codes and the weighting coefficients that were determined, the weighting coefficients being second weighting coefficients provided that they have been determined, or otherwise first weighting coefficients, and thus the examined block of the combined signal becomes limited in respect of the power or amplitude.

2. A method according to claim 1 wherein all channelization codes that have the same pre-determined spreading factors are used in decorrelation.

3. A method according to claim 1 , wherein decorrelation is performed by calculating an input for vectors using the block where the threshold value was exceeded and a pre-determined number of channelization codes.

4. A method according to claim 1 , wherein the set objective is not to exceed the maximum value limit of the peak code domain error according to the standard of the telecommunications system used.

5. A method according to claim 1 , wherein the set objective is to keep the channelization codes orthogonal.

6. A method according to claim 1 , wherein the set objective is not to exceed the error vector magnitude according to the standard of the telecommunications system used.

7. A method according to claim 1 , wherein normalization is performed by dividing the decorrelation result by the spreading factor of the channelization code.

8. A method according to claim 1 , wherein the first and second weighting coefficients of the combined signal are defined for the codes.

9. A method according to claim 1 , wherein the first and second weighting coefficients of the combined signal are defined for the code groups.

10. A method of limiting a combined signal, the method comprising: multiplying an information signal intended for each subscriber terminal by a spreading code and a weighting coefficient, which is proportional to the power of the transmission directed to the subscriber terminal; combining transmissions intended for various subscriber terminals into a combined signal; setting a threshold value for the power or amplitude values of the combined signal; dividing a chip sequence of the combined signal into blocks; comparing the power or amplitude values of each block with the set threshold value to find out whether the combined signal needs to be limited; and when the threshold values is exceeded, forming a residual signal; searching for channelization codes that are unused at a given time; and decorrelating the residual signal and the unused channelization codes to determine weighting coefficients; forming an estimate of the residual signal by means of the unused channelization codes, the weighting coefficients and one or more vectors selected from the sum vectors corresponding to the unused channelization codes; forming a clipped signal by subtracting the estimate of the residual signal from the combined signal of the examined block, and thus the examined block of the combined signal becomes limited in respect of the power or amplitude.

11. A method according to claim 10 , wherein the combined signal is divided into chip blocks whose length is the same as the spreading factor of the channelization code.

12. A method according to claim 10 , wherein the threshold value is determined so that the desired peak-to-mean ratio of the power or amplitude is achieved.

13. A method according to claim 10 , wherein a signal to be added to the combined signal is an orthogonal signal.

14. A method according to claim 10 , wherein the unused codes are searched for by decorrelating the combined signal and the channelization codes and by normalizing the decorrelation result by dividing it by the channelization code length.

15. A method according to claim 10 , wherein a signal to be added to the combined signal is a non-orthogonal signal.

16. A method according to claim 10 , wherein the residual signal is formed by determining a residual value for each chip of a block as follows: if the chip value is greater than the threshold value, the threshold value is subtracted from the chip and the result of this subtraction is the residual value; if the absolute value of the chip at most equals to the threshold value, the residual value is zero; if the chip value is lower than the negation of the threshold value, the threshold value is added to the chip value and the result of this addition is the residual value.

17. A method according to claim 10 , wherein the estimate of the residual signal is formed by multiplying each unused channelization code and the corresponding weighting factor and by adding up the products obtained.

18. A method according to claim 10 , wherein the estimate of the residual signal is formed by first determining a partial estimate by multiplying each unused channelization code and the corresponding weighting coefficient to obtain an input vector and by adding the selected sum vector to the input vector obtained, after which the partial estimates that were determined are added up.

19. A method according to claim 10 , wherein the residual signal is formed by determining a residual value for each chip of the block as follows: if the chip value is at least zero, the standard deviation of the combined signal is subtracted from the chip value and the result of this subtraction is the residual value; if the chip value is lower than zero, the standard deviation of the combined signal is added to the chip value and the result of this addition is the residual value.

20. A method according to claim 10 , wherein the sum vector is selected so that all elements are zeroes.

21. A method according to claim 10 , wherein the sum vector is selected so that the sum vector comprises at least one element that is different from zero.

22. A transmitter of a radio telecommunications system where a combined signal is limited and an information signal intended for each subscriber terminal is multiplied by a spreading factor and a weighting coefficient, which is proportional to the power of the transmission directed to the subscriber terminal, and transmissions directed to several different subscriber terminals are combined into a combined signal, the transmitter comprising: a setting unit configured to set a threshold value for the power or amplitude values of the combined signal; a dividing unit configured to divide the chip sequence of the combined signal into blocks; a comparing unit configured to compare the power or amplitude values of each block with the set threshold value to find out whether the combined signal needs to be limited; a decorrelating unit configured to decorrelate the block where the threshold value was exceeded and a pre-determined number of channelization codes, which have a pre-determined spreading factor, and for performing normalization to determine first weighting coefficients for the channelization codes or channelization code groups, the first weighting coefficients being proportional to the power of the transmissions directed to pre-determined subscriber terminals; a second comparing unit configured to compare each combination of a first weighting coefficient and a related channelization code with set objectives and for determining second weighting coefficients for downlink transmissions selected as a result of the comparison, the second weighting coefficients being proportional to the power of the transmissions directed to pre-determined subscriber terminals; and a re-forming unit configured to re-form the block using combinations of the channelization codes and the weighting coefficients that were determined, the weighting coefficients being second weighting coefficients provided that they have been determined, or otherwise first weighting coefficients, and thus the examined block of the combined signal becomes limited in respect of the power or amplitude.

23. A transmitter according to claim 22 , wherein all channelization codes that have the same pre-determined spreading factors are used in decorrelation.

24. A transmitter according to claim 22 , wherein decorrelation is performed by calculating an input for vectors using the block where the threshold value was exceeded and a pre-determined number of channelization codes.

25. A transmitter according to claim 22 , wherein the combined signal is divided into chip blocks whose length is the same as the spreading factor of the channelization code.

26. A transmitter according to claim 22 , wherein the set objective is not to exceed the maximum value limit of the peak code domain error according to the standard of the telecommunications system used.

27. A transmitter according to claim 22 , wherein the set objective is to keep the channelization codes orthogonal.

28. A transmitter according to claim 22 , wherein the set objective is not to exceed the error vector magnitude according to the standard of the telecommunications system used.

29. A transmitter according to claim 22 , wherein the threshold value is determined so that the desired peak-to-mean ratio of the power or amplitude is achieved.

30. A transmitter according to claim 22 wherein normalization is performed by dividing the decorrelation result by the spreading factor of the channelization code.

31. A transmitter according to claim 22 , wherein the first and second weighting coefficients of the combined signal are determined for the codes.

32. A transmitter according to claim 22 , wherein the first and second weighting coefficients of the combined signal are determined for the code groups.

33. A transmitter of a radio telecommunications system where a combined signal is limited and an information signal intended for each subscriber terminal is multiplied by a spreading factor and a weighting coefficient, which is proportional to the power of the transmission directed to the subscriber terminal, and transmissions directed to several different subscriber terminals are combined into a combined signal, the transmitter comprising: a setting unit configured to set a threshold value for the power or amplitude values of the combined signal; a dividing unit configured to divide the chip sequence of the combined signal into blocks; a comparing unit configured to compare the power or amplitude values of each block with the set threshold value to find out whether the combined signal needs to be limited; a forming unit configured to form a residual signal; a searching unit configured to search for the channelization codes that are unused at a given time and for decorrelating the residual signal and the unused channelization codes to determine weighting coefficients; a selecting unit configured to select one or more desired vectors from the sum vectors corresponding to the unused channelization codes; an estimating unit configured to form an estimate of the combined signal by means of the unused channelization codes and the selected one or more sum vectors; a second forming unit configured to form a clipped signal by subtracting the estimate of the residual signal from the combined signal of the examined block, and thus the examined block of the combined signal becomes limited in respect of the power or amplitude.

34. A transmitter according to claim 33 , wherein a signal to be added to the combined signal is an orthogonal signal.

35. A transmitter according to claim 33 , wherein the unused codes are searched for by decorrelating the combined signal and the channelization codes and by normalizing the decorrelation result by dividing it by the channelization code length.

36. A transmitter according to claim 33 , wherein the residual signal is formed by determining a residual value for each chip of a block as follows: if the chip value is greater than the threshold value, the threshold value is subtracted from the chip and the result of this subtraction is the residual value; if the absolute value of the chip at most equals to the threshold value, the residual value is zero; if the chip value is lower than the negation of the threshold value, the threshold value is added to the chip value and the result of this addition is the residual value.

37. A transmitter according to claim 33 , wherein the estimate of the residual signal is formed by multiplying each unused channelization code and the corresponding weighting factor and by adding up the products obtained.

38. A transmitter according to claim 33 , wherein the estimate of the residual signal is formed by first determining a partial estimate by multiplying each unused channelization code and the corresponding weighting coefficient to obtain an input vector and by adding the selected sum vector to the input vector obtained, after which the partial estimates that were determined are added up.

39. A method according to claim 33 , wherein the residual signal is formed by determining a residual value for each chip of the block as follows: if the chip value is at least zero, the standard deviation of the combined signal is subtracted from the chip value and the result of this subtraction is the residual value; if the chip value is lower than zero, the standard deviation of the combined signal is added to the chip value and the result of this addition is the residual value.

40. A transmitter according to claim 33 , wherein all elements of the selected sum vector are zeroes.

41. A transmitter according to claim 33 , wherein each selected sum vector includes at least one element that is different from zero.

42. A transmitter according to claim 33 , wherein the signal to be added to the combined signal is a non-orthogonal signal.

43. A transmitter of a radio telecommunications system where a combined signal is limited and an information signal intended for each subscriber terminal is multiplied by a spreading factor and a weighting coefficient, which is proportional to the power of the transmission directed to the subscriber terminal, and transmissions directed to several different subscriber terminals are combined into a combined signal, the transmitter comprising: means for setting a threshold value for the power or amplitude values of the combined signal, means for dividing the chip sequence of the combined signal into blocks, means for comparing the values of each block with the set threshold value to find out whether the combined signal needs to be limited, means for decorrelating the block where the threshold value was exceeded and a pre-determined number of channelization codes, which have a pre-determined spreading factor, and for performing normalization to determine first weighting coefficients for the channelization codes or channelization code groups, the first weighting coefficients being proportional to the power of the transmissions directed to pre-determined subscriber terminals, means for comparing each combination of a first weighting coefficient and a related channelization code with the set objectives and for determining second weighting coefficients for downlink transmissions selected as a result of the comparison, the second weighting coefficients being proportional to the power of the transmissions directed to pre-determined subscriber terminals, means for re-forming the examined block using combinations of the channelization codes and the weighting coefficients that were determined, the weighting coefficients being second weighting coefficients provided that they have been determined, or otherwise first weighting coefficients, and thus the examined block of the combined signal becomes limited in respect of the power or amplitude.

44. A transmitter of a radio telecommunications system where a combined signal is limited and an information signal intended for each subscriber terminal is multiplied by a spreading factor and a weighting coefficient, which is proportional to the power of the transmission directed to the subscriber terminal, and transmissions directed to several different subscriber terminals are combined into a combined signal, the transmitter comprising: means for setting a threshold value for the power or amplitude values of the combined signal, means for dividing the chip sequence of the combined signal into blocks, means for comparing the values of each block with the set threshold value to find out whether the combined signal needs to be limited, means for forming a residual signal, means for searching for the channelization codes that are unused at a given time and for decorrelating the residual signal and the unused channelization codes to determine weighting coefficients, means for selecting one or more desired vectors from the sum vectors corresponding to the unused channelization codes, means for forming an estimate of the combined signal by means of the unused channelization codes and the selected one or more sum vectors, means for forming a clipped signal by subtracting the estimate of the residual signal from the combined signal of the examined block, and thus the examined block of the combined signal becomes limited in respect of the power or amplitude.

说明书

[0001]FIELD OF THE INVENTION

[0002]This invention relates to systems and methods for producing medical devices.

[0003]BACKGROUND OF THE INVENTION

[0004]Many indwelling medical devices have a hollow portion. For example, stents are hollow devices that are inserted into body ducts for preventing narrowing of the duct lumen, for tutoring a dilated lumen or for acting as a substrate for tissue growth. As another example, a catheter may have a hollow portion that may serve to transfer a fluid from outside the body to a body cavity, or for draining fluid from a body cavity. As yet another example, an artificial blood vessel valve has a casing enclosing a space through which blood flows.

[0005]International Patent Publication WO03/099166 discloses an indwelling unravable medical device having a hollow portion, such as a stent. The device has a generally helical seam which is a weakened region in the wall of the device. When it is desirable to remove the indwelling device from the body, an end of the device is grasped and pulled. As the end is pulled, the seam splits so that the device is removed as a slender strip of material.

[0006]U.S. Pat. No. 8,119,151 to Heidner et al discloses a method for coating portions of a medical device. A layer of coating is applied to a surface of a medical device with an applicator. While the coating is being applied, the spreader is positioned in contact with the coating to reduce the coating thickness by spreading the coating over a larger surface area of the target surface.

[0007]US Patent Publication 20120029616 of Guerriero et al discloses a method of coating a stent in which the flow rate of a coating material sprayed onto the stent is varied while axially moving the stent. The stent repeatedly passes from one end of the stent to another relative to a major axis of the stent adjacent to a fixed or movable spray nozzle. The axial speed may be varied during spraying of the stent based on the modified flow rate of the coating material to deposit a selected amount of coating material per pass.

[0008]U.S. Pat. No. 7,959,999 to Prabhu discloses a stent formed by encasing or encapsulating metallic rings in an inner polymeric layer and an outer polymeric to layer. At least one polymer link connects adjacent metallic rings. The stent is drug loaded with one or more therapeutic agents or drugs.

[0009]US Patent Publication 20090259294 to Cully et al discloses a removable device such as a stent-graft, intended for applications where it may be desirable to remove the device at some time following implantation. The stent-graft includes a helically-wound stent provided with a covering of graft material. It is removable by gripping an end of the helically-wound stent component with a retrieval device and applying tension to the stent component in the direction in which it is intended to be withdrawn from the site of implantation.

[0010]US Patent Publication 20090192593 to Meyer et al discloses implantable medical devices, such as a stent, for delivering a therapeutic agent, and methods for making such medical devices. In one embodiment, the medical device comprises a stent having a plurality of struts, at least one of which has a cavity disposed therein. A therapeutic agent is delivered from the cavity through and opening in a strut surface.

[0011]SUMMARY OF THE INVENTION

[0012]The present invention provides a system and method for manufacturing a stent. The system of the invention includes a mandrel and a micromanipulator that generates a longitudinal movement and a rotational movement of the mandrel. The system also includes a spraying device that sprays a polymeric coating material such as a polymeric suspension onto the mandrel During spraying of the polymeric suspension onto the mandrel, the mandrel is manipulated by a micromanipulator to produce a continuous coating on the mandrel not having any holes or breaks therein. At least one of the flow rate of the liquid streams, the width of the liquid streams, a velocity of the linear movement of the mandrel and a rotational velocity of the mandrel is varied during manipulation of the mandrel, so that a continuous coating is produced having a non-constant thickness. The polymeric coating is allowed to cure on the mandrel to form the stent, which is then removed from the mandrel.

[0013]In one embodiment of the invention, the mandrel is manipulated to produce a stent having a helical groove on the outer surface of the stent. The helical groove is a weakened region in the stent that forms a tear line. When it is desired to remove the stent from the body, the end of the stent can be grasped by a grasping device and pulled. As the end is pulled, the tear line splits so that the stent is removed from the body as a slender strip.

[0014]In the manufacture of a medical device by the method of the invention, application of the polymer suspension to the filament may be carried out in a single application step, as described above. Alternatively, two or more application steps may be used, in which at least one of the applications involves spraying polymer suspension, using the system of the invention. For example, a first coat may be sprayed onto the mandrel producing a coating having a smooth outer surface, and then a second coat may be applied having a grooved outer surface. As another example, a first coat of polymer suspension may be applied by dipping the mandrel and filament into a polymer suspension, and then spraying a second coat using the system of the invention. When more than one polymer applications are used, the different coats may be from the same material or from different materials.

[0015]After formation of the stent of the medical device, the device may be adapted, for example, to contain one or more drugs that are released over time after deployment of the device in the body. For example, a small region of the polymer can be removed and replaced with a plug contain the drug or drugs to be released.

[0016]Thus, in one of its aspects, the present invention provides a system for manufacturing a stent comprising:

[0017](a) a spraying device configured to deliver one or more liquid streams, each liquid stream having a flow rate and a width; (b) a mandrel having a longitudinal axis; (c) a micromanipulator configured to grasp the mandrel and to manipulate the mandrel in the liquid streams; and (d) a processor configured to (a) activate the micromanipulator to manipulate the mandrel in the one or more liquid streams according to a predetermined pattern of movement of the mandrel, the predetermined pattern of movement having a linear movement of the mandrel along the longitudinal axis and further having a rotational movement of the mandrel around the longitudinal axis; and (b) activate the spraying device to spray the one or more liquid streams onto the mandrel as the mandrel is being manipulated in the liquid streams to form a continuous coating over the mandrel; wherein at least one of the flow rate of the liquid streams, the width of the liquid streams, a velocity of the linear movement of the mandrel and a rotational velocity of the mandrel is varied during manipulation of the mandrel.

[0018]The system of the invention may further comprise a glove box.

[0019]The spraying device may be provided with a focusing mechanism that allows selection of the spray width. The spraying device may comprise an atomizer. The spraying device may be configured to spray a polymer suspension.

[0020]The processor may be configured, for example, to manipulate the mandrel during spraying to produce a stent having a helical groove in the continuous coating. The processor may be configured to fill the helical groove with a polymer solution. The processor may be configured to repeat the step of spraying one or more liquid streams one or more additional times.

[0021]In another of its aspects, the invention provides a method for manufacturing a stent comprising:

[0022](a) spraying one or more polymer solutions onto a mandrel, each liquid stream having a flow rate and a width; (b) manipulating the mandrel in the one or more liquid streams according to a predetermined pattern of movement of the mandrel to produce a continuous coating of the polymer solutions on the mandrel, the predetermined pattern of movement having a linear movement of the mandrel along a longitudinal axis of the mandrel and further having a rotational movement of the mandrel around the longitudinal axis; (c) varying at least one of the flow rate of the liquid streams, the width of the liquid streams, a velocity of the linear movement of the mandrel and a rotational velocity of the mandrel during manipulation of the mandrel; (d) allowing the one or more polymer solutions to cure on the mandrel and produce the stent; and (e) removing the stent from the mandrel.

[0023]The step of spraying the one or more polymer solutions onto the mandrel may be repeated one or more additional times. A filament may be embedded in the continuous coating. The filament may be fashioned, for example, into a helix or an undulating helix.

[0024]The mandrel may be manipulated in the polymer streams to produce a continuous coating having a helical groove. The helical groove may be filled with a second polymer solution.

[0025]One or more drugs may be incorporated into the stent.

[0026]BRIEF DESCRIPTION OF THE DRAWINGS In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: FIG. 1 shows a system for producing a stent in accordance with one embodiment of the system invention; FIG. 2 shows a stent in accordance with one embodiment of the method of the invention; FIG. 3 shows an intermediate step in the production of another stent by the to method of the invention; FIG. 4 a shows the stent of FIG. 3 in a perspective view after completion and FIG. 4 b shows the stent of FIG. 3 in longitudinal section after completion; FIG. 5 a shows an intermediate step in the production of another stent by the method of the invention; and FIG. 5 b shows the stent of FIG. 5 a in a perspective view after completion.

[0027]DETAILED DESCRIPTION OF EMBODIMENTS

[0028]FIG. 1 shows a system 1 for producing a medical device having an unravable portion in accordance with one embodiment of the invention. The system 1 includes a mandrel 4 .

[0029]The system 1 also includes a micromanipulator 8 . The mandrel 4 is mounted into a chuck 6 of the micromanipulator 8 . The micromanipulator 8 is under the control of a programmable processor 10 which is configured to manipulate the mandrel 4 as explained below. The micromanipulator 8 can generate a longitudinal movement of the mandrel 4 , as well as rotational movement.

[0030]The system 1 further includes an atomizer 14 . The mandrel 4 mounted in the chuck 6 is positioned under a nozzle 12 of the atomizer 14 . The atomizer 14 applies a coating material such as a polymeric suspension onto the mandrel in the form of an atomized stream 16 of the suspension. The atomizer may be, for example, the AccuMist system of Sono-Tek. In the AccuMist system, an ultrasonically produced spray of the polymeric suspension is produced at the tip of the nozzle 12 and is immediately entrained in a low pressure air stream (typically about 1 psi) from a second nozzle 18 . An adjustable focusing mechanism (not shown) allows selection of the spray width which may be, for example, as small as 0.25 mm. The atomizer 14 is also under the control of the processor 10 , so that the spraying of the polymer suspension can be coordinated with the manipulation of the mandrel 4 by the micromanipulator 8 .

[0031]The system 1 is preferably enclosed in a glove box (not shown), in order to isolate the system from external factors such as vibrations and drafts, while allowing a user to monitor the manufacturing process. A low-velocity exhaust (not to shown) may be used to maintain a negative air pressure in the glove-box to remove unwanted polymer suspension beyond the target area.

[0032]The coating material may be a polymer such as a urethane, polycarbonate, silicone, or styrene. The solvent of the polymer suspension may be, for example, THF, acetone, DMAC, toluene, or chloroform. After curing of the polymer suspension, the completed stent 26 is removed from the mandrel 4 , as shown in FIG. 4 . The coating material may be a biodegradable material.

[0033]During spraying of the polymeric suspension onto the mandrel 4 , the mandrel 4 is manipulated by the micromanipulator 8 under the control of the processor 10 in order to produce a coating on the mandrel 4 .

[0034]In one embodiment of the invention, the processor 10 is configured to manipulate the mandrel 4 during spraying of the polymeric suspension so as to produce a stent 26 shown in FIG. 2 , having a coating 20 on the mandrel 4 having a surface topography in which there is a shallow helical groove 22 . The helical groove 22 in the polymer layer 20 is a weakened region in the coating 20 that forms a tear line that allows the stent to be unraveled by grasping an end 30 of the stent 26 and pulling on the end. When it is desired to remove the stent 22 from the body, the end 30 of the stent can be grasped by a grasping device and pulled. As the end is pulled, the tear line 22 splits so that the stent is removed from the body as a slender strip.

[0035]In the manufacture of a medical device by the method of the invention, application of the polymer suspension to the filament may be carried out in a single application step, as described above. Alternatively, two or more application steps may be used, in which at least one of the applications involves spraying polymer suspension, using the system of the invention. For example, a first coat may be sprayed onto the mandrel producing a coating having a smooth outer surface, and then a second coat may be applied having a grooved outer surface. As another example, a first coat of polymer suspension may be applied by dipping the mandrel and filament into a polymer suspension, and then spraying a second coat using the system of the invention. When more than one polymer applications are used, the different coats may be from the same material or from different materials.

[0036]In another embodiment of the invention, shown in FIGS. 3 and 4 , a first coating 50 is applied to the mandrel 4 having a smooth outer surface. After curing of the first coating 50 , a flexible filament 2 is mounted onto the mandrel 4 over the first coating in a desired shape. The filament may be for example a metal wire from stainless steel or a nickel-titanium alloy (Nitinol). The filament may be made from a biodegradable material. In FIG. 3 , the filament 2 has been fashioned into a helix. The wire may also be fashioned into an undulating helix, as disclosed in WO03/099166. A second coating material 52 is then applied over the first coating material that bonds to the first coating material so that the filament 2 becomes embedded between the two coatings. The outer coating 20 has a surface topography in which there is a shallow helical groove 22 with the filament running parallel to the groove that forms a helical tear line. The stent 26 is shown in a perspective view in FIG. 4 a and in longitudinal section in FIG. 4 b . This process produces a stent 54 shown in perspective view in FIG. 4 a , and in longitudinal cross-sectional view in FIG. 4 b.

[0037]FIG. 5 shows a method for producing an unravable stent in accordance with another embodiment of the invention. As shown in FIG. 5 a , a first coating material such as a polymer suspension is applied to the mandrel 4 so as to form a coating 40 of the mandrel in which a groove 42 is present. A filament may or may not be embedded in the coating 40 . The groove 42 may be completely devoid of the coating material, as shown in FIG. 5 a , so that after formation of the coating 40 the mandrel 4 is exposed in the grooves 42 . Alternatively, the groove may contain a thin layer of the coating so that the thickness of the coating is thinner in the grooves. Then, as shown in FIG. 5 b , a second material 44 is sprayed into the grooves 42 . The second material 44 is selected to be weaker than the first material 40 . A stent 46 is thus formed in which the second material 44 forms a helically shaped tear line. The tear line can be detached by pulling on an end of the stent 46 , as explained above.

[0038]After formation of the stent of the medical device, the device may be adapted, for example, to contain one or more drugs that are released over time after deployment of the device in the body. For example, a small region of the polymer can be removed and replaced with a plug contain the drug or drugs to be released.

同族专利

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