fig1 shows a very basic structure of a prior art subcutaneous medical implant device . implant disc 2 consists of a top 4 , a bottom 6 and an outside wall 8 . it also has an opening 10 that is used for drug delivery . the size of opening 10 and the number of openings may vary . line 2 - 2 will be used in the remaining figures to illustrate various internal structures of the prior art implants and of the improved implants disclosed in this application . however , please understand that these figures are not intended to cover all of applicant &# 39 ; s improved implant structures . in addition , for example , the figures are not representative of the number of layers of materials in an implant . also , although the matrix materials are shown in regular shapes , they need not have such a regular shape — e . g ., the channel may have a curved or irregular shape , and it have different heights / widths ( such as lower / narrower near the opening and expanded / broader thereafter , or vice versa ). in that regard , the preferred 3 - d printing process is believed to provide , inter alia , the capability and flexibility to design different matrix channel shapes , sizes , designs , et cetera . if non - 3 - d printing processes ( such as extrusion ) are used to make the matrix , the channels and barriers are likely to be more arbitrarily configured . nevertheless , non - 3 - d processes ( such as hot - melt casting , extrusion and shrink wrap ) may be used in the formation of some ( or all ) of the improved implant . fig1 shows a generally cylindrical implant device . however , the shape of the implant in this embodiment ( and in all other embodiments ) may be modified to whatever shape is desirable . in other words , a particular exterior shape of the implant is not critical to the improved implant of this application . in looking at the figures , it should be borne in mind that the structures are not drawn to scale . instead , they are drawn in a manner to illustrate the general subject matter of this application . thus , the relative sizes / shapes / dimensions of the coating , matrix materials , matrix channels , matrix barrier materials , drug materials , anticoagulant channels / materials and the like are not intended to be realistic . fig2 shows the very basic structure of the prior art implant along line 2 - 2 of fig1 . more specifically , an impermeable coating 12 generally surrounds matrix 14 . in that regard , the coating must be impermeable in terms of ( a ) prohibiting the flow of drug materials and ( b ) having a relatively high breaking strength . opening 10 extends all of the way through implant 2 . as a result , edges of the coating and matrix create sidewalls 16 to the opening . although the opening in this and all other embodiments is shown to extend entirely through the implant , this is not always necessary . moreover , it should be understood that there may be one or more openings that extend fully or only partially through the implant . circle 18 in fig2 will be used in illustrate the applicant &# 39 ; s embodiments disclosed below in fig3 to 7 . circle 18 is intended to create a somewhat microscopic view of a portion of the improved implant so as to help explain some of the structures , functions and purposes of the subject matter of this application . more specifically , in one possible situation , the matrix is surrounded by an impervious coating . the matrix is comprised of , inter alia , at least one ( 1 ) non - randomly located biodegradable barrier material , ( 2 ) non - biodegradable material and ( 2 ) drug material . in addition , the matrix and coating have at least one opening for drug delivery . likewise , the matrix should have one or , preferably , more channels for drug delivery . further , it also is contemplated that the drug material may or may not be mixed with the barrier material . further design options are discussed below . fig3 illustrates some of the novel aspects of this application . circle 18 of this figure shows a representative close - up view of one section of the implant device 2 for the first embodiment . again , it should be understood that the size , shape , location and structure of the channel ( s ) in the matrix may be configured in many different ways to ensure the desired drug delivery mechanism . thus , the present invention is intended to provide great flexibility in drug delivery , especially when 3 - d printing processes are used to make some or all of the matrix layers . more specifically , the implant 2 ( partially shown ) in fig3 has an opening 10 ( partially shown ), an opening sidewall 16 ( partially shown ), an impervious coating 12 ( partially shown ) and a matrix 14 ( partially shown ). in that regard , matrix 14 contains several elements . for example , the matrix 14 in this embodiment includes a non - biodegradable matrix portion 19 having channels 20 containing at least two different materials . the different materials in the channels of this embodiment are drug material 22 and biodegradable barrier 24 . the biodegradable barrier material 24 for this embodiment ( and at least some other embodiments ) may be the same as or different from other biodegradable materials in the matrix . furthermore , it is expressly contemplated that the barriers may be made of different biodegradable materials and may be of different thicknesses or other dimensions . thus , for example , different biodegradable materials and thicknesses may be utilized to provide enhanced drug release timing options . as shown in fig3 , barriers 24 can be placed in various locations within the drug containing channels 20 . for example , one or more biodegradable barriers 24 can be created at or near opening sidewall 16 to moderate the initial drug burst phenomena . barriers 24 also may be placed in other locations in channel 20 to create mini - chambers for drug materials . as explained above , these biodegradable barriers are structures used to regulate the time and amount of drug release . it is expressly contemplated ( but not required ) that the barriers be staggered in the various channels so that the initial burst of a mini - chamber in one channel is somewhat or largely cancelled out by the drug delivery from the mini - chambers of other channels . this staggering approach may be used from the beginning to the end of the drug delivery . in addition , in a preferred embodiment , the non - randomly located biodegradable barriers may be created at the end of every channel at the opening sidewall . this will avoid any premature release of drug material prior to implanting . likewise , the drug delivery may be regulated by the use of different thicknesses of the barriers . alternatively , or in addition , the barriers may be made of different biodegradable materials so that drug delivery may be regulated in that way as well . finally , another approach is regulate drug delivery is to incorporate some drug material into the barriers ( especially in barriers located at the opening sidewalls ). as previously discussed , drug material 22 may be one or more different types of drugs . thus , for example , one or more types of drug material may be used in a first group of mini - channels and other types of drug material may be used in later mini - chambers or in different channels . alternatively , the %&# 39 ; s of drug materials may be varied in particular mini - chambers / channels . the ability to flexibly employ various drugs and various drug levels in different mini - chambers / channels is believed to be enhanced by 3 - d printing processes . in a second embodiment , the matrix is surrounded by an impervious coating and the matrix is comprised of , inter alia , at least one ( 1 ) non - randomly located biodegradable barrier material , ( 2 ) coating material used as a non - biodegradable material and ( 3 ) drug material . in addition , the matrix and coating have at least one opening for drug delivery . once again , the drug material may or may not be mixed with the barrier material . further design options are discussed elsewhere in this application . fig4 illustrates some of the other novel aspects of this application . circle 18 of this figure shows a representative close - up view of one section of the implant device 2 for the second embodiment . more specifically , the implant 2 ( partially shown ) has an opening 110 ( partially shown ), an opening sidewall 116 ( partially shown ), an impervious coating 112 ( partially shown ) and a matrix 114 ( partially shown ). once again , matrix 114 contains several elements . for example , the matrix 114 in this embodiment includes a non - biodegradable matrix portion 112 ′ made from the same impervious materials as coating 112 . in addition , the non - biodegradable matrix material 112 ′ has channels 120 containing different materials . the different materials in this embodiment are drug material 122 and non - randomly located biodegradable barriers 124 . as shown in fig4 , barriers 124 can be placed in various locations within the drug containing channels 120 . for example , one or more biodegradable barriers 124 can be created at or near opening sidewall 116 to moderate the initial drug burst phenomena . barriers 124 also may be placed in other locations in channel 120 to create mini - chambers for drug materials . as previously discussed , drug material 122 may be one or more different types of drugs . in addition to the above concepts , the use of only biodegradable materials in the matrix may be beneficial in the delivery of the drug material because it may lessen the % of drug materials that are remain in the implant device when ( a ) the drug delivery is substantially completed and / or ( b ) the implant is removed . for example , the capillary action effect in terms of drug delivery may decrease as the distance from the opening ( s ) increase . this may inhibit the delivery of all drug materials in the implant to the patient . thus , in a third embodiment , the matrix surrounded by an impervious coating and the matrix is comprised of , inter alia , of ( 1 ) at least two different biodegradable materials and ( 2 ) at least one drug material . the two biodegradable materials typically have different rates of biodegradability so as to regulate / control drug delivery . in addition , the matrix and coating have at least one opening for drug delivery . as indicated previously , a drug material may or may not be mixed with the barrier material . further design options are discussed elsewhere in this application . for example , one option is for one or more drug materials to be mixed with a biodegradable material in a matrix barrier and / or in the biodegradable material of the matrix . in addition , another option is to form the barriers from different and / or multiple biodegradable materials . this is yet another way in which drug delivery may be regulated by non - randomly located biodegradable materials . fig5 illustrates some of the other novel aspects of this application . circle 18 of this figure shows a representative close - up view of one section of the implant device 2 for the third embodiment . more specifically , the implant 2 ( partially shown ) has an opening 210 ( partially shown ), an opening sidewall 216 ( partially shown ), an impervious coating 212 ( partially shown ) and a matrix 214 ( partially shown ). in that regard , matrix 214 contains several elements . for example , the matrix in this embodiment includes at least two different biodegradable materials 218 and 224 . the matrix also has channels 220 containing different materials . the different materials in this embodiment are drug material 222 and biodegradable barrier 224 . as shown in fig5 , non - randomly located barriers 224 may be placed in various locations within the drug containing channels 220 . for example , one or more biodegradable barriers 224 can be created at or near opening sidewall 216 to moderate the initial drug burst phenomena . barriers 224 also may be placed in other locations in channel 220 to create mini - chambers for drug materials . as previously discussed , drug material 222 may be one or more different types of drugs . in a fourth embodiment , the matrix does not have an impervious coating . instead , the coating also is biodegradable . in that situation , the matrix is comprised of , inter alia , of ( 1 ) at least two different biodegradable materials and ( 2 ) at least one drug material . the two biodegradable materials in the matrix have different rates of biodegradability so as to regulate / control drug delivery . furthermore , because the coating is biodegradable , the coating preferably should have a much lower / slower rate of biodegradability than the biodegradable materials in the matrix so that the drug delivery is maintained only through the one or more original openings in the coating . as indicated previously , the drug material may or may not be mixed with the barrier material . in addition , the matrix and coating have at least one opening for drug delivery . fig6 illustrates some of the other novel aspects of this application . circle 18 of this figure shows a representative close - up view of one section of the implant device 2 for the fourth embodiment . more specifically , the implant 2 ( partially shown ) has an opening 310 ( partially shown ), an opening sidewall 316 ( partially shown ), a biodegradable or semi - biodegradable coating 312 ( partially shown ) and a matrix 314 ( partially shown ). in that regard , matrix 214 contains several elements . for example , the matrix 314 in this embodiment includes a biodegradable matrix portion 318 that has channels 320 containing different materials . the different materials in this embodiment are drug material 322 and biodegradable barrier 324 . as shown in fig6 , barriers 324 can be placed in various locations within the drug containing channels 320 . for example , one or more biodegradable barriers 324 can be created at or near opening sidewall 316 to moderate the initial drug burst phenomena . barriers 324 also may be placed in other locations in channel 320 to create mini - chambers for drug materials . as previously discussed , drug material 322 may be one or more different types of drugs . in a fifth embodiment , the previous four embodiments are modified so as to also incorporate the use of anticoagulant materials to avoid and / or limit blood clotting when the device is implanted . the anticoagulant materials may be applied to various parts of the implant . for example , the anticoagulant material may be , inter alia , ( i ) applied to various areas of the coating such as on top of the coating or as a part of the exterior of the coating , ( ii ) applied to one or more surfaces of the opening ( s ) and / or ( iii ) mixed with the matrix materials . the fifth embodiment is illustrated in fig7 . there , anticoagulant material is applied topically to various locations ( such as locations 428 ) on coating 412 . alternatively , anticoagulant material can be topically applied to surfaces ( such as opening sidewall surface 416 ) of opening 410 . and / or , the anticoagulant material may be mixed with drug material 422 , matrix material 418 and / or barriers 324 within matrix 414 . in a sixth embodiment ( not shown in a figure ), anticoagulant material may be incorporated within a portion of the coating . in one approach , the anticoagulant material may incorporated into or on top of the coating by 3 - d printing methods ( via , for example , very small channels opening on the surface of the coating ) or by non - 3 - d printing methods ( via , for example , a separate biodegradeable material located on the outside surface of the coating ). in a seventh embodiment ( also not shown in a figure ), the matrix is formed as a mixture of materials — i . e ., without defined channels . although a 3 - d printing process may be used , this matrix structure also may be obtained by a non - 3 - d printing process . in that seventh embodiment situation , it is envisioned that the materials ( e . g ., the composition and % mixtures ) will vary throughout the matrix in order to reduce the “ initial burst ,” to maintain a more level of drug delivery ( or , alternatively , to adjust the rate of drug so that at certain desired times drug material is delivered in a higher or lower %) and / or to provide anticoagulant material . thus , this is another way in which the use of different matrix material compositions may be formed ( e . g ., by extrusion , partial material removal and subsequent liquid deposition ) so as to create so - called non - randomly located biodegradable materials / barriers having different compositions which are intended to regulate the delivery of drug materials . a coating material ( s ) may be subsequently applied to the matrix ( via , e . g ., shrink wrap ) and , thereafter , one or more openings may be created in the implant . in another approach , the type of biodegradable material may vary with , in one approach , a slower dissolving rate biodegradable material being close to the opening and with different biodegradable material having faster dissolving rates farther from the opening . thus , an initial level of drug delivery may be established and then a higher rate of drug delivery is established during a subsequent drug delivery period ( s ). in addition to or as an alternative , a lower % of drug material may be located closer to the implant opening to avoid / lessen the initial drug burst . thus , the present invention contemplates that the % of the drug material may be varied ( e . g ., increased and / or decreased ) as the distance increases from the opening . moreover , in addition to or as yet another alternative , the anticoagulant material may be located in the matrix mixture just in the area nearer to the opening or that material may be included , for example , in lower , higher or the same dosages elsewhere in the biodegradable matrix . in that regard , it may be desirable to have anticoagulant material delivered at a time relatively close to the removal of the implant . furthermore , the invention is intended to provide an improved implant where the matrix barrier materials and drug materials are varied — in terms of locations materials and %. the exact choice of biodegradable materials and the % concentration at different locations may be adjusted depending , for example , upon the drug material ( s ) to be delivered to the patient . as indicated above , the present invention covers the situation where the 3 - d printing method is used to create all or just a portion of the implant device — e . g ., at least only 3 or more layers of the matrix . however , the invention also contemplates the situation where one or more layers of the matrix and / or coating are created by other methods . further , the present invention also envisions processes that deposit layers having the same or different thicknesses . the seventh embodiment also may be used with distinct walls and / or distinct channels as shown in other embodiments . in other words , modifications and / or variations may be readily made to all embodiments without departing from the spirit or scope of my inventions . finally , in the situation where more than one drug material is desired , this invention also envisions the use of one or more openings to deliver these different drugs either separately , serially or together in terms of times and locations . some of the potential advantages resulting from the use of the above non - randomly located biodegradable barriers and / or anticoagulant materials include at least the following : 1 . the use of non - randomly located biodegradable barrier structures may permit a higher % of drug materials in the implant to be delivered to the patient ; and 2 . the use of non - randomly located biodegradable barrier structures may permit a more “ flat ” or “ steady ” level of drug delivery ; and 3 . blood clotting may be reduced by incorporating anticoagulant material in or on the implant ; and 4 . removal of the implant may be easier if anticoagulant materials are used ; and 5 . the timing and level of drug delivery may be adjusted by the use of the biodegradable barrier structures and / or other biodegradable matrix materials having different compositions and dimensions ; and 6 . the use of non - randomly located biodegradable barrier structures may enhance the timed delivery of two or more drugs . these embodiments and potential advantages are intended to merely be examples . as may be readily appreciated by those of ordinary skill in the manufacture and design of medical implant art , the present inventions can be practiced in ways other than as specifically disclosed herein . thus , while the inventions have been described generally and with respect to certain preferred embodiments , it is to be understood that the foregoing and other modifications and variations may be made without departing from the scope or spirit of my inventions .