# US 6,741,877 B1 · Device and method for determining analyte levels > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,741,877 B1 - Document ID: US6741877B1 - Status: Granted - Kind: B1 - Application number: 09/489,588 - Filed: 2000-01-21 - Granted: 2004-05-25 - Earliest claimed: 1997-03-04 - Assignees: DexCom, Inc. - Inventors: Mark C. Shults; Stuart J. Updike; Rathbun K. Rhodes - Web page: https://patentgrep.com/patent/US6741877B1 ## CPC - A61B 5/14865: {invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors} - A61B 5/14532: {for measuring glucose, e.g. by tissue impedance measurement} - C12Q 1/006: {for glucose} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - C12Q: MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS (immunoassay G01N33/53); COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES ## Abstract Devices and methods for determining analyte levels are described. The devices and methods allow for the implantation of analyte-monitoring devices, such as glucose monitoring devices, that result in the delivery of a dependable flow of blood to deliver sample to the implanted device. The devices comprise a unique microarchitectural arrangement in the sensor region that allows accurate data to be obtained over long periods of time. ## Claims ### Claim 1 A device for measuring glucose in a biological fluid, comprising: a) a housing comprising an electronic circuit and at least two electrodes operatively connected to said electronic circuit; and b) a sensor operably connected to said electrodes of said housing, said sensor comprising an apparatus for determining the amount of glucose in a biological sample, said glucose determining apparatus operably associated with said electrodes and comprising a membrane impregnated with an oxidase, a bioprotective membrane substantially impermeable to macrophages, said bioprotective membrane positioned more distal to said housing than said oxidase impregnated membrane, and an angiogenic layer, said angiogenic layer positioned more distal to said housing than said bioprotective membrane, wherein said sensor protrudes from said housing. ### Claim 2 (depends on 1) The biological fluid measuring device of claim 1, wherein the sensor further comprises a sensor interface dome. ### Claim 3 (depends on 1) The biological fluid measuring device of claim 1, wherein said membrane impregnated with oxidase comprises a resistance layer, an enzyme layer, an interference layer and an electrolyte layer. ### Claim 4 (depends on 3) The biological fluid measuring device of claim 3, wherein said resistance layer comprises a polymer membrane with a oxygen-to-glucose permeability ratio of approximately 200:1. ### Claim 5 (depends on 3) The biological fluid measuring device of claim 3, wherein said interference layer comprises a hydrophobic membrane substantially permeable to hydrogen peroxide. ### Claim 6 (depends on 3) The biological fluid measuring device of claim 3, wherein said interference layer comprises a hydrophobic membrane substantially impermeable to chemical compositions having a molecular weight substantially greater than hydrogen peroxide. ### Claim 7 (depends on 3) The biological fluid measuring device of claim 3, wherein said electrolyte layer comprises a semipermeable hydrophilic coating. ### Claim 8 (depends on 7) The biological fluid measuring device of claim 7, wherein said electrolyte layer comprises a curable copolymer of a urethane polymer and a hydrophilic film-forming polymer. ### Claim 9 (depends on 1) The biological fluid measuring device of claim 1, wherein said bioprotective membrane comprises polypropylene, polysulphone, polytetrafluoroethylene, or poly(ethylene terephthalate). ### Claim 10 (depends on 1) The biological fluid measuring device of claim 1, wherein said bioprotective membrane further comprises pores having a diameter of about 0.4 μm. ### Claim 11 (depends on 1) The biological fluid measuring device of claim 1, wherein said angiogenic layer is selected from the group consisting of hydrophilic polyvinylidene fluoride, mixed cellulose esters, polyvinyl chloride, polypropylene, polysulphone and polymethacrylate. ### Claim 12 (depends on 1) The biological fluid measuring device of claim 1, further comprising c) a securing element for securing said device to biological tissue, said securing element composed of a material selected from the group consisting of polyester, polypropylene cloth, polytetrafluoroethylene felts and expanded polytetrafluoroethylene. ### Claim 13 (depends on 12) The biological fluid measuring device of claim 12, wherein said securing element comprises a polyester velour. ### Claim 14 (depends on 1) The biological fluid measuring device of claim 1, wherein said housing comprising said electronic circuit is filled with material comprising waxes and resins wherein said waxes and resins secure said electronic circuit within said housing. ### Claim 15 (depends on 1) The device of claim 1, wherein said sensor comprises an interface tip for communicating with the tissue of said host, said tip comprising a fixation domain adapted for substantial fixation of said tip in a foreign body capsule. ### Claim 16 (depends on 15) The device of claim 15, wherein said wherein said sensor tip fixation domain further comprises a capsular attachment layer. ### Claim 17 (depends on 16) The device of claim 16, wherein said capsular attachment layer comprises a porous implantable material. ### Claim 18 (depends on 16) The device of claim 16, wherein said capsular attachment layer comprises one of polyester, velour, expanded polytetrafluoroethylene, polytetrafluoroethylene felts, and polypropylene cloth. ### Claim 19 (depends on 16) The device of claim 16, wherein said capsular attachment layer comprises surgical grade polyester velour. ### Claim 20 (depends on 1) The device of claim 1, wherein said bioprotective membrane comprises polytetrafluoroethylene. ### Claim 21 (depends on 1) The device of claim 1, wherein said angiogenic membrane comprises polytetrafluoroethylene. ### Claim 22 (depends on 1) The device of claim 1, wherein said bioprotective membrane and said angiogenic layer are formed from a polytetrafluoroethylene. ### Claim 23 (depends on 1) The device of claim 1, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.1 micron to about 1.0 micron. ### Claim 24 (depends on 1) The device of claim 1, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.2 micron to about 0.5 micron. ### Claim 25 (depends on 1) The device of claim 1, wherein said electronic circuit operably connected to at least one of said electrodes is adapted for continuous, long-term operation. ### Claim 26 (depends on 1) The device of claim 1, wherein said housing further comprises an apparatus operatively connected to said electronic circuit for transmitting data to a location external to said device. ### Claim 27 (depends on 26) The device of claim 26, wherein said data transmitting apparatus comprises radiotelemetry. ### Claim 28 (depends on 1) The device of claim 1, wherein said device is wholly implantable. ### Claim 29 (depends on 28) The device of claim 28, wherein said device is sized and configured for being wholly implantable subcutaneously. ### Claim 30 (depends on 1) The device of claim 1, wherein said housing is substantially oval-shaped. ### Claim 31 A wholly implantable glucose monitoring device, comprising: a) a housing of size and configuration for whole implantation into a host; and b) a sensor supported by said housing for communication with tissue of said host, said sensor comprising (i) a member for determining the amount of glucose in biological fluid of said host, and (ii) a bioprotective member disposed more distal to said housing than said glucose determining member and comprising a bioprotective membrane that is substantially impermeable to macrophages and permeable to glucose and oxygen; and c) a member for securing the device to biological tissue of said host, said securing member cooperatively associated with said housing, and wherein said securing member comprises poly(ethylene terephthalate). ### Claim 32 (depends on 31) An implantable glucose monitoring device of claim 31, wherein said bioprotective membrane comprises pores, said pores having diameters ranging from about 0.1 micron to about 1.0 micron. ### Claim 33 (depends on 31) An implantable glucose monitoring device of claim 31, wherein said bioprotective membrane comprises polytetrafluoroethylene. ### Claim 34 (depends on 31) An implantable glucose monitoring device of claim 31, wherein said glucose determining member comprises a membrane containing glucose oxidase, said glucose oxidase-containing membrane positioned more proximal to said housing than said bioprotective member. ### Claim 35 (depends on 34) The device of claim 34, wherein said oxidase impregnated membrane comprises a single homogeneous structure. ### Claim 36 (depends on 35) The device of claim 35, wherein said glucose oxidase impregnated membrane comprises a resistance layer, and enzyme layer, an interference layer and an electrolyte layer. ### Claim 37 (depends on 36) The device of claim 36, wherein said resistance layer restricts the transport of glucose therethrough. ### Claim 38 (depends on 37) The device of claim 37, wherein said resistance layer comprises a polymer membrane with a oxygen-to-glucose permeability ratio of approximately 200:1. ### Claim 39 (depends on 36) The device of claim 36, wherein said interference layer comprises a hydrophobic membrane substantially permeable to hydrogen peroxide. ### Claim 40 (depends on 39) The device of claim 39, wherein said interference layer comprises a hydrophobic membrane substantially impermeable to chemical compositions having a molecular weight substantially greater than hydrogen peroxide. ### Claim 41 (depends on 37) The device of claim 37, wherein said electrolyte layer comprises a semipermeable hydrophilic coating. ### Claim 42 (depends on 41) The device of claim 41, wherein said electrolyte layer comprises a curable copolymer of a urethane polymer and a hydrophilic film-forming polymer. ### Claim 43 (depends on 31) An implantable glucose monitoring device of claim 31, wherein said device further comprises at least two electrodes supported by said housing and operably connected to said sensor. ### Claim 44 (depends on 43) An implantable glucose monitoring device of claim 43, wherein said device further comprises electronic circuitry operably connected to at least one of said electrodes and adapted for long-term operation. ### Claim 45 (depends on 44) The device of claim 44, wherein said housing comprising said electronic circuitry is filled with material comprising waxes and resins wherein said waxes and resins secure said electronic circuit within said housing. ### Claim 46 (depends on 44) The device of claim 44, wherein said housing further comprises an apparatus operatively connected to said electronic circuitry for transmitting data to a location external to said device. ### Claim 47 (depends on 46) The device of claim 46, wherein said data transmitting apparatus comprises radiotelemetry. ### Claim 48 (depends on 48) An implantable glucose monitoring device of claim 48, said housing comprising a cavity contained therewithin. ### Claim 49 (depends on 48) An implantable glucose monitoring device of claim 48, wherein said sensor is within said housing cavity. ### Claim 50 (depends on 31) The device of claim 31, wherein said sensor comprises an interface tip for communicating with the tissue of said host, said tip comprising a fixation domain adapted for substantial fixation of said tip in a foreign body capsule. ### Claim 51 (depends on 50) The device of claim 50, wherein said wherein said fixation domain further comprises a capsular attachment layer. ### Claim 52 (depends on 51) The device of claim 51, wherein said capsular attachment layer comprises a porous implantable material. ### Claim 53 (depends on 51) The device of claim 51, wherein said capsular attachment layer comprises one of polyester, velour, expanded polytetrafluoroethylene, polytetrafluoroethylene felts, and polypropylene cloth. ### Claim 54 (depends on 51) The device of claim 51, wherein said capsular attachment layer comprises surgical grade polyester velour. ### Claim 55 (depends on 31) The device of claim 31, further comprising an angiogenic layer positioned more distal to said housing than said bioprotective membrane. ### Claim 56 (depends on 55) The device of claim 55, wherein said angiogenic layer comprises one of hydrophilic polyvinylidene fluoride, mixed cellulose esters, polyvinyl chloride, polypropylene, polysulphone and polymethacrylate. ### Claim 57 (depends on 55) The device of claim 55, wherein said angiogenic layer comprises polytetrafluoroethylene. ### Claim 58 (depends on 55) The device of claim 55, wherein said bioprotective and angiogenic layers are formed from a polytetrafluoroethylene. ### Claim 59 (depends on 31) The device of claim 31, wherein said bioprotective membrane comprises one of polypropylene, polysulphone, polytetrafluoro ethylene, and poly(ethylene terephthalate). ### Claim 60 (depends on 31) The device of claim 31, wherein said device is sized and configured for being wholly implantable subcutaneously. ### Claim 61 (depends on 31) The device of claim 31, wherein said housing is substantially oval-shaped. ### Claim 62 (depends on 31) The device of claim 31, wherein said sensor further comprises a sensor interface dome that protrudes from said housing. ### Claim 63 A biological fluid measuring device, comprising: (a) a housing comprising an electronic circuit and at least two electrodes operably connected to said electronic circuit; and (b) a sensor operably connected to said electrodes of said housing, said sensor comprising (i) a bioprotective membrane, and (ii) an angiogenic layer said angiogenic layer positioned more distal to said housing than said bioprotective membrane, wherein said angiogenic layer comprises polytetrafluoroethylene. ### Claim 64 (depends on 63) The biological fluid measuring device of claim 63, wherein said bioprotective membrane is substantially impermeable to macrophages. ### Claim 65 (depends on 63) The biological fluid measuring devise of claim 63, wherein said bioprotective membrane comprises pores, said pores having diameters ranging from about 0.1 micron to about 1.0 micron. ### Claim 66 (depends on 63) The biological fluid measuring device of claim 63, wherein said bioprotective membrane comprises polytetrafluoroethylene. ### Claim 67 (depends on 63) The biological fluid measuring device of claim 63, further comprising (c) a member for securing said device to biological tissue, and securing member associated with said housing. ### Claim 68 (depends on 67) The biological fluid measuring device of claim 67, wherein said securing member comprises poly(ethylene terephthalate). ### Claim 69 (depends on 63) The biological fluid measuring device of claim 63, wherein said sensor further comprises a member for determining the amount of glucose in a biological sample. ### Claim 70 (depends on 69) The biological fluid measuring device of claim 69, wherein said glucose determining member comprises a membrane containing glucose oxidase, said glucose oxidase-containing membrane positioned more proximal to said housing than said bioprotective membrane. ### Claim 71 (depends on 70) The device of claim 70, wherein said glucose oxidase-containing membrane comprises a resistance layer, and enzyme layer, an interference layer and an electrolyte layer. ### Claim 72 (depends on 71) The device of claim 71, wherein said resistance layer restricts the transport of glucose therethrough. ### Claim 73 (depends on 71) The device of claim 71, wherein said resistance layer comprises a polymer membrane with a oxygen-to-glucose permeability ratio of approximately 200:1. ### Claim 74 (depends on 71) The device of claim 71, wherein said interference layer comprises a hydrophobic membrane substantially permeable to hydrogen peroxide. ### Claim 75 (depends on 74) The device of claim 74, wherein said interference layer comprises a hydrophobic membrane substantially impermeable to chemical compositions having a molecular weight substantially greater than hydrogen peroxide. ### Claim 76 (depends on 74) The device of claim 74, wherein said electrolyte layer comprises a semipermeable hydrophilic coating. ### Claim 77 (depends on 76) The device of claim 76, wherein said electrolyte layer comprises a curable copolymer of a urethane polymer and a hydrophilic film-forming polymer. ### Claim 78 (depends on 70) The device of claim 70, wherein said glucose oxidase-containing membrane comprises a single homogeneous structure. ### Claim 79 (depends on 67) The device of claim 67, wherein said securing member comprises one of polyester, polypropylene cloth, polytetrafluoroethylene felts and expanded polytetrafluoroethylene. ### Claim 80 (depends on 67) The device of claim 67, wherein said securing member comprises a polyester velour. ### Claim 81 (depends on 63) The device of claim 63, wherein said housing comprising said electronic circuit is filled with material comprising waxes and resins wherein said waxes and resins secure said electronic circuit within said housing. ### Claim 82 (depends on 81) The device of claim 81, wherein said data transmitting apparatus comprises radiotelemetry. ### Claim 83 (depends on 63) The device of claim 63, wherein said sensor further comprises an interface tip for communicating with the tissue of said host, said tip comprising a fixation domain adapted for substantial fixation of said tip in a foreign body capsule. ### Claim 84 (depends on 83) The device of claim 83, wherein said wherein said sensor tip fixation domain further comprises a capsular attachment layer. ### Claim 85 (depends on 84) The device of claim 84, wherein said capsular attachment layer comprises a porous implantable material. ### Claim 86 (depends on 84) The device of claim 84, wherein said capsular attachment layer comprises one of polyester, velour, expanded polytetrafluoroethylene, polytetrafluoroethylene felts, and polypropylene cloth. ### Claim 87 (depends on 84) The device of claim 84, wherein said capsular attachment layer comprises surgical grade polyester velour. ### Claim 88 (depends on 63) The device of claim 63, wherein said bioprotective membrane comprises one of polypropylene, polysulphone, polytetrafluoroethylene, and poly(ethylene terephthalate). ### Claim 89 (depends on 63) The device of claim 63, wherein said electronic circuit operably connected to said at least two electrodes is adapted for long-term operation. ### Claim 90 (depends on 63) The device of claim 63, wherein said device is wholly implantable. ### Claim 91 (depends on 90) The device of claim 90, wherein said device is sized and configured for being wholly implantable subcutaneously. ### Claim 92 (depends on 63) The device of claim 63, wherein said housing is substantially oval-shaped. ### Claim 93 (depends on 63) The device of claim 63, wherein said sensor further comprises a sensor interface dome that protrudes from said housing. ### Claim 94 A device for measuring glucose in a tissue of a host comprising: a wholly implantable device comprising a sensor having an interface tip for communicating with the tissue of said host, said tip comprising a fixation domain adapted for substantial fixation of said tip in a foreign bode capsule, wherein said sensor tip fixation domain comprises a capsular attachment layer on said sensor, and wherein said sensor tip fixation domain further comprises an angiogenic layer on said sensor. ### Claim 95 (depends on 94) The device of claim 94, wherein said wholly implantable device is sized and configured for being wholly implanted subcutaneously. ### Claim 96 (depends on 94) The device of claim 94, wherein said capsular attachment layer comprises surgical grade polyester velour. ### Claim 97 (depends on 94) The device of claim 94, further comprising a securing element for securing said device to biological tissue. ### Claim 98 (depends on 97) The device of claim 97, wherein said securing element comprises one of polyester, polypropylene cloth, polytetrafluoroethylene felts and expanded polytetrafluoroethylene. ### Claim 99 (depends on 98) The device of claim 98, wherein said securing element comprises a polyester velour. ### Claim 100 (depends on 94) The device of claim 94, wherein said capsular attachment layer comprises a porous implantable material. ### Claim 101 (depends on 94) The device of claim 94, wherein said capsular attachment layer comprises one of polyester, velour, expanded polytetrafluoroethylene, polytetrafluoroethylene felts, and polypropylene cloth. ### Claim 102 (depends on 94) The device of claim 94, wherein said angiogenic layer comprises one of hydrophilic polyvinylidene fluoride, mixed cellulose esters, polyvinyl chloride, polypropylene, polysulphone and polymethacrylate. ### Claim 103 (depends on 94) The device of claim 94, wherein said angiogenic layer comprises polytetrafluoroethylene. ### Claim 104 (depends on 94) The device of claim 94, further comprising a bioprotective membrane substantially impermeable to macrophages, said bioprotective membrane located proximal to said angiogenic layer. ### Claim 105 (depends on 106) The device of claim 106, wherein said bioprotective membrane comprises polytetrafluoroethylene. ### Claim 106 (depends on 104) The device of claim 104, wherein said bioprotective and angiogenic layers are formed from a polytetrafluoroethylene. ### Claim 107 (depends on 104) The device of claim 104, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.1 micron to about 1.0 micron. ### Claim 108 (depends on 104) The device of claim 104, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.2 micron to about 0.5 micron. ### Claim 109 (depends on 104) The device of claim 104, wherein said bioprotective membrane comprises one of polypropylene, polysulphone, polytetrafluoroethylene, and poly(ethylene terephthalate). ### Claim 110 (depends on 94) The device of claim 94, further comprising a membrane impregnated with an oxidase located proximal to said angiogenic layer. ### Claim 111 (depends on 110) The device of claim 110, wherein said oxidase impregnated membrane comprises a resistance layer, and enzyme layer an interference layer and an electrolyte layer. ### Claim 112 (depends on 111) The device of claim 111, wherein said resistance layer restricts the transport of glucose therethrough. ### Claim 113 (depends on 112) The device of claim 112, wherein said resistance layer comprises a polymer membrane with a oxygen-to-glucose permeability ratio of approximately 200:1. ### Claim 114 (depends on 111) The device of claim 111, wherein said interference layer comprises a hydrophobic membrane substantially permeable to hydrogen peroxide. ### Claim 115 (depends on 114) The device of claim 114, wherein said interference layer comprises a hydrophobic membrane substantially impermeable to chemical compositions having a molecular weight substantially greater than hydrogen peroxide. ### Claim 116 (depends on 111) The device of claim 111, wherein said electrolyte layer comprises a semipermeable hydrophilic coating. ### Claim 117 (depends on 116) The device of claim 116, wherein said electrolyte layer comprises a curable copolymer of a urethane polymer and a hydrophilic film-forming polymer. ### Claim 118 (depends on 111) The device of claim 111, wherein said enzyme layer contains glucose oxidase. ### Claim 119 (depends on 110) The device of claim 110, wherein said oxidase impregnated membrane comprises a single homogeneous structure. ### Claim 120 (depends on 94) The device of claim 94, further comprising a housing that has an electronic circuit and at least two electrodes operatively connected to said electronic circuit, wherein said sensor is operably connected to said electrodes of said housing. ### Claim 121 (depends on 120) The device of claim 120, wherein said housing comprising said electronic circuit is filled with material comprising waxes and resins wherein said waxes and secure said electronic circuit within said housing. ### Claim 122 (depends on 120) The device of claim 120, wherein said electronic circuit operably connected to at least one of said electrodes is adapted for long-term operation. ### Claim 123 (depends on 120) The device of claim 120, wherein said housing further comprises an apparatus operatively connected to said electronic circuit for transmitting data to a location external to said device. ### Claim 124 (depends on 123) The device of claim 123, wherein said data transmitting apparatus comprises radiotelemetry. ### Claim 125 (depends on 94) The device of claim 94, wherein said device is sized and configured for being wholly implantable subcutaneously. ### Claim 126 (depends on 94) The device of claim 94, wherein said housing is substantially oval-shaped. ### Claim 127 (depends on 94) The device of claim 94, wherein said sensor interface tip comprises a dome configuration. ### Claim 128 (depends on 127) The device of claim 127, wherein said sensor interface tip protrudes from said housing. ### Claim 129 An implantable device for subcutaneous monitoring of glucose levels, comprising a housing and a sensor comprising an angiogenic layer for promoting adequate microcirculatory delivery of glucose and oxygen to said sensor, wherein said sensor further comprises a capsular attachment layer. ### Claim 130 (depends on 129) The device of claim 129, wherein said implantable device is sized and configured for being wholly implanted subcutaneously. ### Claim 131 (depends on 129) The device of claim 129, further comprising a securing element for securing said device to biological tissue. ### Claim 132 (depends on 131) The device of claim 131, wherein said securing element comprises one of polyester, polypropylene cloth, polytetrafluoroethylene felts and expanded polytetrafluoroethylene. ### Claim 133 (depends on 132) The device of claim 132, wherein said securing element comprises a polyester velour. ### Claim 134 (depends on 129) The device of claim 129, wherein said angiogenic layer comprises one of hydrophilic polyvinylidene fluoride, mixed cellulose esters, polyvinyl chloride, polypropylene, polysulphone and polymethacrylate. ### Claim 135 (depends on 129) The device of claim 129, wherein said angiogenic layer comprises polytetrafluoroethylene. ### Claim 136 (depends on 129) The device of claim 129 further comprising a bioprotective membrane substantially impermeable to macrophages, said bioprotective membrane located proximal to said angiogenic layer. ### Claim 137 (depends on 136) The device of claim 136, wherein said bioprotective membrane comprises polytetrafluoroethylene. ### Claim 138 (depends on 136) The device of claim 136, wherein said bioprotective and angiogenic layers are formed from a polytetrafluoroethylene. ### Claim 139 (depends on 136) The device of claim 136, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.1 micron to about 1.0 micron. ### Claim 140 (depends on 136) The device of claim 136, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.2 micron to about 0.5 micron. ### Claim 141 (depends on 136) The device of claim 136, wherein said bioprotective membrane comprises one of polypropylene, polysulphone, polytetrafluoroethylene, and poly(ethylene terephthalate). ### Claim 142 (depends on 129) The device of claim 129, said sensor further comprising a membrane impregnated with an oxidase. ### Claim 143 (depends on 142) The device of claim 142, wherein said oxidase impregnated membrane comprises a resistance layer, and enzyme layer, an interference layer and an electrolyte layer. ### Claim 144 (depends on 142) The device of claim 142, wherein said oxidase impregnated membrane comprises a single homogeneous structure. ### Claim 145 (depends on 143) The device of claim 143, wherein said resistance layer restricts the transport of glucose therethrough. ### Claim 146 (depends on 145) The device of claim 145, wherein said resistance layer comprises a polymer membrane with a oxygen-to-glucose permeability ratio of approximately 200:1. ### Claim 147 (depends on 143) The device of claim 143, wherein said interference layer comprises a hydrophobic membrane substantially permeable to hydrogen peroxide. ### Claim 148 (depends on 143) The device of claim 143, wherein said interference layer comprises a hydrophobic membrane substantially impermeable to chemical compositions having a molecular weight substantially greater than hydrogen peroxide. ### Claim 149 (depends on 143) The device of claim 143, wherein said electrolyte layer comprises a semipermeable hydrophilic coating. ### Claim 150 (depends on 143) The device of claim 143, wherein said electrolyte layer comprises a curable copolymer of a urethane polymer and a hydrophilic film-forming polymer. ### Claim 151 (depends on 143) The device of claim 143, wherein said enzyme layer contains glucose oxidase. ### Claim 152 (depends on 129) The device of claim 129, wherein said housing comprises an electronic circuit and at least two electrodes operatively connected to said electronic circuit, and wherein said sensor is operably connected to said electrodes of said housing. ### Claim 153 (depends on 152) The device of claim 152, wherein said housing comprising said electric circuit is filled with material comprising waxes and resins wherein said waxes and resins secure said electronic circuit within said housing. ### Claim 154 (depends on 152) The device of claim 152, wherein said electronic circuit operably connected to at least one of said electrodes is adapted for long-term operation. ### Claim 155 (depends on 129) The device of claim 129, wherein said housing comprises an apparatus operatively connected to said electronic circuit for transmitting data to a location external to said device. ### Claim 156 (depends on 155) The device of claim 155, wherein said data transmitting apparatus comprises radiotelemetry. ### Claim 157 (depends on 129) The device of claim 129, wherein said device is sized and configured for being wholly implantable subcutaneously. ### Claim 158 (depends on 129) The device of claim 129, wherein said housing is substantially oval-shaped. ### Claim 159 (depends on 129) The device of claim 129, wherein said sensor comprises an interface tip that has a dome configuration. ### Claim 160 (depends on 159) The device of claim 159, wherein said interface tip protrudes from said housing. ### Claim 161 A device for measuring glucose in a biological fluid, comprising: a) a housing comprising an electronic circuit and at least two electrodes operatively connected to said electronic circuit; and b) a sensor operably connected to said electrodes of said housing, said sensor comprising an apparatus for determining the amount of glucose in a biological sample, said glucose determining apparatus operably associated with said electrodes and comprising a membrane impregnated with an oxidase, a bioprotective membrane substantially impermeable to macrophages, said bioprotective membrane positioned more distal to said housing than said oxidase impregnated membrane, and an angiogenic layer positioned more distal to said housing than said bioprotective membrane, wherein the sensor further comprises a sensor interface dome. ### Claim 162 (depends on 161) The device of claim 161, further comprising c) a securing element for securing said device to biological tissue. ### Claim 163 (depends on 162) The device of claim 162, wherein said securing element comprises one of polyester, polypropylene cloth, polytetrafluoroethylene felts and expanded polytetrafluoroethylene. ### Claim 164 (depends on 162) The device of claim 162, wherein said securing element comprises a polyester velour. ### Claim 165 (depends on 161) The device of claim 161, wherein said sensor interface dome comprises an interface tip for communicating with the tissue of said host, said tip comprising a fixation domain adapted for substantial fixation of said tip in a foreign body capsule. ### Claim 166 (depends on 165) The device of claim 165, wherein said wherein said fixation domain further comprises a capsular attachment layer. ### Claim 167 (depends on 166) The device of claim 166, wherein said capsular attachment layer comprises a porous implantable material. ### Claim 168 (depends on 166) The device of claim 166, wherein said capsular attachment layer comprises one of polyester, velour, expanded polytetrafluoroethylene, polytetrafluoroethylene felts, and polypropylene cloth. ### Claim 169 (depends on 166) The device of claim 166, wherein said capsular attachment layer comprises surgical grade polyester velour. ### Claim 170 (depends on 161) The device of claim 161, wherein said angiogenic layer comprises one of hydrophilic polyvinylidene fluoride, and mixed cellulose esters. ### Claim 171 (depends on 161) The device of claim 161, wherein said angiogenic layer comprises one of polyvinyl chloride, polypropylene, polysulphone, and polymethacrylate. ### Claim 172 (depends on 161) The device of claim 161, wherein said bioprotective membrane comprises polytetrafluoroethylene. ### Claim 173 (depends on 161) The device of claim 161, wherein said angiogenic layer comprises polytetrafluoroethylene. ### Claim 174 (depends on 161) The device of claim 161, wherein said bioprotective and angiogenic layers are formed from a polytetrafluoroethylene. ### Claim 175 (depends on 161) The device of claim 161, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.1 micron to about 1.0 micron. ### Claim 176 (depends on 161) The device of claim 161, wherein said bioprotective membrane comprises pores having diameter ranging forming about 0.2 micron to about 0.5 micron. ### Claim 177 (depends on 161) The device of claim 161, wherein said bioprotective membrane comprises one of polypropylene, polysulphone, polytetrafluoroethylene, and poly(ethylene terephthalate). ### Claim 178 (depends on 161) The device of claim 161, wherein said oxidase impregnated membrane comprises a single homogeneous structure. ### Claim 179 (depends on 161) The device of claim 161, wherein said oxidase impregnated membrane comprises a resistance layer, and enzyme layer, an interference layer and an electrolyte layer. ### Claim 180 (depends on 179) The device of claim 179, wherein said resistance layer restricts the transport of glucose therethrough. ### Claim 181 (depends on 179) The device of claim 179, wherein said resistance layer comprises a polymer membrane with a oxygen-to-glucose permeability ratio of approximately 200:1. ### Claim 182 (depends on 179) The device of claim 179, wherein said interference layer comprises a hydrophobic membrane substantially permeable to hydrogen peroxide. ### Claim 183 (depends on 179) The device of claim 179, wherein said interference layer comprises a hydrophobic membrane substantially impermeable to chemical compositions having a molecular weight substantially greater than hydrogen peroxide. ### Claim 184 (depends on 179) The device of claim 179, said electrolyte layer comprises a semipermeable hydrophilic coating. ### Claim 185 (depends on 184) The device of claim 184, wherein said electrolyte layer comprises a curable copolymer of a urethane polymer and a hydrophilic film-forming polymer. ### Claim 186 (depends on 179) The device of claim 179, wherein said enzyme layer contains glucose oxidase. ### Claim 187 (depends on 161) The device of claim 161, wherein said housing comprising said electronic circuit is filled with material comprising waxes and resins wherein said waxes and resins secure said electronic circuit within said housing. ### Claim 188 (depends on 161) The device of claim 161, wherein said electronic circuit operably connected to at least one of said electrodes is adapted for long-term operation. ### Claim 189 (depends on 161) The device of claim 161, wherein said housing further comprises an apparatus operatively connected to said electronic circuit for transmitting data to a location external to said device. ### Claim 190 (depends on 189) The device of claim 189, wherein said data transmitting apparatus comprises radiotelemetry. ### Claim 191 (depends on 161) The device of claim 161, wherein said device is wholly implantable. ### Claim 192 (depends on 191) The device of claim 191, wherein said device is sized and configured for being wholly implantable subcutaneously. ### Claim 193 (depends on 161) The device of claim 161, wherein said housing is substantially oval-shaped. ### Claim 194 (depends on 161) The device of claim 161, wherein said sensor interface dome protrudes from said housing. ### Claim 195 A device for measuring glucose in a biological fluid, comprising: a) a housing comprising an electronic circuit and at least two electrodes operatively connected to said electronic circuit; and b) a sensor operably connected to said electrodes of said housing, said sensor comprising an apparatus for determining the amount of glucose in a biological sample, said glucose determining apparatus operably associated with said electrodes and comprising a membrane impregnated with an oxidase, a bioprotective membrane substantially impermeable to macrophages, said bioprotective membrane positioned more distal to said housing than said oxidase impregnated membrane, and an angiogenic layer positioned more distal to said housing than said bioprotective membrane, wherein said membrane impregnated with oxidase comprises a resistance layer, and enzyme layer, an interference layer and an electrolyte layer. ### Claim 196 (depends on 195) The device of claim 195, further comprising c) a securing element for securing said device to biological tissue. ### Claim 197 (depends on 196) The device of claim 196, wherein said securing element comprises one of polyester, polypropylene cloth, polytetrafluoroethylene felts and expanded polytetrafluoroethylene. ### Claim 198 (depends on 196) The device of claim 196, wherein said securing element comprises a polyester velour. ### Claim 199 (depends on 196) The device of claim 196, wherein said sensor comprises an interface tip for communicating with the tissue of said host, said tip comprising a fixation domain adapted for substantial fixation of said tip in a foreign body capsule. ### Claim 200 (depends on 199) The device of claim 199, wherein said wherein said fixation domain further comprises a capsular attachment layer. ### Claim 201 (depends on 200) The device of claim 200, wherein said capsular attachment layer comprises a porous implantable material. ### Claim 202 (depends on 200) The device of claim 200, wherein said capsular attachment layer comprises one of polyester, velour, expanded polytetrafluoroethylene, polytetrafluoroethylene felts, and polypropylene cloth. ### Claim 203 (depends on 200) The device of claim 200, wherein said capsular attachment layer comprises surgical grade polyester velour. ### Claim 204 (depends on 195) The device of claim 195, wherein said angiogenic layer comprises one of hydrophilic polyvinylidene fluoride, mixed cellulose esters, polyvinyl chloride, polypropylene, polysulphone and polymethacrylate. ### Claim 205 (depends on 195) The device of claim 195, wherein said bioprotective membrane comprises polytetrafluoroethylene. ### Claim 206 (depends on 195) The device of claim 195, wherein said angiogenic layer comprises polytetrafluoroethylene. ### Claim 207 (depends on 195) The device of claim 195, wherein said bioprotective and angiogenic layers are formed from a polytetrafluoroethylene. ### Claim 208 (depends on 195) The device of claim 195, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.1 micron to about 1.0 micron. ### Claim 209 (depends on 208) The device of claim 208, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.2 micron to about 0.5 micron. ### Claim 210 (depends on 195) The device of claim 195, wherein said bioprotective membrane comprises one of polypropylene, polysulphone, polytetrafluoroethylene, and poly(ethylene terephthalate). ### Claim 211 (depends on 195) The device of claim 195, wherein said resistance layer restricts the transport of glucose therethrough. ### Claim 212 (depends on 211) The device of claim 211, wherein said resistance layer comprises a polymer membrane with a oxygen-to-glucose permeability ratio of approximately 200:1. ### Claim 213 (depends on 195) The device of claim 195, wherein said interference layer comprises a hydrophobic membrane substantially permeable to hydrogen peroxide. ### Claim 214 (depends on 213) The device of claim 213, wherein said interference layer comprises a hydrophobic membrane substantially impermeable to chemical compositions having a molecular weight substantially greater than hydrogen peroxide. ### Claim 215 (depends on 195) The device of claim 195, wherein said electrolyte layer comprises a semipermeable hydrophilic coating. ### Claim 216 (depends on 215) The device of claim 215, wherein said electrolyte layer comprises a curable copolymer of a urethane polymer and a hydrophilic film-forming polymer. ### Claim 217 (depends on 195) The device of claim 195, wherein said enzyme layer contains glucose oxidase. ### Claim 218 (depends on 195) The device of claim 195, wherein said housing comprising said electronic circuit is filled with material comprising waxes and resins wherein said waxes and resins secure said electric circuit within said housing. ### Claim 219 (depends on 195) The device of claim 195, wherein said electronic circuit operably connected to at least one of said electrodes is adapted for long-term operation. ### Claim 220 (depends on 195) The device of claim 195, wherein said housing further comprises an apparatus operatively connected to said electronic circuit for transmitting data to a location external to said device. ### Claim 221 (depends on 220) The device of claim 220, wherein said data transmitting apparatus comprises radiotelemetry. ### Claim 222 (depends on 195) The device of claim 195, wherein said device is wholly implantable. ### Claim 223 (depends on 222) The device of claim 222, said device is sized and configured for being wholly implantable subcutaneously. ### Claim 224 (depends on 195) The device of claim 195, wherein said housing is substantially oval-shaped. ### Claim 225 (depends on 195) The device of claim 195, wherein said sensor further comprises a sensor interface dome that protrudes from said housing. ### Claim 226 A device for measuring glucose in a biological fluid, comprising: a) a housing comprising an electronic circuit and at least two electrodes operatively connected to said electronic circuit; b) a sensor operably connected to said electrodes of said housing, said sensor comprising an apparatus for determining the amount of glucose in a biological sample, said glucose determining apparatus operably associated with said electrodes and comprising a membrane impregnated with an oxidase, a bioprotective membrane substantially impermeable to macrophages, said bioprotective membrane positioned more distal to said housing than said oxidase impregnated membrane, and an angiogenic layer positioned more distal to said housing than said bioprotective membrane, c) a securing element for securing said device to biological tissue, said securing element composed of a material selected from the group consisting of polyester, polypropylene cloth, polytetrafluoroethylene felts and expanded polytetrafluoroethylene. ### Claim 227 (depends on 226) The device of claim 226, wherein said securing element comprises a polyester velour. ### Claim 228 (depends on 226) The device of claim 226, wherein said sensor comprises an interface tip for communicating with the tissue of said host, said tip comprising a fixation domain adapted for substantial fixation of said tip in a foreign body capsule. ### Claim 229 (depends on 228) The device of claim 228, wherein said wherein said fixation domain further comprises a capsular attachment layer. ### Claim 230 (depends on 229) The device of claim 229, wherein said capsular attachment layer comprises a porous implantable material. ### Claim 231 (depends on 229) The device of claim 229, wherein said capsular attachment layer comprises one of polyester, velour, expanded polytetrafluoroethylene, polytetrafluoroethylene felts, and polypropylene cloth. ### Claim 232 (depends on 229) The device of claim 229, wherein said capsular attachment layer comprises surgical grade polyester velour. ### Claim 233 (depends on 226) The device of claim 226, wherein said angiogenic layer comprises one of hydrophilic polyvinylidene fluoride, mixed cellulose esters, polyvinyl chloride, polypropylene, polysulphone and polymethacrylate. ### Claim 234 (depends on 226) The device of claim 226, wherein said bioprotective membrane comprises polytetrafluoroethylene. ### Claim 235 (depends on 226) The device of claim 226, wherein said angiogenic layer comprises polytetrafluoroethylene. ### Claim 236 (depends on 226) The device of claim 226, wherein said bioprotective and angiogenic layers are formed from a polytetrafluoroethylene. ### Claim 237 (depends on 226) The device of claim 226, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.1 micron to about 1.0 micron. ### Claim 238 (depends on 226) The device of claim 226, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.2 micron to about 0.5 micron. ### Claim 239 (depends on 226) The device of claim 226, wherein said bioprotective membrane comprises one of polypropylene, polysulphone, polytetrafluoroethylene, and poly(ethylene terephthalate). ### Claim 240 (depends on 226) The device of claim 226, wherein said oxidase impregnated membrane comprises a resistance layer, and enzyme layer, an interference layer and an electrolyte layer. ### Claim 241 (depends on 226) The device of claim 226, wherein said oxidase impregnated membrane comprises a single homogeneous structure. ### Claim 242 (depends on 240) The device of claim 240, wherein said resistance layer restricts the transport of glucose therethrough. ### Claim 243 (depends on 240) The device of claim 240, wherein said resistance layer comprises a polymer membrane with a oxygen-to-glucose permeability ratio of approximately 200:1. ### Claim 244 (depends on 240) The device of claim 240, wherein said interference layer comprises a hydrophobic membrane substantially permeable to hydrogen peroxide. ### Claim 245 (depends on 240) The device of claim 240, wherein said interference layer comprises a hydrophobic membrane substantially impermeable to chemical compositions having a molecular weight substantially greater than hydrogen peroxide. ### Claim 246 (depends on 240) The device of claim 240, wherein said electrolyte layer comprises a semipermeable hydrophilic coating. ### Claim 247 (depends on 246) The device of claim 246, wherein said electrolyte layer comprises a curable copolymer of a urethane polymer and a hydrophilic film-forming polymer. ### Claim 248 (depends on 240) The device of claim 240, wherein said enzyme layer contains glucose oxidase. ### Claim 249 (depends on 226) The device of claim 226, wherein said housing comprising said electronic circuit is filled with material comprising waxes and resins wherein said waxes and resins secure said electronic circuit within said housing. ### Claim 250 (depends on 226) The device of claim 226, wherein said electronic circuit operably connected to at least one of said electrodes is adapted for long-term operation. ### Claim 251 (depends on 226) The device of claim 226, wherein said housing further comprises an apparatus operatively connected to said electronic circuit for transmitting data to a location external to said device. ### Claim 252 (depends on 251) The device of claim 251, wherein said data transmitting apparatus comprised radiotelemetry. ### Claim 253 (depends on 226) The device of claim 226, wherein said device is wholly implantable. ### Claim 254 (depends on 180) The device of claim 180, wherein said device is sized and configured for being wholly implantable subcutaneously. ### Claim 255 (depends on 229) The device of claim 229, wherein said housing is substantially oval-shaped. ### Claim 256 (depends on 226) The device of claim 226, wherein said sensor further comprises a sensor interface dome that protrudes from said housing. ### Claim 257 A biological fluid measuring device, comprising: a) a housing comprising an electronic circuit and at least two electrodes operably connected to said electronic circuit; and b) a sensor operably connected to said electrodes of said housing, said sensor comprising (i) a bioprotective membrane, and (ii) an angiogenic layer, said angiogenic layer positioned more distal to said housing than said bioprotective membrane; and c) a member for securing said device to biological tissue, and securing member associated with said housing. ### Claim 258 (depends on 257) The device of claim 257, wherein said securing element comprises one of a material selected from the group consisting of polyester, polypropylene cloth, polytetrafluoroethylene felts and expanded polytetrafluoroethylene. ### Claim 259 (depends on 258) The device of claim 258, wherein said securing element comprises a polyester velour. ### Claim 260 (depends on 257) The device of claim 257, wherein said sensor comprises an interface tip for communicating with the tissue of said host, said tip comprising a fixation domain adapted for substantial fixation of said tip in a foreign body capsule. ### Claim 261 (depends on 260) The device of claim 260, wherein said wherein said fixation domain further comprises a capsular attachment layer. ### Claim 262 (depends on 261) The device of claim 261, wherein said capsular attachment layer comprises a porous implantable material. ### Claim 263 (depends on 261) The device of claim 261, wherein said capsular attachment layer comprises one of polyester, velour, expanded polytetramethylene, polytetrafluoroethylene felts, and polypropylene cloth. ### Claim 264 (depends on 261) The device of claim 261, wherein said capsular attachment layer comprises surgical grade polyester velour. ### Claim 265 (depends on 257) The device of claim 257, wherein said angiogenic layer comprises one of hydrophilic polyvinylidene fluoride, mixed cellulose esters, polyvinyl chloride, polypropylene, polysulphone and polymethacrylate. ### Claim 266 (depends on 257) The device of claim 257, wherein said bioprotective membrane comprises polytetrafluoroethylene. ### Claim 267 (depends on 257) The device of claim 257, wherein said angiogenic layer comprises polytetrafluoroethylene. ### Claim 268 (depends on 257) The device of claim 257, wherein said bioprotective and angiogenic layers are formed from a polytetrafluoroethylene. ### Claim 269 (depends on 257) The device of claim 257, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.1 micron to about 1.0 micron. ### Claim 270 (depends on 257) The device of claim 257, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.2 micron to about 0.5 micron. ### Claim 271 (depends on 257) The device of claim 257, wherein said bioprotective membrane comprises one of polypropylene, polysulphone, polytetrafluoroethylene, and poly(ethylene terephthalate). ### Claim 272 (depends on 257) The device of claim 257, wherein said oxidase impregnated membrane comprises a resistance layer, and enzyme layer, an interference layer and an electrolyte layer. ### Claim 273 (depends on 272) The device of claim 272, wherein said oxidase impregnated membrane comprises a single homogeneous structure. ### Claim 274 (depends on 272) The device of claim 272, wherein said resistance layer restricts the transport of glucose therethrough. ### Claim 275 (depends on 274) The device of claim 274, wherein said resistance layer comprises a polymer membrane with a oxygen-to-glucose permeability ratio of approximately 200:1. ### Claim 276 (depends on 272) The device of claim 272, wherein said interference layer comprises a hydrophobic membrane substantially permeable to hydrogen peroxide. ### Claim 277 (depends on 276) The device of claim 276, wherein said interference layer comprises a hydrophobic membrane substantially impermeable to chemical compositions having a molecular weight substantially greater than hydrogen peroxide. ### Claim 278 (depends on 272) The device of claim 272, wherein said electrolyte layer comprises a semipermeable hydrophilic coating. ### Claim 279 (depends on 278) The device of claim 278, wherein said electrolyte layer comprises a curable copolymer of a urethane polymer and a hydrophilic film-forming polymer. ### Claim 280 (depends on 272) The device of claim 272, wherein said enzyme layer contains glucose oxidase. ### Claim 281 (depends on 257) The device of claim 257, wherein said housing comprising said electronic circuit is filled with material comprising waxes and resins wherein said waxes and resins secure said electronic circuit within said housing. ### Claim 282 (depends on 257) The device of claim 257, wherein said electronic circuit operably connected to at least one of said electrodes is adapted for long-term operation. ### Claim 283 (depends on 257) The device of claim 257, wherein said housing further comprises an apparatus operatively connected to said electronic circuit for transmitting data to a location external to said device. ### Claim 284 (depends on 283) The device of claim 283, wherein said data transmitting apparatus comprises radiotelemetry. ### Claim 285 (depends on 284) The device of claim 284, wherein said device is wholly implantable. ### Claim 286 (depends on 285) The device of claim 285, wherein said device is sized and configured for being wholly implantable subcutaneously. ### Claim 287 (depends on 257) The device of claim 257, wherein said housing is substantially oval-shaped. ### Claim 288 (depends on 257) The device of claim 257, wherein said sensor further comprises a sensor interface dome that protrudes from said housing. ### Claim 289 A device for measuring glucose in a tissue of a host comprising a wholly implantable device comprising a sensor comprising an interface tip for communicating with the tissue of said host, said tip comprising a fixation domain adapted for substantial fixation of said tip in a foreign body capsule, wherein said sensor tip fixation domain further comprises a capsular attachment layer made from surgical grade polyester velour on said sensor. ### Claim 290 (depends on 289) The device of claim 289, further comprising a securing element for securing said device to biological tissue. ### Claim 291 (depends on 290) The device of claim 290, wherein said securing element comprises one of polyester, polypropylene cloth, polytetrafluoroethylene felts and expanded polytetrafluoroethylene. ### Claim 292 (depends on 291) The device of claim 291, wherein said securing element comprises a polyester velour. ### Claim 293 (depends on 289) The device of claim 289, wherein said sensor tip fixation domain further comprises an angiogenic layer on said sensor. ### Claim 294 (depends on 293) The device of claim 293, wherein said angiogenic layer comprises one of hydrophilic polyvinylidene fluoride, mixed cellulose esters, polyvinyl chloride, polypropylene, polysulphone and polymethacrylate. ### Claim 295 (depends on 293) The device of claim 293, wherein said angiogenic layer comprises polytetrafluoroethylene. ### Claim 296 (depends on 289) The device of claim 289, further comprising a bioprotective membrane substantially impermeable to macrophages, said bioprotective membrane located proximal to said angiogenic layer. ### Claim 297 (depends on 296) The device of claim 296, wherein said bioprotective membrane comprises polytetrafluoroethylene. ### Claim 298 (depends on 296) The device of claim 296, wherein said bioprotective and angiogenic layers are formed from a polytetrafluoroethylene. ### Claim 299 (depends on 296) The device of claim 296, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.1 micron to about 1.0 micron. ### Claim 300 (depends on 296) The device of claim 296, wherein said bioprotective membrane comprises pores having diameter ranging from about 0.2 micron to about 0.5 micron. ### Claim 301 (depends on 296) The device of claim 296, wherein said bioprotective membrane comprises one of polypropylene, polysulphone, polytetrafluoroethylene, and poly(ethylene terephthalate). ### Claim 302 (depends on 301) The device of claim 301, said sensor further comprising a membrane impregnated with an oxidase. ### Claim 303 (depends on 302) The device of claim 302, wherein said oxidase impregnated membrane comprises a resistance layer, and enzyme layer, an interference layer and an electrolyte layer. ### Claim 304 (depends on 302) The device of claim 302, wherein said oxidase impregnated membrane comprises a single homogeneous structure. ### Claim 305 (depends on 303) The device of claim 303, wherein said resistance layer restricts the transport of glucose therethrough. ### Claim 306 (depends on 303) The device of claim 303, wherein said resistance layer comprises a polymer membrane with a oxygen-to-glucose permeability ratio of approximately 200:1. ### Claim 307 (depends on 303) The device of claim 303, wherein said interference layer comprises a hydrophobic membrane substantially permeable to hydrogen peroxide. ### Claim 308 (depends on 307) The device of claim 307, said interference layer comprises a hydrophobic membrane substantially impermeable to chemical compositions having a molecular weight substantially greater than hydrogen peroxide. ### Claim 309 (depends on 303) The device of claim 303, wherein said electrolyte layer comprises a semipermeable hydrophilic coating. ### Claim 310 (depends on 309) The device of claim 309, wherein said electrolyte layer comprises a curable copolymer of a urethane polymer and a hydrophilic film-forming polymer. ### Claim 311 (depends on 303) The device of claim 303, wherein said enzyme layer contains glucose oxidase. ### Claim 312 (depends on 289) The device of claim 289, comprising a housing that has an electronic circuit and at least two electrodes operatively connected to said electronic circuit, wherein said sensor is operably connected to said electrodes of said housing. ### Claim 313 (depends on 312) The device of claim 312, wherein said housing comprising said electronic circuit is filled with material comprising waxes and resins wherein said waxes and resins secure said electronic circuit within said housing. ### Claim 314 (depends on 312) The device of claim 312 wherein said electronic circuit operably connected to at least one of said electrodes is adapted for long-term operation. ### Claim 315 (depends on 312) The device of claim 312, wherein said housing further comprises an apparatus operatively connected to said electronic circuit for transmitting data to a location external to said device. ### Claim 316 (depends on 315) The device of claim 315, wherein said data transmitting apparatus comprises radiotelemetry. ### Claim 317 (depends on 289) The device of claim 289, wherein said device is sized and configured for being wholly implantable subcutaneously. ### Claim 318 (depends on 289) The device of claim 289, wherein said housing is substantially oval-shaped. ### Claim 319 (depends on 289) The device of claim 289, wherein said sensor interface tip comprises a dome configuration. ### Claim 320 (depends on 289) The device of claim 289, wherein said sensor interface tip protrudes from said housing.