Einige Inhalte dieser Anwendung sind momentan nicht verfügbar.
Wenn diese Situation weiterhin besteht, kontaktieren Sie uns bitte unterFeedback&Kontakt
1. (WO2018226245) DEVICES AND METHODS FOR ENHANCED SKIN PERFORATION FOR CONTINUOUS GLUCOSE MONITORING
Anmerkung: Text basiert auf automatischer optischer Zeichenerkennung (OCR). Verwenden Sie bitte aus rechtlichen Gründen die PDF-Version.


DE VICES AND METHODS FOR ENHANCED SKIN PERFORATION CONTINUOUS GLUCOSE MONITORING BACKGROUND OF THE INVENTION The invention relates to methods and apparatus for the concentration of an analyte or as for monitoring the glucose of a person having More the invention relates to sensors and tools and methods associated therewith for anaiyte levels or substantially In sonic the sensors and tools and methods analyte levels to confirm that there is an uninterrupted anaiyte flux where the concentration of the analyte may or may not vary daring the uninterrupted Diabetes is a disease for which there is no known cure at a syndrome characterized by hyperglycemia relative insulin Diabetes affects more than million people and is projected to affect more than 220 million people by the year There are almost 30 million children and adults in the United or of the who have Of these million have been diagnosed with the while unfortunately nearly remain it is estimated that one out of every three children today develop diabetes sometime during their Diabetes is usuall and can lead to a variety of severe health including coronary artery peripheral vascular blindness and The Center for Disease Control has reported that there is a strong association between being overweight high blood high asthma and with a body mass index of 40 or higher are than 7 times more likely to be diagnosed with There are two types of Type I diabetes diabetes and Type ΪΪ diabetes diabetes Varying degrees of insulin secretory failure may be present in both forms of In some diabetes is also characterized by insulin insulin is the ke hormone used in the storage and release of energy from As food is carbohydrates are converted to glucose and glucose is absorbed into the stream primarily the Excess glucose in the following stimulates insulin which promotes entry of glucose the which controls the rate of metabolism of secretion to control level of blood glucose both during and after a to keep the glucose ieveis at an optimum a person blood glucose levels are typically between 80 and 90 of blood during fasting aad between to during the first hour or so a meal For a person with the insulin response does not function properly due to inadequate levels of insulin production or insulin resulting in blood glucose levels below 80 during fasting and well above 140 after a persons suffering from diabetes have limited options for taking insulin orally or by In controlling weight and can impact the amount of insulin particularly for dependent Monitoring blood glucose levels is an process that is used to help diabetics maintain blood glucose level as near as normal as possible throughout the The blood glucose market is the largest market for diagnostic products in the a size of approximately over S3 billion the United States and It is estimated that the worldwide glucose will amount to billion by Failure to manage the disease properly has dire consequences for The and indirect annual costs of diabetes in the United States was than billion in There are two type of blood glucose monitoring systems used by also known as single discrete or and continuous Episodic systems of meters and tests strips and require blood samples to be drawn from fingertips or alternate such as forearms and legs Ultra by a Johnson Johnson These systems on lancing and manipulation of the fingers or alternate blood draw which can be extremely painful and particularly for Continuous monitoring sensors are generall implanted subcutaneously and measure glucose levels in the interstitial fluid at various periods throughout the providing dat that shows trends glucose measurements over a short period of These sensors are painful during insertion and usually require the assistance of a health care these sensors intended for use during only a short duration monitoring for a matter of day s to determine a blood sugar Subcutaneously implanted sensors frequently lead to infection and immune response Another major drawback of currently available continuous monitoring devices is that they require often calibrations glucose must be obtained from painful using traditional meters and test and is required to maintain accuracy but it be cumbersome and Data from various studies such as the Diabetes Control and trial show that frequent testing of blood glucose levels is to improve the quality of life for most diabetics avoid frequent testing because of the and pain of pricking their or alternate sites to obtain blood Thus there is a need to develop simple glucose monitoring systems that eliminate or minimize these barriers to frequent With some embodiments of the proposed present invention a or diabetic patient can obtain 20 or more glucose test results over a two or three day period thus allowing frequent measurements on a daily Wearable devices are transforming the way millions of people around the world achieve health and fitness Wearable sensing devices can have diagnostic and These devices are currently used for physiological and biochemical as well as Other on the clinical application of interest can also be incorporated to determine a o verall health There are several commercially available wearable devices that measure galvanic skin skin heart rate and Some are believed to be working on wearable devices that may include glucose other analyte these devices for general health and wellness are not yet commercially Personal lifestyle and wellness monitors currently on the market measure such parameters as and calculate from these measurements physiological parameters such as calories burned and quality of Absent these fitness tracking is the direct measurement of glucose a key physiological parameter for those people who are interested in monitoring their glucose levels or users with metabolic syndrome or A device which could provide glucose level along other physiological would be much more and beneficial to users who keen to modify their lifestyles to attain better Continuous glucose monitoring has been shown to be a useful tool in improving average biood glucose levels and reducing glycemic excursions in persons with diabetes While usage of continuous glucose monitors has increased over the their adoption by the wider diabetic population has especially in with Type 2 diabetes persons who are Over 86 people the over age 20 have with blood sugar levels that are higher than but are not high to be classified as The pain and inconvenience associated with the implantation and wearing of commercially available sensor CGM devices has been to be one of the factors cited which wider adoption That some patients do not tolerate the device is substantiated by the high rate in clinical trials Much work has been done on the development of minimally invasive glucose sensors on the premise a device that is less painful and less obtrusive to wear would be attractive to a greater fraction of the and general the of minimally invasive continuous glucose monitoring devices has been the subject of much work b several Currently available glucose technologies such a blood testing and invasive needle sensor based CGM devices or technologies not suitable or convenient for daily use by people who are interested in monitoring their glucose levels to make behavioral and lifestyle there is a clear and an unmet need to develop convenient health wellness monitoring devices that contain glucose monitoring technologies or solutions which are minimally invasi ve and can be incorporated into eas to use wearable The wearable monitoring de vice using a or CGM technology could be a valuable for persons who are interested in monitoring their overall health and including persons with metabolic syndrome and With advances in sensor technologies and the advent of convenient wearable devices for minimally invasive CGM technology be also coupled with multiple sensor enabled health and wellness monitoring These devices provide and useful integrated actionable data structured to facilitate behavioral and lifestyle changes for improving glucose levels and overall health and the wearable device platform will enable helps people become more exercise sleep eat and manage their weight through the use of mobile data motivational and social Most commercially available wearable devices automatically track dail calories distance floors and display feedback to encourage them to become more active in their A wearable device capable of measuring and tracking giucose levels will enable users to understand consequences of their food on their glucose levels allow them thus to make desired lifestyle changes not only improve their Fitness state but their glucose Users of our wearable device would range potentially people interested in improving their health and fitness through everyday activities to individuals who may be BRIEF SUMMARY OF THE INVENTION The efficacy of tissue piercing elements i area of transdermal drug delivery is Multiple studies have that enhancement of skin via creation of microscopic pores the stratum can greatly improve the delivery rates of skin perforation with tissue piercing elements is not the only factor affecting the rate Other factors including such as the formulation of the drug and rate of closure of the micropores closure a lso need to Similarly micro tissue piercing elements have been used with less success by several workers for continuous glucose One of the invention is a method of in vi vo monitoring of an interstitial fluid glucose concentration comprising inserting a pluralit of tissue piercing elements with a simple applicator through a stratum layer of area of the indi tissue piercing elements immediately removed and a flexible giucose sensor gel patch impregnated one or more a chelating agents is applied to the perforated area on the To minimize the closure of the micropores within the perforated biochemical inhibitors can be incorporated in the reagent gel These biochemical inhibitors prevent skin healing b the synthesis of essential Keeping the micropores open allows consistent glucose thus minimizing the need for Another aspect of the invention is a method of in vivo monitoring of interstitial fluid glucose concentration comprising inserting a piuraiity of tissue piercing elements through a stratum layer of an area of the The tissue piercing elements each comprise a distal end in fluid communication with interstitial of the and a proximal in fluid communication with a sensing zone located outside of the body An interior space extends between the distal and proximal ends of the tissue piercing A sensing fluid fills substantially the entire interior space fluid concentration comprises a concentration of agents in a buffer One aspect of t he invention is a method of in vivo monitoring of an interstitial fluid glucose concentration comprising inserting a plurality of tissue piercing elements with a simple applicator through a stratum comeum layer of an area of the The tissue piercing elements are immediately removed and a flexible glucose sensor gel patch impregnated one or more a chelating applied to the perforated area on the One aspect of the is a of vivo monitoring of an interstitial fluid glucose concentration inserting a plurality of tissue piercing elements through a stratum layer of an area of the The tissue piercing elements each comprise a distal end fluid communication with interstitial fluid of the and a proximal end in fluid communication with a sensing zone located outside of the An interior space extends between the distal and proximal ends of the tissue piercing A sensing fluid fills substantially the entire interior space the sensing fluid concentration comprises a concentration of citrate in a buffer The concentration of citrate may range from raM to 200 preferably 1 5 Addition of citrate to a buffer solution in sensing fluid of a glucose monitoring device has shown to provide at least the following transdermal glucose flux is increased through the tissue piercing elements immediately after application of the tissue piercing elements to the a decrease in inhibition of transdermal glucose flux several hours after application a decrease in inhibition of transdermal glucose flux up to several days after application also One aspect of the invention is a method of in vivo monitoring of an interstitial fluid analyte The method comprises inserting a plurality of tissue piercing elements through a stratum layer of an area of the skin to create a plurality of said fluid paths each comprising a distal end in fluid communication with interstitial fluid of the individual a proximal end in fluid communication with a sensing zone located outside of the an interior space extending between the distal and proximal ends of t he fluid pat and a sensing fluid filling substantially the entire interior The method also comprises allowing at least one analyte to passively diffuse the interstitial fluid through the tissue piercing elements and the sensing The method further comprises sensing a concentration of the at least analyte m a the sensing zone using a sensor located at ieast partially in the sensing the sensing fluid comprises a concentration of an agent adapted to immediately increase an flux through the tissue piercing elements and to mitigate a decrease over time of the analyte flux through the tissue piercing the the sensing fluid concentration may comprise a sufficient concentration of citrate or other agent to mitigate a decrease of the analyte through tissue piercing elements for several The concentration of citrate may range from to 200 The citrate or other agent concentration be such at least of the interior spaces remain unblocked after 24 the citrate or other agent concentration may such that at least of the interior spaces remain unblocked after 48 in the the sensing fluid comprise a phosphate buffered saline The analyte ma Another aspect of the invention an analyte The analyte monitor comprises a plurality of fluid paths by a plurality of tissue piercing each fluid path comprising a distal opening adapted to be disposed on one side of a stratum l ayer of a a proximal opening adapted to be disposed another side of the stratum and interior space extending between the distal and proximal The analy te monitor comprises a sensing zone in fluid communication w ith the proximal openings of the fl uid the analyte monitor comprises a sensing fluid extending from the sensing zone into substantially entire interior space of the fluid wherein the sensing fluid comprises an agent adapted to increase an analyte flax through the fluid paths and to mitigate a decrease over time of the analyte flux through the fluid The analyte sensor is adapted to detect a concentration of analyte in the sensing fluid within sensing With regard to the analyte the concentration of citrate may range from 0 raM to 200 The sensing fluid may comprise a phosphate buffered saline solution and the analyte may be Another aspect of the invention is to incorporate the flexible glucose sensor gel pad after removal of the tissue piercing elements into a convenient wearable wellness monitor to enable glucose monitoring for 24 to 72hrs as shown in Figure Another aspect of the the wearable device technology platform as conceptualized below will be used to enhance the health wellness experience by enabling types of persons to make desired lifestyle changes not to improve their fitness state but also manage their glucose Our users would range potentially from people interested in improving their health and fitness through everyday activities to individuals who may be Yet another aspect of the invention is a method of in vivo monitoring of an interstitial fluid glucose concentration comprising insertin a plurality of tissue piercing elements a applicator a s layer of an area of the The element can be solid or planar there is a protrusion on the planar the protrusion penetrates tissue and an interstitial fluid glucose concentration is monitored through the planar Specifically for application with the use of the wearable wellness monitor the tissue piercing elements will be planar elongated tips about 200 microns length fabricated out of or elongated tips fabricated out of plastic BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS The novel features of the invention are set forth with particularity in the claims A better understanding of the features and advantages of the present invention will be obtained by reference to following detailed description that sets forth illustrative in which the principles of the in vention are and the accompanying drawings of is a perspective view of embodiment of the analyte monitor of this 2 is a view of the analyte monitor shown in 1 showing tissue piercing elements piercing through the 3 and 4 illustrate embodiments in which the analyte monitor comprises a plurality of calibration fluid reservoirs and a sensing fluid 5 shows an exploded view an monitor according to one embodiment of the i nven 6A and are schematic representative drawing of a three electrode system for use with the analyte sensor of one embodiment of this 6A shows electrodes a 6B shows the electrodes an a portion of substrate covered with a 7A are a schematic representative drawing of two electrode system for use with analyte of one embodiment of 7A shows electrodes on a and 7B shows the electrodes and a portion of the substrate covered with a 8 illustrates an a verage ratio of t reference blood glucose measurement for sensing blood 03 9 illustrates in ratio of transdermal glucose flux to reference blood glucose per hour for sensing blood glucose 10 illustrates percentage of initial transdermal glucose after 24 hours of glucose monitoring device illustrates percentage of initial glucose after 72 hours of glucose monitoring device illustrates the proximal ends of tissue piercing many of which are after use with a control i illustrates the proximal ends of tissue piercing elements after use with a buffer solution comprising illustrates percentage of unblocked tissue piercing element area within 24 and hours when citrate concentration is added to a sensing illustrates percentage of open tissue piercing element within 72 hours when concentration is added to sensing DETAILED DESCRIPTION OF THE INVENTION While of the exemplary embodiments disclosed herein are described in relation to monitoring glucose levels in peopie with it should be understood that aspects of the invention are useful in monitoring glucose level in people without or for monitoring an analyte or other than For the present invention may be used in the or of other such as acetyl chorionic creatine kinase C growth hemoglobin thyroid stimulating drugs as antibiotics drugs of while invention be described connection it glucose it should be understood that the invention may be used to monitor other analytes as The present provides a significant advance in biosensor and analyte monitoring According to various aspec ts the a glucose monitoring system may be constructed to be virtually integrated have sensors which continuously indicate the glucose enabling swift corrective action to be taken by the The invention may also be used in critical care such in mi intensive care unit to assist health care The sensor and monitor this invention may be used to measure any other analyte as for electrolytes such as sodium or potassium As wtSl be appreciated by persons of skill in the the glucose sensor can be suitable sensor for an electrochemical sensor or an optical One aspect of the invention is a glucose The may comprise a plurality of tissue piercing elements or fluid a sensing zone i fluid with the plurality of tissue piercing elements or fluid a plurality of calibration reservoirs each adapted to hoitse a calibration fluid and fluid with the sensing and a sensor configured to detect glucose and pro vide an indicative of the glucose concentration of the fluid in the sensing 1 illustrate one embodiment of the present Glucose monitor includes fluidic network in which a calibration reservoir is in fluid communication with sensing zone 14 and reservoir 16 to allow for the movement of calibration fluids irom the reservoirs through zone 14 and into the waste reservoir monitor includes an adhesive pad or seal which is coupled to substrate or chip 20 which comprises a plurality tissue piercing elements 22 forming and defining fluid Glucose monitor 10 includes a sensing layer with a fluidic having a calibration reservoir in fluid communication with a calibration fluid adapted to receive calibration fluid from the calibration fluid Calibration fluid channel is in fluid communication with a sensing zone or sensing channel Sensing zone is connected via a check to a waste channel tn fluid communication with a waste reservoir As substrate 20 is coupled to optional adhesive pad for attachment to a When hi the tissue piercing elements 22 each have an inferior space defining a fluid path that passes through the stratum 26 of the skin with a distal opening at distal fluid with the interstitial fluid and a proximal opening at its proximal end 23 in fluid communication with zone and with sensor While not in at least one pump and at least one check can incorporated into the glucose monitor to facilitate or control flow of fluid the calibration fluid reservoir the sensing Also not shown in is an actuator which can be manually or automatically actuated and can be configured to work in conjunction with a pump series of valves to initiate the flow of fluid the fl uid The channels shown in 1 to optional in the glucose as calibration fluid can flow directly from the calibration fluid reservoir into the sensing zone through and further the reservoi One or more waste reservoirs may be incorporated into the glucose the embodiment 1 may include a plurality of calibration calibration reservoirs include a plurality of calibration The calibration fluid which may be the sensing for the calibration fluid does not include one embodiment zone and the tissue piercing elements or fluid paths 22 are wi th sensing fluid prior to the first use of the The sensing fluid may also tilled upon application to the when the device is applied to the skin and the tissue piercing or paths may pierce the stratum and the there is substantially no net fluid transfer from the interstitial fluid into the piercing elements or diffuses from the interstitial into the fluid within the tissue piercing elements or fluid as described Exemplary tissue piercing elements or fluid paths can used with the present invention include US Patent and US Patent Tissue piercing elements or fluid paths and microneedle described in patent application ί filed 2006 may also be An other tissue piercing elements or fluid paths or needle arrays that can penetrate into the epidermis layer and allow glucose to diffuse from the interstitial fluid into the sensing zone of the present in vention may also incorporated into the embodiments described Disposed above and m fluid with is sensor some the sensor is an glucose sensor that generates a eiectricai signal voltage or whose value depends on the concentration of glucose in the fluid zone Details 24 are discussed in more detail Electronics element 28 is configured to receive an eiectricai signal from sensor In some electronics element 28 uses the eiectricai signal to compute a glucose concentration display In other electronics element 28 transmits the electrical or information derived the electrical to a remote such as through wireless Electronics element 28 can comprise other electrical components such as an amplifier and an converter which can amplify the electrical signal from the sensor and convert the amplified eiectricai signal to a digital signal for determining a glucose concentration or transmitting the signal to an external device which then a glucose Glucose monitor 10 can be held in place on the by one or more adhesive pads The glucose monitor has a As shown in the glucose monitor includes one or more calibration reservoirs each adapted to house a calibration The one or more reservoirs are in communication with the sensing A glucose monitor with two or more calibration fluids can have a sensor that can be calibrated at two or more different glucose allows for a calibration curve during the sensor This can provide more accurate calibration curve which in turn can enable a more accurate glucose concentration The calibration fluids in each of the different calibration fluid reservoirs have known and can be different known glucose For in some embodiments a fluid a first calibration iluid reservoir has a glucose concentration of between about 0 mg dl and about 100 and a second calibration fluid in a second calibration fluid reservoir has a glucose concentration of between about 0 and about 400 The ranges of glucose concentrations in the different calibration fluid reservoirs be When more than one calibration fluid reservoir is the calibration fluids in each reservoir may substantially the same or similar glucose some of reservoirs filled a or washing fluid which does not comprise glucose which is not used to calibrate glucose The sensing or washing fluid cm for surfactants and More information about the sensing fluid is provided later in the embodiments in which there are two reservoirs and one comprises sensing and the other comprises calibration the calibration id may have a glucose 0 mg di and 400 and is used to generate a calibration curve for the some the glucose monitor comprises two or calibration fluids reservoirs in addition to a sensing or washing fluid Monitoring a interstitial fluid glucose concentration is further The method can calibrating the glucose sensor or different calibrating fluids with different known glucose A calibration fluid of known glucose concentration is moved into the sensing This be for during manufacture of the prior to the first use by the or any subsequent time ma be desirable io recalibrate the The glucose sensor senses glucose in the calibration fluid the sensing zone and generates signal associated with the known glucose This information ca be used to calibrate operation of the glucose some embodimen any actuating technique described herein then be used to move optional second calibrating fluid with a second known glucose concentration from a second calibration reservoir into the sensing displacing the first calibration into the waste sensor then senses the glucose from calibration fluid in the sensing zone and generates an signal associated the second glucose Using these one or at least two associations of known glucose concentration to glucose sensor a calibration curve plot can be used to associate glucose to the output of the glucose which can then be used to determine glucose concentration of the glucose that diffuses the sensing zone from the interstitial Any number of calibration thus calibration can be used to calibrate the glucose The calibrated sensor is then ready to sense glucose in the sensing zone has diffused from the interstitial Describing the method in relation to upon manual or automatic actuation of actuator fresh calibration fluid is forced from calibration fluid reservoir one reservoir is through check valve such as a flap fluid the sensing zone is generally displaced through second check valve 36 into waste reservoir Check valves or simitar gating systems can also be used to prevent may be advantageous to retain a fluid the lower glucose concentration as first concentration between about 0 mg dl and in the sensing zone after the calibrating to provide for faster response times for the glucose the method described above where second calibration fluid has a higher glucose it may be advantageous to move a of the fresh first lower concentration calibration fluid into the sensing zone after the glucose sensor has been This would move the second sensing fluid from the sensing into waste calibrating can comprise calibrating sensor with a calibration fluid with a higher glucose concentration followed by calibrating the sensor with a calibration fluid a lower glucose Glucose monitors with more than one or more calibration reservoirs have been In at least one can be adapted to house a sensing or washing fluid which does not have any such for a or As used and may be used fluid as used hereto can be a special case of calibrating fluid zero glucose Sensing fluid can be used to displace calibration fluid from the sensing zone after the calibration Glucose would then diffuse from the interstitial fluid into the sensing fluid which does not contain Embodiments in which there are a plurality of calibration fl uid reservoirs as well as at least sensing fluid reservoir are shown in 3 and monitor 10 is shown comprising two calibration fluid reservoirs and one sensing fluid reservoir All three reservoirs are in fluid communication with the An actuator or actuators shown in 3 and be configured to move fresh fluid from the reservoirs into the sensing In some embodiments the sensor calibrated with any number of calibration fluids as described The actuator can then move sensing fluid a sensing fluid reservoir into the sensing displacing a calibration In other the sensor may be calibrated with one calibration fluid and then sensing fluid may be moved into the sensing followed by a second calibration fluid being moved into the sensing displacing sensing fluid and calibrating tiie sensor with second calibrating Fresh fluid can be actuated into the readying monitor for diffusion and glucose In there is a step between calibrating the sensor with fluids of different known glucose yet another embodiment the sensor can be factory calibrated thereby eliminating the need of any calibration fluids within the In some embodiments at least calibration optionally be performed or may be required to performed at any point during th use of monitors described Waste reservoirs may be or include an de vice as a material to absorb waste n such embodiments the waste reservoir may not necessarily be an enclosed but may simply be a material or substance in fluid communication with the sensing zone so that it can waste fluids as they are moved from the sensing While in some embodiments the monitor may be manually actuated to initiate the calibrating the glucose monitor can also be or For the glucose monitor can include a programmable such as a that is programmed to aut acti vate an such as a and valve to initiate the flow of fluid from any of the fluid reservoirs into the sensin The timer can be or in some embodiments die monitor also includes a remote device that is separate the sensor that can display a glucose The remote device can be adapted such it can program the programmable For a patient may want to program the monitor to calibrate itself at certain times during the The monitor can include a timer can be by the automatically The remote device can be adapted for manual some embodiments the glucose monitor includes a body and sensing zone temperature which is more fully in patent application J filed some embodiments the giucose monitor includes a vibration assembly adapted to ease penetration of the needle into the of the Description of exemplary vibration assemblies are described in patent application filed some embodiments the monitor an applicator to apply the sensor pad or adhesive pad to the The applicator be part of the device or when the monitor includes it may be included in any of the different The applicator also be a separate In some the piercing elements or fluid fluid sensing and optional adhesive pads are contained within a sensing structure separate from a reusable structure comprising the electronics element and This configuration permits the comprisin the sensing fluid and tissue piercing elements or fluid paths to be discarded after a period of use the fluid reservoirs are while enabling the reusable structure comprising the electronics and actuator to be A flexible covering of polyester or other may surround and support the disposable In the interface between an actuator and a fluid reservoir permits the aciuaior to move fluid out of the such as by a wall of the reservoir or forcing the fluid of the reservoir using a pressurized such as a these the disposable structure and the reusable structure may have a mechanical such as a snap or interference An of the monitor components described herein be located in the reusable structure or the sensing For the tissue piercing elements or fluid path could be configured to be located in the reusable As another one or more fluid reservoirs may be located in the reusable structure and may be or separately replaceable from other disposable 5 an exploded view of another embodiment of the This figure shows a removable seal 40 covering the distal end of tissue piercing elements or fluid paths and by Removable seal 40 retains the fluid within the tissue piercing elements or fluid paths and sensing zone prior to use and is removed prior to placing the glucose monitor the skin using adhesive seal ibi tissue piercing elements or fluid paths the fluid and waste sensing zone 14 and sensor 24 are contained within supported by sensing structure 42 which can be a disposable portion of the Reusable structure 44 comprises or supports electronics eiement 28 and actuator 32 that can be used to move fluid of the fluid through the sensing zone into the waste Electrical contacts extend from electronics element 28 to make contact for electrodes glucose sensor 24 when the device is The follo wing is a of glucose may he used the glucose of Clark and Lyons proposed the first enzyme electrode was implemented later by Updike and t determine glucose concentration in sample by combining the specificity of a biological sy stem with simplicity and sensitivity of an electrochemical The most strategies for glucose detection are based on using either glucose oxidase or glucose dehydrogenase Electrochemical sensors for based on the specific glucose oxidizing enzyme glucose generated considerable Several devices based on this principie have been developed and are widely used currently tor monitoring of self testing by patients at as well as testing physician offices and The earliest amperometric glucose biosensors were based on glucose oxidase which generates hydrogen peroxide in the of oxygen and glucose according to the following reaction biosensors are used for glucose detection because of their high selectivity and low amperometric detection i based on measuring either the oxidation or reduction of an eieetroactrve compound at a working A constant potential applied to that working electrode with respect to another electrode used as the reference The glucose oxidase enzyme is first reduced in the process but is reoxidized again to its active form by presence of any oxygen resulting in the formation of hydrogen Glucose sensors generally have been designed by monitoring either the hydrogen perox ide formation or the oxygen The hydrogen peroxide produced is easily detected at a potential of or any other fixed potential relati ve to a reference electrode such a a sensors based on hydrogen peroxide detection are subject to electrochemical interference by the presence of other oxtdizable species in clinical samples such as blood or On the other biosensors that monitor oxygen consumption are affected by the variation of oxygen concentration in ambient air or in any of the fluids used with the monitors as described order to overcome these strategies have been developed and Selectively permeable or polymer have used to suppress or from endogenous species in biological Another strategy to solve these problems is to replace oxygen with electrochemical mediators to the Mediators are active compounds that can the and then be at the working electrode as shown Organic conducting ferrocene and ferrocene and are considered good of such Such electrochemical mediators act as couples to shuttle electrons between the enzyme and electrode Because mediators can be detected at lower oxidation potentials than that used for the detection of hydrogen peroxide the interference from electroaetive species and acids in samples such as blood or serum is greatly For example ferrocene derivatives have oxidation potentials in the to V Conductive organic salts such as TC can operate as low as Volts relative to a reference et WO published 3 1 discloses an biosensor system in a fluid containing glucose is contacted with glucose oxidase and The glucose is oxidized and the ferrieyanide is reduced to This is catalyzed by glucose After two electrical potential and a current caused by the of the ferroeyanide to ferrieyanide is The current obtained a few seconds after the potential is correlates to the concentration of glucose in the There are multiple glucose sensors that may used with this In a three electrode shown 6A and 6B a working electrode such as or is referenced against a reference electrode 52 as and a counter electrode such as provides a means for current The three electrodes are an electrode substrate 56 as shown in then covered with a reagent 58 as shown in 7A and show a two eiectrode wherein the working and auxiliary 50 and 60 are made of different electrically conducting Like the embodiment of 6A and the are mounted on a flexible substrate 56 and covered with a 58 in an alternative two electrode the working and auxiliary electrodes are made of the same electrically conducting where the reagent surface area of the auxiliar electrode is slightly larger than that of the working electrode or where both and auxiliary electrodes substantially of equal In and of the enzymes is also very important Conventional methods of enzyme include covalent physical adsorption or to a suitable matrix may be In some the reagent chemistry be deposited away from the electrodes using various different dispensing The glucose sensor can be constructed by immobilizing glucose oxidase enzyme on top of the electrode by using a proprietary cross linker and a The cross linker will hold the enzyme on top of the and the thin layer membrane cellulose polyvinyl will help the long term stability of the In the presence of oxygen the glucose oxidase will produce hydrogen The hydrogen peroxide can be readily oxidized at the working electrode surface in either two or three electrodes In some the reagent is contained in a reagent well in the The reagent includes a redox and a and covers substantially equal surface areas of portions of the working and auxiliar a sample containing the analyte be in this example comes into contact with the glucose biosensor the analyte is and simultaneously the mediator is After the reaction is an electrical difference is applied between the In general the amount of oxidized form of the redox mediator at the auxiliary electrode the applied potential difference must be sufficient to cause diffusion limited electrooxidation of the reduced form of the redox mediator at surface of the working After a time the current produced by the electrooxidation of the reduced form of the redox mediator is measured arid correlated to the amount of the analyte concentration in the some the analyte to be measured may be reduced and the redox mediator may be In the present these elements may be satisfied by employing a readily reversible redox mediator and using a reagent with the oxidized form of the redox mediator in an amount sufficient to insure that the diffusion current produced is limited by the oxidation of the reduced form of the redox mediator at the working electrode For current produced during electrooxidation to be limited by the oxidation of the reduced form of the redox medi ator at the working electrode the amount of the oxidi zed form of redox mediator surface of the auxiliary electrode exceeds the amount of the reduced form of the redox mediator at surface of the working when the reagent includes excess of the oxidized form of the redox as described the working and auxiliary electrodes be substantially the same size or unequal size as well as made the same or different electrically conducting material or different conducting From a cost perspective the ability to utilize electrodes that are fabricated from substantially the same material represents an important advantage for inexpensive As explained the mediator must readily and the oxidized form of the redox mediator must be of sufficient type to receive at least one electron from the reaction involving and oxidized form of the redox For when glucose is the analyte to be measured and glucose oxidase is the or may be the oxidized of the redox Other of enzymes and redox tha t may be used particular aaalytes by the present invention are ferrocene and or ferrocene and Buffers may be used to provide a preferred range from about 4 to I one the range is from about 6 to The buffer may be phosphate and may be in a range from about to such as about concentration ranges refer to the reagent composition before it is dried onto the electrode More details regarding glucose sensor chemistr and operation may be found Clark C and Lyons Systems for Continuous Monitoring in Cardiovascular Ann NY Acad Updike S and Hicks G Enzyme et enzyme electrode r amperometric determination of and et An amperometric enzyme electrode for monitoring brain glucose in the freely moving Neurosci With the above another embodiment of the glucose monitoring device will be The glucose monitor of this embodiment comprises a plurality of fluid each fluid path comprising a distal a proximal opening and an interior space extending between the distal and proximal The glucose monitor further comprises a sensing zone in fluid communication with the proximal openings of the fluid the glucose monitor comprises a fluid extending from the sensing zone substantially die entire interior space of the fluid The sensing fluid comprises a trat ion of the glucose monitor a sensor adapted to detect a concentration of glucose in the sensing fluid within the sensing methods of measuring glucose concentration are described Th methods may be applied to any of the above embodiments of the glucose monitoring Glucose is transported blood to Gkseose diffuses from the fluid in the skin to sensing fluid in lumens tissue piercing elements to other fluid further diffuses through the lumens or fluid paths into the sensing zone filed with sensing As explained glucose reacts with the sensor chemistry to make hydrogen Hydrogen peroxide detected at an electrochemical producing an electrical current aspect of the invention is a method of in vivo monitoring of an interstitial fluid glucose concentration comprising creating a plurality of fluid paths through a stratum corneum layer of an area of the The may also comprise inserting tissue piercing elements through the stratum corneum layer of an area of the The tissue piercing elements may be solid or The tissue piercing elements may then be leaving voids that form fluid paths directl through the stratum corneum the tissue piecing elements may be left in place in the stratum such that fluid paths are formed through or around the tissue piercing As indicated the fluid paths may be by piercing the fl uid paths may also be created by removing layers of the sk in or by placing holes or pores through the the fluid paths may be created with abrasion or The fluid paths each comprise a distal end in fluid communication interstitial fluid of the indi a proximal end fluid communication with a sensing zone located outside of the An interior space extends between the distal and proximal ends of the fluid The interior space may also be referred to as a lumen area in piercing elements or fluid A sensing fills substantially the entire interior space and the sensing fluid concentration comprises a concentration of some the concentration of citrate ranges from 100 per liter to 200 other the concentration of citrate ranges from 135 to In another variation the concentration of citrate ranees raM to 250 where the adjusted based the desired of time to in the A citrate can refer to citric acid or any conjugate base of citric acid The sensing fluid also comprises a buffer Th buffer formulation be comprised of phosphate and citrate or other The method allows at least one analyte to passively diffuse from the interstitial fluid through the tissue piercing elements or fluid paths and the se sing The analyte is glucose another agent that is being transdermally monitored through the fluid paths or tissue piercing In additional an methods and devices can include allowing at least one analyte to passively diffuse from the interstitial fluid through micropores created fay tissue piercing where the piercing elements have The are in fluid communication with the sensing zone and remain in fluid communication due to the concentration of citrate discussed i some embodiments of the method increase initial transdermal glucose flux and inhibit a decrease over time in transdermal glucose flux or of another agent that is being monitored through the tissue piercing elements or fluid Flux enhancement ma be achieved by addition of citrate to a saline phosphate buffered solution in the sensing Measurement of the glucose can used to determine whether the micropores remain Failure to detect glucose can indicate that the micropores are closed or the systems and devices can be configured to monitor the glucose flux to determine that it remains The method may then mitigate a decrease of the transdermal analyte fluid through the fluid paths after the step of increasing transdermal analyte fluid The may last up to 72 hours or more The method further comprises sousing a concentration of the at least one analyte in a sensing fluid within the sensing zone using a sensor located at least partially in the sensing In glucose concentration is sensed using the Addition of citrate to the PBS buffer results in the following benefits compared to the increased transdermal through the tissue piercing elements or paths immediately after application of the tissue piercing elements or fluid paths to inhibition of a transdermal flux several hours after and inhibition of a decrease transdermal flux up for several days after 8 illustrates an av erage ratio of transdermal glucose to reference blood glucose measurement for sensing blood As illustrated in results were taken as tissue piercing elements of glucose monitoring devices were applied to the skin and samples were collected in 100 uL sensing Eight control devices without citrate sensing fluid concentration in the sensing zone and eight devices with citrate sensing concentration in the sensing zone were the sensing zone was filled with either 300 Phosphate PBS or 300 raM Phosphate 53 mM Samples of glucose were taken every 20 minutes for six Reference blood glucose measurements were taken at the same intervals of every 20 minutes for six For each the ratio of transdermal glucose through the tissue piercing elements to the corresponding reference blood glucose was Flux ratios were averaged over the sampling period by each glucose monitoring Mean flux ratios averaged by buffer condition are shown in As the addition of citrate resulted in a statistically significant increase in transdermal glucose the value being of mean flux ratio compared to the control of mean flux ratio 9 illustrates change in ratio of transdermal glucose flux to reference blood glucose per hour for sensing blood glucose Eigh control devices citrate sensing fluid concentration in the sensing zone and eight devices with citrate sensing concentration in the sensing zone were the sensing zone was filled with either 300 mM Phosphate PBS or 300 mM Phosphate mM Signal decay was measured as the change flux ratio per hour as a percentage of the initial flux Flux ratio change per hour by condition shown in The addition of citrate resulted in a statistically significant inhibition of signal decav compared to the control devices illustrates percentage of initial transdermal glucose flux after 24 hours of glucose monitoring device Ten control devices without citrate sensing fluid concentration in the sensing zone and thirty one devices with citrate sensing fluid concentration in the sensing zone were at 24 hours as a percentage of initial flux the first two is shown in averaged for the two buffer with and without citrate The addition of raM citrate resulted in a statistically significant in percentage of initial flux at 24 compared to the control devices 1 illustrates percentage of initial glucose flux after hours of glucose monitoring device Eight control devices without citrate sensing fluid in sensing zone and eight devices with citrate fluid concentration in the sensing zone were provided Flux at 48 and hours as a percentage of initial flu the first two is shown in for each of the two buffer with and without citrate The addition of 153 citrate resulted in a statistically increase in percentage of initial flux at 24 hours 8 hours and 72 hours compared to the control After glucose monitoring device removal the stratum corneum layer of an area of the blockage of the tissue piercing elements lumens was Tissue piercing elements were placed on a light Imaging of the on the other side of the tissue piercing elements was and 12b illustrate images of tissue piercing element lumens after use sensing fluid for 72 12a shows lumens used with a control sensing fluid having no citrate shows lumens used with a fluid ha ving citrate to the buffer As shown in 12a and glucose monitoring devices with citrate added to the buffer had significantly less lumen occlusion than the control device without the 12a and dimensions are approximately as measured by these photographs may mean filled with opaque material so that light may not be In terms of may mean filled with material so that transport of the analyte through the lumen is substantially hindered or Occlusion may be caused by protein adsorption in the lumen or near the distal end of the deposition of material via clotting fibrin In and the citrate condition has open lumens and the condition has open lumens illustrates percentage of unblocked tissue piercing element lumen area within 24 and 72 hours when citrate concentration is added to the sensing A series of studies was performed investigating the effect of the addition of citrate on tissue piercing element lumen Glucose monitoring devices were applied and removed at 24 hours or 48 The results are reported as a percentage of the expected total lumen measured Higher percentages of lumen area were observed both 24 hours 48 hours far the citrate illustrates percentage of open tissue piercing element within 72 hours when citrate is added to the sensing A series studies was performed investigating the effect of the addition of citrate tissue elements lumen Devices were applied and removed at The results are reported as a percentage of the number of Addition of citrate resulted in significantly higher number of open lumens to the control At 72 citrate devices had all or lumens with unblocked While exemplary embodiments of the present invention have and described it will be obvious to those skiiled the art that such embodiments provided by way of example Numerous and substitutions will now occur to those skilled the art without departing from the should be understood that various alternatives to the embodiments of the invention described herein be employed in practicing the is intended that the following claims define the scope of the invention and that methods structures within the scope of these claims their equivalents be covered insufficientOCRQuality