Electrochemical Glucometers

Electrochemical Glucometers Is a type of electrochemical transducer - measuring current out-put at fixed voltage, a technique known as amperometryGlucose

Blood Glucose

1. http://www.diabetes.org/diabetes-basics/type-2/facts-about-type-2.html3Electrochemical Glucometers

1. http://electrochem.cwru.edu/encycl/art-g01-glucose.htm4Traditional Electrochemistry

Leary and Skoog. Principles of Instrumental Analysis. Orlando: Sauders College Publishing (1992).

5Chemical ReactionsOxidation of Glucose by EnzymeMediator transports electrons to working electrodeFerrocene monocarboxylic acid (Fecp2R)glucose + GOD(ox) gluconolactone + GOD(red)

glucose gluconolactone + 2e-2e- + GOD(ox) GOD(red)D-glucoseCass, Anthony E. G. Analytical Chemistry. (1984)56:667-671

Ferrocene-mediated enzyme electrode for amperometric determination of glucose

6Reduction of Enzyme by MediatorGOD(red) + 2Fecp2R+ GOD(ox) + 2Fecp2R + 2H+2Fecp2R 2Fecp2R + 2e-

Ferrocene

Test Strips1. http://electrochem.cwru.edu/encycl/art-g01-glucose.htm8

amperometryAmperometry in chemistry and biochemistry is detection of ions in a solution based on electric current or changes in electric current.Amperometric bio-sensors are based on Amperometric technique.

Amperometric Analysis1. http://electrochem.cwru.edu/encycl/art-g01-glucose.htm

Cass, Anthony E. G. Analytical Chemistry. (1984)56:667-671

Ferrocene-mediated enzyme electrode for amperometric determination of glucose

11AdvantagesFastDisposable StripNo Instrument ContaminationDisadvantagesDiscomfort of pricking fingerNon-continuous measurement1. Newman, Jeffery D. And Anthony P.F. Turner. Biosensors and Bioelectronics. (2005)20:2435-2453.Home blood glucose biosensors: a commercial perspective 12Implantable Glucose SensorAdvantage: continuous glucose monitoring Could be coupled with continuous subcutaneous insulin infusionsProblems:Sensor stabilityCalibrationBiocompatibility 1. Newman, Jeffery D. And Anthony P.F. Turner. Biosensors and Bioelectronics. (2005)20:2435-2453.Home blood glucose biosensors: a commercial perspective

13Recent Study

Designed Implantable sensor recorded glucose values every 128 sLongest sensor (of 5 subjects) lasted 103 days in vivo!1. Gilligan, Barbara J. et. Al. Diabete Technology & Therapeutics. (2004)6:378-388. Feasibility of Continuous Long-Term Glucose Monitoring from a Subcutaneous Glucose Sensor in Human14Implantable electrochemical glucometers would allow for continuous measurement of blood glucose levels.This technology has the potential of being couple with continuous subcutaneous insulin infusions which could deliver insulin to a patient automatically.in a recent study by Barbara Gillian et. al. was able to construct an implantable electrochemical glucosensor that lasted over 100 days in vivo.In this study, the designed glucosensor was able to record blood glucose levels every 128 seconds and were highly corelated with lab monitors and two common glucose monitors (see left).While implantable glucosensors show promise, problems arise with:Sensor stability

CalibrationBiocompatability (rejection): Immunorespons

Glucometer Simplified Circuit Diagram

OOH

OH

OH

OH

HO