Glucose Biosensors - PowerPoint PPT Presentation


PPT – Glucose Biosensors PowerPoint presentation | free to view - id: 4578d7-Njg5M


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation

Glucose Biosensors


... Enzymatic Reactions for Glucose Analysis Thermometric Sensors Thermopile-based Enzyme Probe Optical Sensors Electrochemical Sensors So Why Is This Useful? – PowerPoint PPT presentation

Number of Views:2104
Avg rating:3.0/5.0
Slides: 13
Provided by: Ama362


Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Glucose Biosensors

Glucose Biosensors
Presented by
Jay Leitch
What are Glucose Biosensor?
  • Immobilized biological components fixed on
    ordinary analytical detectors
  • Selectively detects and quantifies the analyte
    in a natural matrix without requiring any
  • Ideal Sensor
  • Highly Specific
  • Linearity in signal response
  • Independent of hydrodynamics
  • Independent of co-substrates
  • Requires minimal calibration
  • Biocompatible
  • Long lifespan
  • Low cost
  • Can be scaled down

Biosensor Components
  • Membranes
  • Used to protect immobilized GOD electrodes from
    high metabolite concentration. Extends linearity
    of sensor by limiting glucose, but not O2
  • E.g. Polyurethane (PU), Perforated, Polycarbonate
  • Transducers
  • Thermometric
  • Optical fluorescence, chemiluminescence,
    optical rotation
  • Electrochemical potentiometric, voltammetric,
  • Biological Component
  • Biocatalytic Mediator enzyme/antibody etc. that
    interacts with the desired analyte

Enzymatic Reactions for Glucose Analysis
glucose oxidase
  • Glucose O2 Gluconic acid H2O2 19 kcal
  • H2O2 ½ O2 H2O 24 kcal
  • Total Reaction
  • Glucose ½ O2 Gluconic acid H2O 43 kcal
  • Glucose oxidase (GOD) is commonly used since it
    fairly stable requires no cofactors or

Thermometric Sensors
  • Measures heat changes caused by enzymatic
  • Limited to in vitro analysis
  • Transducers
  • Thermistor very sensitive, but excitation
    electricity causes a raise in thermister
    temperature, thus strict control over ambient
    temperatures is needed
  • Thermocouple no excitation electricity, but
    low sensitivity
  • Thermopile Antimony and Bismuth evaporated
    in thin film creating a series array of
    thermocouple junctions. Sensitivity increases
    with the number of junctions. Do not require
    excitation electricity

Thermopile-based Enzyme Probe
Optical Sensors
  • Can measure aqueous glucose concentrations by
    optical emissions by using fluorescence,
    chemiluminescence and optical rotation of
  • Advantages
  • Electrical isolation from patient
  • Eliminates electrical interference
  • No need for a reference electrode
  • Easily miniaturized due to advances in fiber

Bioaffinity glucose sensor glucose binds to con
A (concanavalin A) releasing a fluoroesceinated
dextran. Range of measureable glucose levels
2.8-22 mM. Response time 5-7 min.
Electrochemical Sensors
  • commonly measured by amperometric or
    potentiometric methods
  • composed of electrode with enzyme, such as GOD
    immobilized and surrounded by PU membrane
  • can monitor glucose levels by examining reaction
    substrates or products
  • can be miniaturized easily and produce effective

So Why Is This Useful?
  • Many individuals in the world are diagnosed with
    Diabetes Mellitus
  • Diabetes mellitus is a disease that affects the
    production or release of insulin
  • Chronic elevations of blood glucose can lead to
    renal, retinal and neural complications
  • Traditionally glucose levels could be monitored
    using capillary blood from finger prick and using
    GOD/peroxidase dry reagent strips and insulin
  • Implantable glucose sensors could be a solution
    to prevent insulin shock and diabetic coma

Implantable Glucose Sensors
  • Continuous monitoring of analyte concentration
  • Sensor signal coupled to an infusion pump for a
    closed-loop insulin delivery (i.e. forming an
    artificial pancrease)
  • Usually implanted in subcutaneous tissue
  • Based on electrochemical or optical techniques
  • 3 Basic Designs vessel-shaped blood flows
    through it
  • needle type injected by needle
  • plane-geometry see figure below

Glucose Sensor Implant Results
  • Implant showed a linear trend between sensor
    output and glucose concentration
  • 95 accurate
  • Only a slight lag (60 secs.) between increased
    glucose and signal
  • Fairly Sensitive
  • Showed no effects in the presence of inhibitors
  • Problems
  • Short lifespan performance impaired in 3-7
    days and need replacing after 4 weeks
  • Eliminating lag would be ideal since high
    glucose levels for even one minute good
    potentially cause damage
  • Glucose concentration is lower in subcutaneous
    interstitial fluids than in bloodstream

  1. Cunningham, A. Introduction to bioanalytical
    sensors. New York John Wiley Sons, Inc.
    1998, pp.159-62
  2. Turner,A. Advances in Biosensors. Vol.1 England
    Jai Press Ltd. 1991, pp.67-72.
  3. Ward, W. et. al. A new amperometric glucose
    microsensor in vitro and short-term in vivo
    evaluation. Elsevier Science. Biosensors
    Bioelectronics 17 (2002) 181-189.
  4. Wilson, G. et. al. Biosensors Fundamentals and
    Applications. New York Oxford University Press,
    1989, pp.390-405.
  5. Wise, L. Bioinstrumentation and Biosensors. New
    York Marcel Dekker, Inc., 1991, pp.229-45.
  6. Wise, L. Applied Biosensors. Boston
    Butterworth Publishers, 1989, pp.227-44.