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How the Glucose Sensor Works Continuous Glucose Monitoring.

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Presentation on theme: "How the Glucose Sensor Works Continuous Glucose Monitoring."— Presentation transcript:

1 How the Glucose Sensor Works Continuous Glucose Monitoring

2 Objective To learn the components of the Glucose Sensor and how the Glucose Sensor works in interstitial fluid Key Points Proper technique when handling and inserting the Glucose Sensor as well as ongoing care leads to a successful CGM experience The Glucose Sensor requires calibration with a blood glucose meter

3 Glucose Sensor Components Introducer Needle Sensor Electrode inside the needle Connector to MiniLink or iPro Body Introducer Needle Handle

4 Glucose Sensor Components Sensor Electrode inside the needle Pick up the Sensor on either side of the Connector Body Never hold or pick the Sensor up by the needle handle Introducer Needle Handle Attaches to the MiniLink Transmitter or iPro Recorder Connector Introducer Needle –22 gauge (1/2 diameter) –Bevel faces down –Discard after insertion

5 The Sensor Electrode Sits Inside the Introducer Needle Reference electrode Counter electrode Working electrode Maintaining an Optimal Sensor Placement Ensures Success Closest to the skin

6 Layers of the Glucose Sensor Semi Permeable Membrane Selective to glucose and oxygen Enzyme The membrane surrounds a glucose oxydase enzyme Electrode Membrane Enzyme Electrode

7 Outermost Layer of the Glucose Sensor Semi Permeable Membrane Selective to glucose and oxygen Enzyme Electrode Membrane Ensures biocompatibility Maintains the required glucose to oxygen ratio required for diffusion to the enzyme layer Functions as a glucose limiting membrane

8 The Glucose Sensor Consists of 3 Layers Semi Permeable Membrane Selective to glucose and oxygen Enzyme The membrane surrounds a glucose oxydase enzyme Electrode

9 Glucose and Oxygen Enter Membrane 1 Membrane Enzyme Electrode A semi permeable membrane that is very selective to glucose and oxygen The Membrane is required for biocompatibility In subcutaneous tissue Glucose = 72 to 360 mg/dl Oxygen = 0.9 mg/dl Glucose is 5 times more prevalent in subcutaneous tissue

10 Glucose and Oxygen Enter Membrane 1 When the glucose and oxygen come in contact with the glucose oxidase enzyme, the first chemical reaction takes place Glucose and Oxygen Membrane Enzyme Electrode

11 Glucose and oxygen come in contact with the glucose oxidase enzyme Glucose and oxygen are converted into Hydrogen Peroxide (H 2 O 2 ) and gluconic acid First Chemical Reaction 2 Membrane Enzyme Electrode Gly Acid H2O2H2O2 Glucose and Oxygen

12 H 2 O 2 seeps through to the Electrode layer A voltage is applied to the Electrode, causing H 2 O 2 to breakdown into:  Hydrogen  Oxygen  2 electrons Second Chemical Reaction 3 Membrane Enzyme Electrode H2O2H2O2 2e- The more glucose in your body, the more H 2 O 2 generated. The more H 2 O 2, the more current generated.

13 The ISIG is Proportional to Glucose Concentration Converting ISIG to a Glucose Sensor Value The 2 electrons generate a current called ISIG ISIG is converted to a sensor glucose value when a BG meter value is entered into the pump or monitor for calibration 2e- Membrane Enzyme Electrode ISIG

14 2 Converting ISIG to a Glucose Sensor Value Sensors require calibration using a blood glucose meter 13  Check glucose level with a BG meter  The insulin pump or monitor calculates the calibration factor:  Enter BG reading into the insulin pump or monitor  Accept BG reading as a calibration Cal Factor Meter BG / ISIG

15 Converting ISIG to Sensor Glucose ISIG Meter BG Cal Factor = Meter BG / ISIG 108 mg/dL / 10.8 (ISIG) = 10 2e-

16 Calibration Factor Examples Meter BG Glucose / ISIG = Cal Factor 108 mg/dL / 10.8 (ISIG) = 10 (Cal Factor) 10 (Cal Factor) x 10.8 (ISIG) = 108 mg/dL Cal Factor x ISIG = Glucose Example: Cal Factor = 10 ISIG BG (mg/dL) 2e- ISIG = calibrated00:05 min00:10 min e


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