Vernier ECG for NI ELVIS II

Publish Date: Oct 30, 2011 | 1 Ratings | 4.00 out of 5 | Print | 1 Customer Review | Submit your review

Overview

Students learn basic concepts of acquiring and analyzing an electrocardiogram (ECG or ECG) usnig the Vernier’s ECG sensor. This lab also introduces the Biosignal Logger and ECG Feature Extractor of the NI Biomedical Startup Kit.

Theory

Your heart is initially polarized at rest due to the excess of sodium ions (Na+) outside of the membrane. This correlates to a resting potential of approximately 90 mV. Muscle stimulation increases the permeability of the membrane to these sodium ions. The entry of these sodium ions into the membrane alters the electric field around the muscular cells, generating an action potential and causing muscle contraction. Other ions, including potassium, calcium, and chlorine are also involved in this process. Electrodes placed on the surface of the skin record a summation of these action potentials. The resulting signal can be graphed as an electrocardiogram (ECG or ECG) and illustrates cardiac electric potential. Various deflections in the ECG waveforms correspond to the contraction of different areas of the heart. Each heart cycle is represented by a P wave, a QRS complex, and a T wave. The P wave corresponds to the depolarization of the atria, the QRS complex corresponds to the depolarization of the ventricles (repolarization of the atria also occurs during this time), and the T wave corresponds to the repolarization of the ventricles. Refer to Figure 1 below for a typical ECG signal and the typical time spans for each deflection.

(Summarized from the ECG Sensor User Guide; http://www.vernier.com)

 

 

Figure 1: Typical ECG Signal

(www.vernier.com)

P-R interval:  0.12 – 0.20 seconds

QRS interval:  < 0.1 seconds

Q-T interval:  < 0.38 seconds

 

The ECG sensor used in this lab utilizes three electrodes, which are attached to the surface of the skin. There is an internal offset of 1 V within the sensor with an accuracy of +/- 0.3 V. This lab is set to account for this offset. The gain of the ECG sensor is set to amplify a 1 mV measured potential to a 1 V output. Reference the ECG sensor user guide for more information.

 

Materials

  • NI Biomedical Startup Kit 3.0
  • NI ELVIS II Series Benchtop Workstation
  • NI ELVIS II Series Prototyping Board
  • AC/DC power supply
  • NI ELVISmx 4.0 or later
  • High-speed USB 2.0 cable
  • Computer
  • Wires to build circuits
  • Vernier Analog Proto Board Connector  (order code BTA-ELV)
  • Vernier ECG Sensor (order code ECG-BTA)

 

Additional Resources

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Customer Reviews
1 Review | Submit your review

  - May 11, 2012

there should be correction in the wire connection. It should be, 1. AI0+ to SIG1 of the Analog Proto Board Connector 2. +5V DC power supply to 5V of the Analog Proto Board Connector 3. GROUND power supply to GND of the Analog Proto Board Connector 4. AI0- to GND of the Analog Proto Board Connector Thanks to this: http://forums.ni.com/t5/Academic-Hardware- Products-NI/How-to-use-Vernier- Bioinstrumentation-Sensor-kit-with-the-NI/m- p/1781170

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