Experiment BI-1: ECG Signal Conditioning

Transcription

1 Experiment BI-1: ECG Signal Conditioning Equipment Required PC Mac Computer IX-TA-220 data acquisition unit and power supply USB cale ire-b3g ECG cale and electrode lead wires C-DIN-BB: Din to Breadoard cale C-BNC-BB: BNC to Breadoard cale A-BREADBOARD: Breadoard. Alcohol swas Disposale ECG electrodes Start the Software 1. Click on Scrie 2. Click Settings BioInstrumentation ECGFilter 3. Once the settings file has een loaded, click the Experiment utton on the toolar to open any of the following documents: Appendix Background s Setup (opens automatically) ECG Cale Setup Insert the connect on the end of the ire-b3g ECG cale into the ire 1 input on the front of the IXTA. Note - Connect the ire-b3g to the IXTA pri to turning it on. 2. Insert the connects on the red, lack, and green electrode lead wires into the matching sockets on the ECG cale. 3. Instruct the suject to remove all jewelry from their wrists and ankles. Another option is to use the area just under each clavicle which will give a etter recding. 4. Use an alcohol swa to clean and scru a region with little no hair, on the inside of the suject s right wrist/clavicle. Let the area dry. BI-1-1

2 5. Remove a disposale ECG electrode from its plastic shield, and apply the electrode to the scrued area on the wrist under the clavicle. 6. Repeat Steps 5 and 6 f the inside of the left wrist/clavicle and the inside of the right ankle lower right adomen. 7. Snap the lead wires onto the electrodes, so that: the red (+1) lead is attached to the left wrist just under the left clavicle, the lack (-1) lead is connected to the right wrist just under the right clavicle, the green (C ground) lead is connected to the right leg on the adomen. Breadoard Setup 8. Instruct the suject to sit quietly with their hands in their lap. If the suject moves, the ECG trace will move off the top ottom of the screen. If the suject moves any muscles in the arms upper ody, electromyogrs (EMGs) from the muscles will appear on the ECG recding as noise. 1. Insert the BNC connect on the end of the C-BNC-BB cale into the S1 stimulat pt of the IX-TA Connect the other end of the C-BNC-BB cale to the readoard. 3. Insert the DIN8 connect of the C-DIN-BB cale into the A5 pt of the IX-TA Connect the other end of the C-DIN-BB cale to the readoard. BI-1-2

3 Design the Filter Circuit Here is an ex of a filter circuit f a 2 pole low pass filter. Circuit BI-1-3

4 The Filter is a Sallen Key 2-pole low pass filter. Its jo is to remove 60Hz electrical noise picked up from fluescent lights, computers and AC power lines. It is immented here on the readoard. BI-1-4

5 Setting up Scrie The provided ECGFilter Scrie setting file has een preset with the following settings. The instructions here are f your infmation and to help you modify other x la experiments to add the option f additional signal conditioning. Open the Preferences dialog, y choosing Edit Preferences from the Main Menu. Channels Ta. Enale the Channels to e recded and el them. These channels will e used: A5 (Filtered ECG): This is the output of the Filter i1 2 (Raw ECG): This is the ECG measured y the ire-b3g S1 (Stimulat): This is what the Stimulat is outputing, which is se as the Raw ECG Channel. You do not have to enale this channel. BI-1-5

6 Stimulat Ta Choose S1 stimulat Set the mode to Analog Channel Choose A12: Raw ECG as the analog channel to e send to the Stimulat output Enale Start Stimulat with Recding. Exercise 1: The ECG and LowPass filter Aim: To recd an ECG and low pass filter the signal to reduce 60 Hz noise. Procedure 1. Click on the Recd utton, located on the upper right side of the Scrie Main window. The signal should egin scrolling across the screen. Note: If the user clicks the Recd utton and there is no communication etween the x unit and computer, an err window will appear in the center of the Main window. Make sure the x unit is turned on and connected to the USB pt of the computer. Click OK and select the Find Hardware function from the Scrie Tools menu. 2. Click on the AutoScale All utton on the Scrie toolar, to Autoscale all the channels. BI-1-6

7 3. Recd f a minute two. 4. Click Stop to halt the recding and click File Save As to save your data file. Channel A12: Raw ECG is the Raw ECG signal recded y the ire-b3g. Channel S1: Stim 1 is the output of the Stimulat that is send to the readoard Channel A5: Filtered ECG is the Filtered output of the ECG signal, after signal conditioning on the Breadoard. 5. The signals on A12 and S1 are the se, and have some 60Hz noise. 6. The Filtered Signal is recded on Channel A5. The 60 Hz noise has een filtered out with the 2 pole low pass filter, as set accding to the Setup PDF document. BI-1-7

8 Optional Exercises: The ECG and Signal Conditioning. Extend the first exercise to test other signal conditioning that can e perfmed on the ECG signal. F ex: 1) What happens if you use a 4 pole filter instead of a 2 pole filter? 3) What happens if you use a high pass filter? 4) What happens if you use a and pass filter? 2) What happens if you use a different topology f the filter? 5) What filter cutoffs are est at reducing the noise ut still maintain the signal? BI-1-8