Shimmer 3 User Manual

Ecg

Hide thumbs Also See for 3:

User manual (76 pages)

Getting started (18 pages)

Getting started (12 pages)

Table Of Contents

Quick Links

Download this manual

Realtime Technologies Ltd

IMU User Manual

Rev 1.1

ECG User Guide

Revision 1.12

Table of Contents

Troubleshooting

Need help?

Do you have a question about the 3 and is the answer not in the manual?

Questions and answers

Summary of Contents for Shimmer 3

Page 2 Neither the name of Shimmer Research, or Realtime Technologies Ltd. nor the names of its contributors may be used to endorse or promote products derived from this document without specific prior written permission.
Page 3: Table Of Contents
Copyright © Shimmer 2018 Realtime Technologies Ltd ECG User Guide All rights reserved Rev 1.12 Table of Contents Introduction ..........................4 General Information ......................... 5 2.1. Safety Information ......................5 2.2. Pre-Requisites ........................5 2.3. ECG Unit Specification Overview ..................5 Using the ECG Unit ........................
Page 4 Copyright © Shimmer 2018 Realtime Technologies Ltd ECG User Guide All rights reserved Rev 1.12 Gain Measurement ........................20 Hardware Considerations ......................20 5.1. Board Layout ........................20 5.2. Channel assignment ......................22 5.3. Data considerations ......................23 Firmware Considerations ......................23 Troubleshooting ........................
Page 5: Introduction
The ECG Unit can be configured to measure electrical signals from the skin, including ECG (Electrocardiograph). Any user who wishes to use Shimmer hardware to record EMG (Electromyograph) signals from the skin should refer to the Shimmer3 EMG User Guide, which is available for download from http://www.shimmersensing.com.
Page 6: General Information
2.3. ECG Unit Specification Overview  For specifications on the general Shimmer3 part (i.e. microprocessor, radio, data storage and inertial sensors) of the Shimmer3 ECG Unit, please refer to the Shimmer User Manual.  Gain: Configurable (1, 2, 3, 4, 6, 8, 12) ...
Page 7: Using The Ecg Unit
Realtime Technologies Ltd ECG User Guide All rights reserved Rev 1.12 3. Using the ECG Unit 3.1. Basic System Overview Figure 3-1: Simplified Block Diagram  Electrodes: Each ECG board connects to RA (white), LA (black), RL (green), LL (red) and Vx (brown) electrodes.
Page 8: Ecg Leads
Copyright © Shimmer 2018 Realtime Technologies Ltd ECG User Guide All rights reserved Rev 1.12 3.2. ECG Leads In the context of electrocardiography, the word "lead" is used to refer to the signal of the voltage difference between two electrodes (i.e. the signal produced by the ECG recorder). In order to avoid any confusion, the wires that are used to physically connect the electrodes to the ECG Unit are referred to throughout this document as just that - "wires".
Page 9 Figure 3-3: Example positioning of the electrodes for ECG measurement with 9” leads Figure 3-2 shows an example of how the electrodes should be positioned on the body. The electrodes for the bipolar limb leads (LA, RA, LL and RL) are represented by green nodes and wires,...
Page 10: Wilson's Central Terminal
The reference electrode (RL) can be placed anywhere on the body as long as it is outside of the triangle formed by the 3 other limb electrodes (i.e. RA, LA and LL). In the diagram below it is placed at the V position, laterally on the left side of the torso.
Page 11: Data Rate
The gain bits for channel 1 of a given chip are listed as G1_2 (MSB), G1_1 and G1_0 (LSB) in Table 3-1, whilst the equivalent for channel2 of the chip are listed as G2_2, G2_1 and G2_0, respectively. These are collectively referred to as Gx_2, Gx_1 and Gx_0, respectively, in Table 3-3, which lists the valid options and the corresponding gain value for each.
Page 12: Input Multiplexer
Table 3-1. For ECG configuration, the recommended setting is to choose the Wilson's Central Terminal voltage ((RA + LA + LL)/3) as the negative input to the RLD amplifier on Chip1 and no RLD signal on Chip2. This can be achieved by setting the configuration listed in Table 3-5.
Page 13: Test Signal
DC voltage or a 1Hz square wave. The enable the test signal, the two LSBs of the CONFIG2 byte (byte 1, bits 1-0) for each chip should be set as in Table 3-8. Furthermore, the MUX1 or MUX2 bits should be set to 0000 so that the test signal will appear on channel 1 or channel 2, respectively.
Page 14 The level of DC current used for lead-off detection can be set by changing configuration bytes as shown in Table 3-10. From lab testing we have found 22nA to be a suitable level for lead-off detection. Chip 1 - Byte 2 and Chip 2 Byte 2...
Page 15: Measuring Ecg Signals
Chip 2 - Bit2 Chip 1 - RL Chip 1 - Bit4 Table 3-12 The relevant bits in each of the status bytes that represent the lead-off status of each of the electrodes for ECG mode. 4. Measuring ECG Signals 4.1.
Page 16: Basic Ecg Waveform Features
The APIs and Instrument Drivers, provided by Shimmer for development of software in Java/Android, LabVIEW, Matlab and C#, include the implementation of optional high pass filtering in the example code.
Page 17: Example Hr Calculation
= 843, S = 331, F = 512 Hz. HR = 60*(2-1)/((843-331)/512) = 60 BPM. Figure 4-2: Diagram of ECG signal captured with ‘Multi-Shimmer Sync’ for HR calculation example. Figure 4-3: Diagram of ECG signal and derived HR signal using ConsensysPRO software...
Page 18: Overview Of Popular Qrs Detection Methods
Please note that free software solutions for QRS detection analysis are not currently provided by Shimmer and the information below is intended as a starting point for the new user to aid their software development. Should you require a ‘pre-packed’ software solution, please contact the Shimmer team to discuss it further (www.shimmersensing.com).
Page 19: Aliasing Error And Sampling Rate
At low sampling rates, ECG signal quality is significantly reduced. One effect of this is R wave height variation. Figure 4-3, Figure 4-4 and Figure 4-5 below show a 30 BPM ECG recording at 102.4Hz, a 60 BPM recording at 204.8Hz and an 120 BPM recording at 512Hz respectively. It is noticeable that the variation in R wave height variation is minimised with increased sampling frequency.
Page 20: Signal Calibration
Considering that the ADC sensitivity is known and that the ADC Output is measured from the Shimmer, in order to calculate the ECG signal in mVolts, the values for the Gain and ADC Offset must simply be inserted into Equation 2.
Page 21: Adc Offset Measurement
The ADC offset for the Lead II channel is then calculated as the mean ADC output on the ECG LL-RA channel of the Shimmer with the RA and LL inputs connected together. This can easily be found by saving uncalibrated data to a file and then calculating the mean value. The offset for other channels is calculated similarly.
Page 23: Channel Assignment
Rev 1.12 Figure 5-2: ECG Board Layout (top view) 5.2. Channel assignment When the MUX settings recommended in Section 3.3 of this document are configured, the channel assignment for ECG is as follows:  Chip1 Channel 1: (LL - RA) J14 (Red) - J10 (White).
Page 24: Data Considerations
To verify that your ECG Unit is functioning correctly, the test signal in the ADS1292R chips should be used. Please refer to Section 3.3 of this document for details on how to configure each chip to output the test signal on one or both channels. When the test signal is configured, the output of each channel should follow the signal exactly (i.e.
Page 25: References
[2] Smith, M. “Rx for ECG monitoring artifact.” Critical Care Nurse, 1984(4), p64-66. [3] Pizzuti GP, Cifaldi S, Nolfe G (1985) ‘Digital sampling rate and ECG analysis’. [4] Thaler, M.S. (2007) The only EKG book you’ll ever need, 5 ed., Philadelphia: Lippincott Williams &...
Page 26: Appendices
Copyright © Shimmer 2018 Realtime Technologies Ltd ECG User Guide All rights reserved Rev 1.12 9. Appendices 9.1. Legacy Hardware The information in this section is relevant for Shimmer3 ECG hardware purchased prior to July 2015. The figures in this section show the board layout for the ECG Module, with components labelled. The two ADS1292R chips are labelled EU1 and EU2 and are referred to in the documentation as Chip1 and Chip2, respectively.
Page 27: Channel Assignment
Rev 1.12 Figure 9-2: ECG Board Layout (top view) Channel assignment When the MUX settings recommended in Section 3.3 of this document are configured, the channel assignment for ECG is as follows:  Chip1 Channel 1: (LL - RA) J4 (Red) - J1 (White).
Page 28: Opening The Shimmer3 Expansion Enclosure
Superdots also provides some shock absorbtion. Shimmer fits the Superdots by stretching them around the edges of the Expansion Board. This ensures that the adhesive doesn't prevent the connectors from making a good connection and there is enough adhesive to secure the boards together but not to interfere with the fit.