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UnoViS: The MedIT Public Unobtrusive Vital Sign Database

Motivation

While PhysioNet is a large database for standard clinical vital sign measurements [1], such a database does not exist for unobtrusively measured signals. This hinders progress in the vital area of signal processing for unobtrusive medical monitoring as not everybody owns the specific measurement systems to acquire such signals. Furthermore, if no common database exists, a comparison between different signal processing approaches is not possible. This gap will be closed by our UnoViS database. It contains different measurements in various scenarios ranging from a clinical study to measurements obtained while driving a car.

Initially, 145 records with a total of 16.2 hours of measurement data were made available, provided as MATLAB files or in the PhysioNet WFDB file format. In its initial state, only capacitive ECG and unobtrusive PPG signals were, together with a reference ECG, included. The dataset from the clinical study contains clinical annotations. Additionally, supplementary functions are provided, which simplify the usage of our database and thus the development and evaluation of new algorithms. The development of urgently needed methods for very robust parameter extraction or robust signal fusion in view of frequent severe motion artifacts in unobtrusive monitoring is now possible with our database.

An example for the severe motion artifacts and the opportunities of a multichannel unobtrusive monitoring is shown in the following figure. While the channel cecg1 has a very low amplitude of the R-peaks even after recovering from a severe artifact, channel cecg2 shows larger amplitudes of the R-peaks. Hence, it would be beneficial to use this channel for parameter extraction. Furthermore, the optical channels opt1  and opt3 recover even faster and would thus allow to increase the time in which a reliable heart rate could be estimated. This example clearly shows the opportunities of multichannel unobtrusive monitoring. Our database shall stimulate the research of very robust signal processing algorithms like peak detection, heart rate estimation or sensor fusion, in view of severe and frequent motion artifacts, as these methods are a key aspect for the success of unobtrusive, ubiquitous medical monitoring.

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Content of the dataset

Intially, 145 records with a total of 16.2 hours of measurement data were made available, collected between 2009 and 2013 [2-5] and provided as MATLAB files or in the PhysioNet WFDB file format. Additionally, supplementary functions are provided, which simplify the usage of our database and thus the development and evaluation of new algorithms. The data is available as a MATLAB mat-file or in several files per record in accordance to the PhysioNet WFDB (WaveForm DataBase) file format.

The origin of the data is manifold and currently consists of three application scenarios: measurements of a clinical study [2], measurements while the subject is driving a car [3], [4] and measurements while the subject is lying in bed [5]. Additionally, two records show the maximum measurement quality of our latest system if conditions are optimal. Since the measurements were acquired over a long time period of several years, slightly different (improved) measurement systems were used. In all scenarios, the monitored subjects wore their normal clothes.

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Structure of the dataset

Terms of use

The database is completely free and can be used for any purpose. However, we kindly ask to cite this publication if the database and / or its supplementary functions are used:

T. Wartzek, M. Czaplik, C. Hoog Antink, B. Eilebrecht, R. Walocha and S. Leonhardt: "UnoViS: The MedIT Public Unobtrusive Vital Sign Database", Health Information Science and Systems. 2015;3:2. https://link.springer.com/article/10.1186/s13755-015-0010-1

Structure

The database consists of records which represent one measurement each. That means, a record contains, for example, one measurement of one patient in case of the clinical study, or one driver driving in a specified scenario in case of the driving tests and so on. It should be pointed out that several records may exist for the same subject in the driving or lying in a bed scenario. However, these records are of course labeled with the same unique subject ID but different record IDs. The structure of each record in case of the MATLAB file is given in Table I.

Table 1: Structure of records of the database in MATLAB. The variable n just indicates a varying number greater than one and does not mean that n is always the same in in all fields or records.
Field Datatype Occurrence Content Example
id 1×n char Always Unique identifier of each record UnoViS_auto2012_1
duration 1×1 single Always Duration of record in seconds 500
measScenario 1×n char Always Measurement scenario automotive, city
Subject 1×1 struct Always    
   id 1×n char Always Unique identifier of each subject p1
   clothes 1×n char Optional Clothes worn cotton shirt
     age 1×1 uint8 Optional Age of subject in years 32
     bmi 1×1 single Optional Body mass index (kg m−1) 23.4
     sex 1×1 char Optional Sex m
Channels 1×n struct Always Varying number of n 1×1 structs  
     type 1×n char " Type of channel cecg
     name 1×n char " Name of channel cecg_1
     fs 1×1 single " Sampling rate (Hz) 200
     data n×1 single " Raw data (a.u.)  
     ann 1×n struct Optional Varying number of n 1 x 1 structs  
          type n×1 char " Type of annotation peaks
          source n×1 char " Source/origin of annotation osea
          loc n×1 uint32 " Location(s) of annotation(s) (samples) [25 125 191]
          val Value of the annotation depends on annotation type. Details are given in Table 2.

The presented structure of one record is saved as a struct. Each record consists of several fields such as a unique id, the duration of the measurement, the measurement scenario measScenario, information about the subject and several channels containing the actual measurement data and annotations ann.

 

Table 2: Available annotations.
Dataset Type Meaning Source Value Datatype
All peaks Detected peaks osea OSEA Typecode 1×1 int8
All peaks Detected peaks manual OSEA Typecode 1×1 int8
UnoViS_clin2009 rhythm Atrial fibrillation present? manual 1/0/NaN 1×1 logical
UnoViS_clin2009 extrasys Extrasystole present? manual 1/0/NaN 1×1 logical
UnoViS_clin2009 bbb Bundle branch block? manual 1/0/NaN 1×1 logical
UnoViS_clin2009 hr Heart rate manual [mean, relative difference] 2×1 single
UnoViS_clin2009 pq PQ time manual [mean, relative difference] 2×1 single
UnoViS_clin2009 qrs QRS time manual [mean, relative difference] 2×1 single
UnoViS_clin2009 qt QT time manual [mean, relative difference] 2×1 single

The field ann is an array of structs within each channel. It contains the class (e.g. peaks or rhythm), the subclass which may be event based (e.g. in case of the class peaks) or interval based (e.g. in case of the clinical study the clinicians analyzed an interval of 5 s), the source (e.g. manual by medical experts or automatic by the open source ECG detector OSEA [6]) and the location loc of the annotation in samples. The type of the annotation(s) depends on the annotation class and subclass and is further elucidated in Table II. This table also shows all currently available annotations. All datasets contain detected peaks from OSEA or by a medical expert. In case of the measurements from the clinical study, this dataset contains the following annotations for the cECG as well as for the reference ECG. The diagnosed rhythm and if extrasystoles extrasys or a bundle branch block bbb are present. If the two clinicians could not clearly identify a parameter or if their results differed, it is denoted with NaN or ’-2’. Furthermore, the heart rate and different time durations such as PQ, QRS and QT time are given. Here, the mean value of the two clinicians’ results and the relative difference are given. Again, if one parameter, e.g. the PQ time, could not be clearly estimated, it is denoted with NaN.

Download

The data can be downloaded here:

Dataset Signaltypes # of Records Total Length mat-file wfdb files
UnoViS_clin2009

1 capacitive ECG and

1 reference ECG

92 55 min ZIP ZIP
UnoViS_auto2012

3 capacitive ECGs

1 reference ECG   

31 13.4 h ZIP ZIP
UnoViS_bed2013

3 capacitive ECGs

3 optical pulse

20 1.7 h ZIP ZIP
UnoViS_opti2013

3 capacitive ECGs

3 optical pulse

1 reference ECG

2 6.3 min ZIP ZIP

The supplementary MATLAB functions can be found here:

Matlab Functions / Examples Download  
 for *.mat files ZIP  
 for wfdb files ZIP  

 

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Extensions

1.) A Synthesizer Framework for multimodal cardiorespiratory signals

In [7], our group has published a synthesizer for the generation of multimodal cardiorespiratory signals. Below, a MATLAB demonstration can be downloaded for free. This code was used to generate Figure 14 of the original publication. As the UnoViS database, this code is completely free but we kindly ask you to cite the original publication:

C. Hoog Antink, S. Leonhardt, and M. Walter, “A Synthesizer Framework for Multimodal Cardiorespiratory Signals”, Biomed. Phys. Eng. Express 3 (2017) 035028, https://doi.org/-10.1088/2057-1976/aa76ee.

MATLAB demonstration Download
Synthesizer Demo ZIP

2.) Motion Artifact Quantification and Sensor Fusion for Unobtrusive Health Monitoring

A multisensor setup for unobtrusive vital sign estimation was published by our group in [8]. Here you can download the data of the “Motion Sequence” (UnoViS_motion2017) and the video sequence “Video Sequence” (UnoViS_video2017). The data format is the same as the UnoViS-database. We currently do not provide the data in WFDB format but we can convert it for you if necessary. As with the original database, the data is completely free but we kindly ask you to cite the original publication:

C. Hoog Antink, F. Schulz, S. Leonhardt, and M. Walter, “Motion Artifact Quantification and Sensor Fusion for Unobtrusive Health Monitoring”, Sensors 2018, 18(1), 38; https://doi.org/10.3390/s18010038.

Dataset Signaltypes # of Records Total Length mat-file
UnoViS_motion2017 See [8] 9 81 min ZIP
UnoViS_video2017 See [8] 7 7.1 h ZIP

3.) Signal-Level Fusion with Convolutional Neural Networks for Capacitively Coupled ECG in the Car

In [9], we presented an algorithm for beat-detection in multi-channel capacitively coupled ECG. This algorithm is written in Python and makes use of the “Keras” as well as the “TensorFlow” package (among others). To use this demo, you also need to download the “UnoViS_auto2012” MAT-file you find above. As the UnoViS database, this code is completely free but we kindly ask you to cite the original publication:

C. Hoog Antink, E. Breuer, D. U. Uguz, and S. Leonhardt, “Signal-Level Fusion with Convolutional Neural Networks for Capacitively Coupled ECG in the Car”, in 2018 Computing in Cardiology (CinC 2018);45, doi: https://doi.org/10.22489/CinC.2018.143.

Python Code     Download
CNN_Fusion ZIP

4.) Heart Pacemaker spike can be detected in the capacitive ECG signal

In a clinical study [10], we tested our capacitive ECG car seat on patients with cardiac pacemakers. The multichannel cECG and accompanying reference ECG measurements are provided here in anonymous format for further research purposes. As the UnoViS database, the data and accompanying code is completely free but we kindly ask you to cite the original publication:

D. U. Uguz, R. Dettori, A. Napp, M. Walter, N. Marx, S. Leonhardt, C. Hoog Antink, „Car seats with capacitive ECG electrodes can detect cardiac pacemaker spikes“, Sensors 2020 (20), 6288. doi: https://doi.org/10.3390/s20216288.

Dataset Signaltypes # of Records Total Length mat-file
UnoViS_pacemaker2020 See [10] 97 38 min ZIP

5.) A Portable Multi-Modal Cushion for Continuous Monitoring of a Driver’s Vital Signs

A multi-sensor setup for unobtrusive vital sign estimation was published by our group in [11]. The 4xU sensor data including capacitive ECG, magnetic inductance measurement, PPG and Seismocardiography accompanying the paper can be assessed here. As with the original database, the data is completely free but we kindly ask you to cite the original publication:

O. Linschmann, D.U. Uguz, B. Romanski, I. Baarlink, P. Gunaratne, S. Leonhardt, M. Walter, M. Lüken, „A Portable Multi-Modal Cushion for Continuous Monitoring of a Driver’s Vital Signs“, Sensors 23 (8), 4002, 2023. https://doi.org/10.3390/s23084002.

Dataset Signaltypes # of Records Total Length mat-file
CuMuMoVi See [11] 20 8.1 h ZIP

If you have any questions, please contact us at: unovis-support@hia.rwth-aachen.de

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References

  1. A. L. Goldberger, Amaral, L. A. N., L. Glass, J. M. Hausdorff, P. C. Ivanov, R. G. Mark, J. E. Mietus, G. B. Moody, C.-K. Peng, and H. E. Stanley, “PhysioBank, PhysioToolkit, and PhysioNet: Components of a New Research Resource for Complex Physiologic Signals,” Circulation 101(23):e215–e220, 2000, doi:https://doi.org/10.1161/01.CIR.101.23.e215
  2. M. Czaplik, B. Eilebrecht, R. Walocha, M. Walter, P. Schauerte, S. Leonhardt, and R. Rossaint, “The reliability and accuracy of a noncontact electrocardiograph system for screening purposes,” Anesthesia and Analgesia, 114(2):322–327, 2012, doi: https://doi.org/10.1213/ane.0b013e31823f4182
  3. B. Eilebrecht, T.Wartzek, J. Lem, R. Vogt, and S. Leonhardt, “Capacitive electrocardiogram mea­surement system in the driver seat,” Automobiltechnische Zeitschrift (ATZ), 113(3):232–237, 2011, doi: https://doi.org/10.1365/s38311-011-0034-3
  4. T. Wartzek, B. Eilebrecht, J. Lem, H.-J. Lindner, S. Leonhardt, and M. Walter, “ECG on the Road: Robust and Unobtrusive Estimation of Heart Rate,” IEEE Transactions on Biomedical Engineering, 58(11):3112–3120, 2011, doi: https://doi.org/10.1109/TBME.2011.2163715
  5. T. Wartzek, C. Brüser, T. Schlebusch, C. Brendle, S. Santos, A. Kerekes, K. Gerlach-Hahn, S. Weyer, K. Lunze, C. Hoog-Antink, and S. Leonhardt, “Modeling of Motion Artifacts in Contactless Heart Rate Measurements,” in 2013 Computing in Cardiology (CinC 2013), 22 - 25 Sep 2013.
  6. P. S. Hamilton, "Open Source ECG Analysis Software Documentation," Computers in Cardiology, Memphis, TN, USA, 2002, pp. 101-104, 2002, doi: https://doi.org/10.1109/CIC.2002.1166717
  7. C. Hoog Antink, S. Leonhardt, and M. Walter, “A Synthesizer Framework for Multimodal Car­dio­respiratory Signals”, Biomed. Phys. Eng. Express 3 (2017) 035028, doi: https://doi.org/10.1088/2057-1976/aa76ee.
  8. C. Hoog Antink, F. Schulz, S. Leonhardt, and M. Walter, “Motion Artifact Quantification and Sensor Fusion for Unobtrusive Health Monitoring”, Sensors 2018, 18(1), 38, doi: https://doi.org/10.3390/s18010038
  9. C. Hoog Antink, E. Breuer, D. U. Uguz, and S. Leonhardt, "Signal-Level Fusion with Convolutional Neural Networks for Capacitively Coupled ECG in the Car”, in 2018 Computing in Cardiology (CinC 2018);45, doi: https://doi.org/10.22489/CinC.2018.143
  10. D. U. Uguz, R. Dettori, A. Napp, M. Walter, N. Marx, S. Leonhardt, C. Hoog Antink, "Car seats with capacitive ECG electrodes can detect cardiac pacemaker spikes“, Sensors 2020 (20), 6288, doi: https://doi.org/10.3390/s20216288
  11. O. Linschmann, D.U. Uguz, B. Romanski, I. Baarlink, P. Gunaratne, S. Leonhardt, M. Walter, M. Lüken, „A Portable Multi-Modal Cushion for Continuous Monitoring of a Driver’s Vital Signs“, Sensors 23 (8), 4002, 2023, doi: https://doi.org/10.3390/s23084002.

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