biosignal acquisition tool-kit for advanced research applications

Respiration (PZT) Sensor User ManualRespiration (PZT)
User Manual

ATTENTION
Please read this datasheet before
using your biosignalsplux sensor

The information contained in this document has been carefully checked and were made every effort
to ensure its quality. PLUX reserves the right to make changes and improvements to this manual andproducts referenced at any time without notice.
The word Bluetooth and its logo are trademarks of Bluetooth SIG Inc. and any use of such marks isunder license. Other trademarks are the property of their respective owners.
Please check your systems and sensors after receiving and before using it the first time to confirm if it
contains all the ordered sensors, accessories and other components. Contact our support via e-mail at
support@plux.info if there are any variations from your original order.
For regulatory information, please see the Regulatory Disclaimer at the end of this document.

PLUX – Wireless Biosignals, S.A.
Av. 5 de Outubro, n. 70 – 2.
1050-059 Lisbon, Portugal
plux@plux.info
http://biosignalsplux.com/
v.1.0© 2020 PLUXThis information is provided "as is," and we make no express or implied warranties whatsoever with respect to functionality, operability, use, fitness for aparticular purpose, or infringement of rights. We expressly disclaim any liability whatsoever for any direct, indirect, consequential, incidental or special
damages, including, without limitation, lost revenues, lost profits, losses resulting from business interruption or loss of data, regardless of the form of action orlegal theory under which the liability may be asserted, even if advised of the possibility of such damages.

Respiration (PZT)
User Manual

TABLE OF CONTENTS
1.

General Information ............................................................................................................. 4
1.1. General Description ........................................................................................................... 4
1.2. Typical Unfiltered Sensor Output........................................................................................ 4
1.3. Sensor Specifications ......................................................................................................... 5
1.4. Features ............................................................................................................................ 5
1.5. Applications....................................................................................................................... 5
1.6. Transfer Function (Conversion Formula) ............................................................................. 5
1.7. Physical Characteristics ...................................................................................................... 6

2. Application Notes ..................................................................................................................... 7
3. Using the Respiration (PZT) Sensor with biosignalsplux & OpenSignals ..................................... 10
3.1. Connecting the sensor to biosignalsplux Systems .............................................................. 10
3.1.1. biosignalsplux 4-Channel Hubs ........................................................................................... 10
3.1.2. biosignalsplux 8-Channel Hubs ........................................................................................... 10
3.1.3. biosignalsplux Solo & Single-Channel openBAN Devices ................................................... 11
3.2. Configuring the Sensor in OpenSignals.............................................................................. 11
3.2.1. OpenSignals (r)evolution (Windows, macOS, Linux) .......................................................... 11
4. Scientific Publications Using the PZT Sensor ............................................................................ 14
5. Safety & Maintenance ............................................................................................................ 15
5.1. Safety Instructions ........................................................................................................... 15
5.2. Transportation and Storage.............................................................................................. 16
5.3. Cleaning .......................................................................................................................... 16
6. Ordering Guides, Regulatory & Legal Information .................................................................... 17
6.1. Ordering Guide ................................................................................................................ 176.2. Guarantee of Quality & Warranty..................................................................................... 176.3. Warranty Voidance .......................................................................................................... 176.4. Contact & Support ........................................................................................................... 18
6.5. Regulatory Disclaimer ...................................................................................................... 18

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1. General Information
1.1. General Description
The biosignalsplux piezoelectric Respiration (PZT) sensor is an entry-level and affordable solution forbasic respiration data acquisition. This sensor consists of a wearable chest-belt with an integrated
localized sensing element that measures displacement variations caused by the volume changes of thethorax or abdomen during respiratory cycles (inhaling/exhaling).
The elastic chest-belt can be adjusted in length to be applicable on different anatomies (e.g. male
and/or female), body locations (e.g. thorax and/or abdomen), and thorax/abdomen circumferences.
Typical applications of this sensor include respiration monitoring to determine respiration cycles, rates,
relative amplitudes, and other features.
Together with the Respiration Analysis add-on for our OpenSignals software, one can easily record andextract meaningful temporal and spectral signal parameters for further analysis of the acquired sensor
data.

Figure 1: biosignalsplux PZT sensor (standard version)

1.2. Typical Unfiltered Sensor Output
Figure 2 shows a typical unfiltered PZT sensor output acquired while at rest and during a deep breath.
The raw digital sensor values received from the biosignalsplux device ranged between 0 and 2n-1(n=sampling resolution) and can be converted into the original unit of measurement of this sensor (V)using the transfer function found in section Transfer Function (Conversion Formula).

Figure 2: Typical unfiltered sensor output (at rest and during a deep breath)

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1.3. Sensor Specifications> Gain:> Bandwidth:> Input Impedance:

10.059-1 Hz-> Range:> Consumption:> CMRR:± 1.50 V
35 uA≥ 106 dB [TYP: 130 dB]

1.4. Features> Piezoelectric film technology> Differential measurement> Adjustable elastic chest strap> High signal-to-noise ratio> Medical-grade raw data output> Unobtrusive & lightweight sensor> Pre-conditioned analog output> Displacement measurement> Ready-to-use form factor> Raw signal output

1.5. Applications> Thoracic or abdominal respiration analysis> Sleep studies> Biofeedback> Life sciences studies> Respiratory cycles measurement> Biomedical research> Psychophysiology> Biomedical device prototyping

1.6. Transfer Function (Conversion Formula)
The analog sensor signals acquired with biosignalsplux devices are converted into digital values ranged
between 0 and 2n-1 (n=sampling resolution, usually 8-bit or 16-bit) and streamed in the raw digitalformat.
In most applications, the original physical unit of the acquired PZT signal is preferred or required. The
raw digital sensor samples can be converted back into volt (V) using the following formula:
𝐴𝐷𝐶 1( 𝑛 − ) × 𝑉𝐶𝐶
2-1 2𝑃𝑍𝑇(𝑉) =𝐺𝑃𝑍𝑇(1)Valid sensor range: [-1.5V, 1.5V]
with:

𝑃𝑍𝑇(𝑉)
𝐴𝐷𝐶
𝑛
𝑉𝐶𝐶
𝐺𝑃𝑍𝑇

PZT signalError! Reference source not found. in V
Value samples from the sensor/channel (digital value)
Sampling resolution (default: 16-bit resolution (n=16), although 12-bit and 8bit may also be found)
Operating voltage (3V when used with biosignalsplux)
Sensor gain (1 | Not amplified signal)

The previous absolute value in V can also be converted to a relative measure ([-50, 50] %), intended
to present (through a percentual value) the degree of extension/compression of the chest band during
inhalation/exhalation.
Achieving this format is very simple, and essentially it will only be necessary to replace the 𝑉𝐶𝐶 value(in V) by the percentual upper threshold (100%):
𝐴𝐷𝐶 1(2𝑛 - 1 − 2) × 100%
𝑃𝑍𝑇(%) =𝐺𝑃𝑍𝑇
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1.7. Physical Characteristics> W1 x L1 x H:
> W3:
> L2:
> A2:
> S:
>Available sleeve colors:

1.6cm x 2.2cm x 0.5cm> W2:
1.0±0.1cm
0.4±0.1cm> W4:
0.2±0.1cm
2.6±0.1cm> A1:
105.0±0.5cm
7.0±0.1cm> A3:
15.3±0.1cm
0.3±0.1cm
White, Black, Blue, Green, Red, Yellow, Grey, and Brown

Figure 3: Physical characteristics of the standard Piezoelectric (PZT) sensor.

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2. Application Notes
For a proper data acquisition of the respiratory signal using the PZT sensor, it will be important tounderstand the influence of sensor placement on the respiratory signal.
Rib cage diameter is not uniform, with mediolateral dimensions a little bit higher than anteriorposterior diameter [1], [2]. Due to this morphology, during respiration, the rib cage
expansion/contraction varies accordingly to the chest point under analysis. Taking into considerationthat PLUX’s PZT sensor measures deformations, it means that respiration signal morphology will bedependent on sensor placement.
As concluded by some studies, during respiration, the anteroposterior displacement is generally higher
than the transversal one [3], i.e., during respiration change of rib cage diameter is less accentuatedlaterally, so, at a first glance we can think that when PZT sensor is placed on frontal region it will always
register greater peak-to-peak amplitudes during the breathing process (because greater displacements
means bigger deformation applied to PZT sensor).
PZT sensor measures deformation, so, we should not restrict our analysis to unidimensional measures.
Another study went a little bit deeper on this question concluding that during normal breathing
abdominal 3-dimensional motion is more accentuated on abdominal points when compared tothoracic markers, but lateral 3-dimensional motion on lateral points were not always smaller thanfrontal ones [4].
For example, thoracic lateral points revealed a bigger 3D motion, when compared with frontal points,
logic that is reversed for abdominal points.
In order to test the validity of PZT sensor measurements, data was collected using different sensor
positions:a) Nipple line;
i. Frontal;
ii. Lateral.
b) Between 8th and 10th Rib;i. Frontal;
ii. Lateral.

Figure 4: Schematically representation of PZT sensor position.

So, based on past researches, it can be expected that the previous four sensor positions should present
the following qualitative results (peak-to-peak amplitude):

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Table 1 - Expected Results for PZT Sensor

Major
Location

Location

Orientation

3D Motion(expected)

Thorax

Nipple Line

FrontalIntensity 1

Thorax

Nipple Line

LateralIntensity 2

Abdomen

8th to 10th Rib

LateralIntensity 3

Abdomen

8th to 10th Rib

FrontalIntensity 4

Peak-to-Peak
Amplitude (expected)

Through a simple experimental protocol, the obtained results are in accordance with the theoretical
expectations, as demonstrated on the following table, which synthetises the estimations made using
OpenSignals Respiration Analysis add-on.
Table 2 – Experimental Results for PZT Sensor

Major
Location

Location

Orientation

3D Motion(expected)

Peak-to-Peak
Amplitude(Raw 16 bits Data)

Thorax

Nipple Line

FrontalIntensity 1

7204

Thorax

Nipple Line

LateralIntensity 2

16888

Abdomen

8th to 10th Rib

LateralIntensity 3

14068

Abdomen

8th to 10th Rib

FrontalIntensity 420163

In order to these differences can be graphically seen, in the next two figures it is compared the acquired
signals from two extreme situations (Nipple Line Frontal vs 8th to 10th Rib Frontal).

Figure 5: Graphical differences between the two extreme configurations.

As can be seen the 8th to 10th Ribs configuration is smoother and presents a bigger amplitude, which
may be more practical for the researcher and even during the processing stage of respiratory signals
while detecting specific events, taking into account that sometimes the rugosity of the signal brings
additional processing challenges.

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A metric that can be used to understand which is the most adequate configuration, for acquiring datawith PZT Sensor, is related with the effectiveness of breath cycles count by OpenSignals Respiration
Analysis add-on, i.e., configurations that ensure a correct breath cycles count are preferable in orderto get access to more precise processing results.
Table 3 – Real vs Detected breath cycles count

Major
Location

Location

Orientation

Real Number ofComplete Breaths

Automatic Number ofDetected Breaths

Thorax

Nipple Line

Frontal5

6Thorax

Nipple Line

Lateral77

Abdomen

8th to 10th Rib

Lateral67

Abdomen

8th to 10th Rib

Frontal7

7

There are no significative differences on the performance of OpenSignals Respiration Analysis add-on
for the different sensor positions, being the previous test very useful to demonstrate the reliability of
PLUX processing algorithm.

Bibliographic References[1]

F. Bellemare, A. Jeanneret, and J. Couture, “Sex differences in thoracic dimensions andconfiguration,” Am. J. Respir. Crit. Care Med., vol. 168, no. 3, pp. 305–312, 2003.

[2]

A. Joshua and Sa. Joshua, “Variations in Dimensions and Shape of Thoracic Cage With Aging: an
Anatomical Review,” Anat. J. Africa, vol. 3, no. 2, pp. 346–355, 2014.

[3]

J. C. Leong, W. W. Lu, K. D. Luk, and E. M. Karlberg, “Kinematics of the chest cage and spine
during breathing in healthy individuals and in patients with adolescent idiopathic scoliosis.,”Spine (Phila. Pa. 1976)., vol. 24, no. 13, pp. 1310–1315, Jul. 1999.

[4]

H. Kaneko and J. Horie, “Breathing Movements of the Chest and Abdominal Wall in Healthy
Subjects,” Respir. Care, vol. 57, no. 9, pp. 1442–1451, 2012.

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3. Using the Respiration (PZT) Sensor with biosignalsplux &OpenSignals
3.1. Connecting the sensor to biosignalsplux Systems
3.1.1. biosignalsplux 4-Channel Hubs
The biosignalsplux PZT sensor is compatible with all 4 analog input channels of the 4-channel
biosignalsplux hub, but incompatible with the reference/ground port. Connect the sensor to an analog
input to use it with this device.

Figure 6: PZT compatible biosignalsplux channels (green checkmarks).

3.1.2. biosignalsplux 8-Channel Hubs
The biosignalsplux PZT sensor is compatible with all 8 analog input channels of the 8-channel
biosignalsplux hub, but incompatible with the reference/ground and digital I/O ports. Connect thesensor to an analog input to use it with this device.

Figure 7: PZT compatible biosignalsplux channels (green checkmarks).

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3.1.3. biosignalsplux Solo & Single-Channel openBAN Devices
The biosignalsplux PZT sensor is compatible with the analog input channel of the biosignalsplux Solo
(openBAN) device. Connect the sensor to the analog input channel to use it with this device.

Figure 8: Connect the PZT to the analog input channel of the biosignalsplux Solo (openBAN).

3.2. Configuring the Sensor in OpenSignals
3.2.1. OpenSignals (r)evolution (Windows, macOS, Linux)

Note
Download OpenSignals (r)evolution here: https://biosignalsplux.com/index.php/software
Open the OpenSignals (r)evolution device manager to access and configure your biosignalsplux
device.

Figure 9: Access the OpenSignals (r)evolution device manager.

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Select the device you intend to use for acquisition by clicking on ENABLE button on the device panel in
the OpenSignals device manager. The device is activated for acquisition if the ENABLE button is blue.

Figure 10: Enabling the device for acquisition.

Click on the biosignalsplux logo to access the available settings. Select the channel your sensor isconnected to and select the RESP from the dropdown menu highlighted in the next screenshot.

Figure 11: Set the channel type of the channel you have your PZT sensor connected to, to RESP.

Activate the channel for acquisition by clicking on the circle next to the channel type (must be blue). If
not done before, follow the instruction available in section 2 Application Notes to learn how to apply
the sensors and 3.1 Connecting the sensor to biosignalsplux Systems to learn how to connect yourdevice to your biosignalsplux device. Click on the record button in the OpenSignals main interface
whenever you’re ready for your acquisition.

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Figure 12: Start the acquisition whenever you’re ready.

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4. Scientific Publications Using the PZT Sensor
The following scientific is only a small selection extracted from the list of available publications usingbiosignalsplux. Please visit the following website to access the entire up-to-date list:
biosignalsplux Publications
List of Publications

Publications
J. E. Muñoz, A. Gonçalves, T. Vieira, D. Cró, Y. Chisik, S. Bermúdez i Badia, "Space connection-a
multiplayer collaborative biofeedback game to promote empathy in teenagers: A feasibility study" in
Proc. of 3rd International Conference on Physiological Computing Systems, pp. 88-97, 2016
M. Cheetham, C. Cepeda, H. Gamboa, "Automated Detection of Mind Wandering: A Mobile
Application", in Proc. of the 9th International Joint Conference on Biomedical Engineering Systems andTechnologies (BIOSTEC), vol. 4: BIOSIGNALS, pp. 198-205, 2016
Y. Xu, I. Hübener, A. Seipp, S. Ohly, K. David, "From the lab to the real-world: An investigation on theinfluence of human movement on Emotion Recognition using physiological signals", in Proc. of the2017 IEEE International Conference on Pervasiva Computing and Communications Workshops (PerCom
Workshops), pp. 345-350, 2017
E. Lux, M. Adam, V. Dorner, S. Helming, M. Knierim, C. Weinhardt, "Live Biofeedback as a User Interface
Design Element: A Review of the Literature", in Communications of the Association for Information
Systems, vol. 43, no. 18, pp. 257-296, 2018
A. Kamenz, V. Bibaeva, A. Bernin, S. Ghose, K. von Luck, F. Vogt, L. Müller, "Classification of
Physiological Data in Affective Exergames", in Proc. of the IEEE Symposium Series on Computational
Intelligence (SSCI), pp. 2076-2081, 2018
J. Heinisch, I. Hübener, K. David, "The Impact of Physical Activities on the Physiological Response to
Emotions", in Proc. of the International Conference on Pervasive Computing and Communications
Workshops (PerCom Workshops), pp. 824-829, 2018
M. Mateu-Mateus, F. Guede-Fernandéz, V. Ferrer-Mileo, M. García-González, J. Ramos-Castro, M.
Fernández-Chimeno, "Comparison of video-based methods for respiration rhythm measurement", in
Biomedical Signal Processing and Control, vol. 51, pp. 138-147, 201914 of 19

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5. Safety & Maintenance5.1. Safety Instructions
Please read the following safety instructions before using your biosignalsplux system with the PZT
sensor to prevent any damages or problems with the user, test persons and/or biosignalsplux devices.
Violations of these instructions can lead to inferior signal quality and/or damages to the biosignalsplux
system and user.
!

The user should always keep the device and its accessories dry.

!

The user must turn off the biosignalsplux device and contact Technical Support if the systemor accessories reach uncomfortable temperatures.

!

The user should not use the biosignalsplux device in noisy environments (environments withmicrowaves and other similar equipment). Doing so will lead to noise increase in the acquired
signals and Bluetooth connectivity issues.

!

The user must not use the device near the fire or in potentially explosive atmospheres, such asatmospheres with flammable gas.

!

The user should only use the detection surfaces or other approved accessories purchased fromPLUX or by a PLUX agent.

!

The user should inspect the sensors on a regular basis to ensure that they remain in goodworking order.

!

The user should stop using the biosignalsplux device if experience any kind of discomfort orskin irritation.

!

Do not use the system on persons with allergies to silver.

!

The user should dispose detection surfaces after using the biosignalsplux device. Detection
surfaces are single-user and disposable. Reusable electrodes should be reused by the sameuser. Do not use reusable electrodes on several users.

!

The user must not place the device in the microwave.

!

The user must not insert objects into the holes of the device.

!

The user should not open the biosignalsplux device or its accessories. The repair of the sameshould be only done by properly authorized PLUX personnel.

!

The user should make sure the cables do not obstruct the passage of people.

!

The user should use the sensor cables with extreme caution to avoid risk of strangulation.

!

The user should keep a safe distance between the biosignalsplux device and other devices toensure their proper functioning.

!

The user should only send the device to repair to qualified PLUX personnel.

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The user should not immerse the sensors or the biosignalsplux device, nor clean with liquid orabrasives.

!

The user should handle the biosignalsplux device with caution and not expose the device oraccessories to high accelerations and vibrations.

!

biosignalsplux devices should not be used in patients with implanted electronic devices of any
kind, including pace-makers, electronic infusion pumps, stimulators, defibrillators or similar.

!

Do not apply electrodes over damaged or irritated skin.

!

Do not use your device while charging its internal battery.

5.2. Transportation and Storage
Please follow these recommendations to ensure safe transportation and storage of yourbiosignalsplux equipment and sensors to prevent any damaging of your system.
The biosignalsplux equipment and sensors should be stored in the original box in a dry place whenthose are not being used.
•••

Relative humidity: up to 95% with no condensation
Ambient temperature: 10°C to 30°C
Atmospheric pressure between 500hPa and 1060hPa

Whenever the equipment needs to be transported, it should be placed in the original box, since thiswas designed and tested to ensure the equipment and accessories are securely stored.
Take care while handling the transportation of the system and avoid dropping it, since the device is
not shock-proof and should not be placed under stress or sudden acceleration.

5.3. Cleaning
Please follow these cleaning instructions to prevent any damage of the system or the user because of
conducting cleaning methods that may cause any damage.
•The biosignalsplux and sensors should be visually checked before each use and cleaning
process to ensure that no mechanical damage occurred.

•

The biosignalsplux equipment and sensors (including the cables) should be cleaned with aslightly damp cloth or suitable absorbent paper, ensuring no liquid enters the equipment ofsensors. Do not use detergent or any type of cleaning liquid as these may damage yourequipment and/or sensor.

•

Do not clean or re-use detection surfaces (electrodes). They are only suitable for single use
and should be disposed of after usage except indicated otherwise.

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6. Ordering Guides, Regulatory & Legal Information
6.1. Ordering Guide
Please follow the following ordering guide when submitting orders of PZT sensors to orders@plux.info.
If no specification is provided, the standard version of the sensor will be delivered.
PZT Sensor
SKU Reference
PLUX CodeUPC
SENSPRO-PZT1
820201208
641945696271
Description
Piezoelectric respiration sensor for respiratory analysis in a wide range of applications. It has alocalized sensing element that measures displacement variations induced by inhaling or exhaling
and can be adjusted in length.
Electrodes & Accessories
For a full list of available and compatible electrodes, please visit the biosignalsplux store.

6.2. Guarantee of Quality & Warranty
biosignalsplux sensors have three months quality guarantee from the date of purchase. PLUX
guarantees that the system, sensors and accessories will be free from material or manufacturing
defects for the mentioned time periods following date of purchase.
If PLUX receives notification of any such defects within the guarantee period, it will repair or substitutewith the same unit/model, any products with proven defects at no cost to the client. During the repair
period PLUX promises to provide a temporary replacement under the same specification. Repairs will
be carried out at PLUX’s premises after the equipment has been received.

6.3. Warranty Voidance
Usage of the device that is not in accordance with the handling instructions indicated in the manual,or use with accessories other than those manufactured by PLUX will invalidate the warranty of yourdevices.
Be careful when connecting your biosignalsplux devices, sensors and/or accessories to any third party
device including the usage of the 3rd party connection components that are available forbiosignalsplux systems as the usage of these components will void the electrical warranty of yourbiosignalsplux device and sensors and, if not indicated otherwise, the warranty of the 3rd party
system you’re connecting to the device. Check the electrical specifications of both systems you wantto connect to prevent any damage of the user(s) or the systems.
In the case of warranty voidance, the same applies that we expressly disclaim any liability whatsoever
for any direct, indirect, consequential, incidental or special damages, including, without limitation, lost
revenues, lost profits, losses resulting from business interruption or loss of data, regardless of the formof action or legal theory under which the liability may be asserted, even if advised of the possibility ofsuch damages.

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6.4. Contact & Support
Contact us if you are experiencing any problems that cannot be solved with the information given in
the biosignalsplux documentation.
Please send us an e-mail with precise information about the error occurrence, device configuration,
and, if possible, screenshots of the problem to support@plux.info.

6.5. Regulatory Disclaimer
biosignalsplux products are intended for use in life science education and research applications; they
are not medical devices nor are they intended for medical diagnosis, cure, mitigation, treatment or
prevention of disease. We expressly disclaim any liability whatsoever for any direct, indirect,
consequential, incidental or special damages, including, without limitation, lost revenues, lost profits,losses resulting from business interruption or loss of data, regardless of the form of action or legal
theory under which the liability may be asserted, even if advised of the possibility of such damages.

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PLUX Wireless Biosignals S.A.
email: plux@plux.info
web: http://www.plux.info
Headquarters
Zona Industrial das Corredouras, Lt. 14 – 1°
2630-369 Arruda dos Vinhos
Portugaltel.: +351 263 978 572
fax: +351 263 978 902
Lisbon Office
Av. 5 de Outubro, n° 70 – 2°1050-059 Lisboa
Portugaltel.: +351 211 956 542
fax: +351 211 956 546

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