IEC 62830-4:2019

Semiconductor devices - Semiconductor devices for energy harvesting and generation - Part 4: Test and evaluation methods for flexible piezoelectric energy harvesting devices

IEC 62830-4:2019 describes terms, definitions, symbols, configurations, and test methods that can be used to evaluate and determine the performance characteristics of flexible piezoelectric energy harvesting devices for practical use. This document is applicable to energy harvesting devices for consumers, general industries, wearable electronics, military, and biomedical applications without any limitations of device technology and size.

Dispositifs à semiconducteurs - Dispositifs à semiconducteurs pour récupération et production d'énergie - Partie 4: Méthodes d’essai et d’appréciation pour les dispositifs de récupération d’énergie piézoélectrique souples

L’IEC 62830-4:2019 décrit les termes, définitions, symboles, configurations et les méthodes d’essai pouvant être utilisés pour apprécier et déterminer les caractéristiques de performance des dispositifs de récupération d’énergie piézoélectrique souples dans le contexte d’une utilisation pratique. Le présent document s’applique aux dispositifs de récupération d’énergie destinés au grand public, aux industries générales, aux appareils électroniques portatifs et aux applications militaires et biomédicales, sans restriction concernant la technologie et la taille des dispositifs.

General Information

• Status: Published
• Publication Date: 26-Feb-2019
• ICS: 31.080.99 - Other semiconductor devices
• Technical Committee: TC 47 - Semiconductor devices
• Drafting Committee: WG 7 - TC 47/WG 7
• Current Stage: PPUB - Publication issued
• Start Date: 27-Feb-2019
• Completion Date: 29-Mar-2019

Standards Content (Sample)

IEC 62830-4 ®
Edition 1.0 2019-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Semiconductor devices – Semiconductor devices for energy harvesting and
generation –
Part 4: Test and evaluation methods for flexible piezoelectric energy harvesting
devices
Dispositifs à semiconducteurs – Dispositifs à semiconducteurs pour
récupération et production d’énergie –
Partie 4: Méthodes d’essai et d’appréciation pour les dispositifs de récupération
d’énergie piézoélectrique souples

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IEC 62830-4 ®
Edition 1.0 2019-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Semiconductor devices – Semiconductor devices for energy harvesting and

generation –
Part 4: Test and evaluation methods for flexible piezoelectric energy harvesting

devices
Dispositifs à semiconducteurs – Dispositifs à semiconducteurs pour

récupération et production d’énergie –

Partie 4: Méthodes d’essai et d’appréciation pour les dispositifs de récupération

d’énergie piézoélectrique souples

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ISBN 978-2-8322-6609-0
ICS 31.080.99
– 2 – IEC 62830-4:2019 © IEC 2019
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
3.1 General terms . 6
3.2 Piezoelectric transducer . 8
3.3 Characteristic parameters . 8
4 Essential ratings and characteristic parameters . 10
4.1 Limiting values and operating conditions . 10
4.2 Additional information . 11
5 Test method . 11
5.1 General . 11
5.2 Electrical characteristics . 12
5.2.1 Test procedure . 12
5.2.2 Capacitance . 13
5.2.3 Open circuit voltage . 14
5.2.4 Short circuit current . 14
5.2.5 Open circuit voltage with various induced strains . 15
5.2.6 Short circuit current with various induced strains . 15
5.2.7 Open circuit voltage with various induced frequencies . 16
5.2.8 Short circuit current with various induced frequencies. 17
5.2.9 Output load voltage . 18
5.2.10 Output current . 19
5.2.11 Output power . 19
5.2.12 Optimal load impedance . 20
5.2.13 Maximum output power . 20
5.2.14 Test procedure . 20
5.2.15 Temperature range . 21
5.2.16 Relative humidity range . 22
5.2.17 Input bending motion range . 22
5.2.18 Input stretching motion range . 22
5.2.19 Input twisting motion range . 22
Annex A (informative) Piezoelectric modes . 23
A.1 General . 23
A.2 d mode. 23
A.3 d mode. 23
Annex B (informative) Classification of flexible piezoelectric energy harvesters . 25
B.1 General . 25
B.2 Piezoelectric thin film with top and bottom electrodes (d mode). 25
B.3 Piezoelectric thin film with comb structured electrodes (d mode) . 25
B.4 Piezoelectric nano wire with top and bottom electrodes . 25
B.5 Flexible piezoelectric material with top and bottom electrodes . 25
Annex C (informative) Input motions . 27
C.1 Classification of strain motions. 27
C.2 Example of test method . 27

Annex D (informative) Electromechanical coupling . 29
D.1 Compliance and coupling coefficient relation. 29
D.2 Young’s modulus and coupling coefficient relation . 29
Bibliography . 30

Figure 1 – Flexible energy harvester using a flexible substrate with a piezoelectric film . 7
Figure 2 – Equivalent circuit of flexible piezoelectric energy harvester . 9
Figure 3 – Measurement procedure of flexible piezoelectric energy harvesters . 12
Figure 4 – Test setup for the electrical characteristics of a flexible piezoelectric energy
harvester . 13
Figure 5 – Open circuit voltage of a flexible piezoelectric energy harvester . 14
Figure 6 – Short circuit current of a flexible piezoelectric energy harvester . 14
Figure 7 – Open circuit voltage of the flexible piezoelectric energy harvester with
various induced strains . 15
Figure 8 – Short circuit current of the flexible piezoelectric energy harvester with

various induced strains . 16
Figure 9 – Open circuit voltage of the flexible piezoelectric energy harvester with
various induced frequencies . 17
Figure 10 – Short circuit current of the flexible piezoelectric energy harvester with
various induced frequencies . 18
Figure 11 – Output load voltages of flexible piezoelectric energy harvester at various

external loads . 19
Figure 12 – Output current of the flexible piezoelectric energy harvester at various
output voltages . 19
Figure 13 – Output power of the flexible piezoelectric energy harvester at various
external loads . 20
Figure 14 – Output power and voltage of the flexible piezoelectric energy harvester at

various input bending, stretching, or twisting motions . 20
Figure 15 – Block diagram of a test setup for evaluating the reliability of the flexible
piezoelectric energy harvester . 21
Figure A.1 – Piezoelectric mode of the bending beam based energy harvester . 24
Figure B.1 – Classification of flexible piezoelectric energy harvesters . 26
Figure C.1 – Classification of strain motions applied for flexible piezoelectric energy
harvesters . 27
Figure C.2 – The output current measurement for different types of stretching . 28

Table 1 – Specification parameters for flexible piezoelectric energy harvesters . 10

– 4 – IEC 62830-4:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SEMICONDUCTOR DEVICES –
SEMICONDUCTOR DEVICES FOR
ENERGY HARVESTING AND GENERATION –

Part 4: Test and evaluation methods for
flexible piezoelectric energy harvesting devices

FOREWORD
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International Standard IEC 62830-4 has been prepared by IEC technical committee 47:
Semiconductor devices.
The text of this International Standard is based on the following documents:
FDIS Report on voting
47/2530/FDIS 47/2551/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts in the IEC 62830 series, published under the general title Semiconductor
devices – Semiconductor devices for energy harvesting and generation, can be found on the
IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – IEC 62830-4:2019 © IEC 2019
SEMICONDUCTOR DEVICES –
SEMICONDUCTOR DEVICES FOR
ENERGY HARVESTING AND GENERATION –

Part 4: Test and evaluation methods for
flexible piezoelectric energy harvesting devices

1 Scope
This part of IEC 62830 describes terms, definitions, symbols, configurations, and test
methods that can be used to evaluate and determine the performance characteristics of
flexible piezoelectric energy harvesting devices for practical use. This document is applicable
to energy harvesting devices for consumers, general industries, wearable electronics, military,
and biomedical applications without any limitations of device technology and size.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60749-5, Semiconductor devices – Mechanical and climatic test methods – Part 5:
Steady-state temperature humidity bias life test
IEC 60749-12, Semiconductor devices – Mechanical and climatic test methods – Part 12:
Vibration, variable frequency
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 General terms
3.1.1
flexible
capability of being bent or flexed
3.1.2
flexible energy harvester
energy transducer that transforms bending, stretching, or twisting energy into electric energy
Note 1 to entry: A flexible energy harvester which converts applied stress by bending, stretching or twisting to
electricity using a piezoelectric transducer is comprised of a spring and a piezoelectric transducer as shown in
Figure 1. The piezoelectric transducer contains two electrodes and a piezoelectric film or nano wires. The induced
external stress introduces the bending, stretching or twisting motion to the flexible substrate as shown in Annex C.
The flexible substrate is bent and the bending of the spring introduces tension and compression of the piezoelectric
film. The top and bottom electrodes of the piezoelectric film harvest the generated charges resulting from the
piezoelectric effect.
1(a) Unimorph type
1(b) Bimorph type
Key
Configuration of energy harvester Components to operate energy
harvester
1 Piezoelectric film which is R External load
the body layer of the
piezoelectric transducer for
energy harvesting
2 Spring, to couple the L+, L- Outputs of energy
induced bending, stretching harvester
or twisting to the flexible
substrate by suspending it
Figure 1 – Flexible energy harvester using a flexible substrate with a piezoelectric film
Note 2 to entry: The flexible piezoelectric energy harvester can be classified into four different types as shown in
Annex B.
3.1.3
unimorph cantilever
cantilever that consists of one piezoelectric layer
Note 1 to entry: A unimorph cantilever consists of two layers where the piezoelectric layer is attached with the
non-piezoelectric layer that works as a spring to introduce external stress to the piezoelectric layer.
3.1.4
bimorph cantilever
cantilever that consists of two piezoelectric layers
Note 1 to entry: In a bimorph cantilever, a non-piezoelectric layer is placed between two piezoelectric layers.
3.1.5
flexible substrate
substrate that is made from flexible materials, such as polyimide and PDMS
3.1.6
spring
elastic object to store mechanical energy with spring constant, k
sp
[SOURCE: IEC 62830-1:2017, 3.1.5]

– 8 – IEC 62830-4:2019 © IEC 2019
3.2 Piezoelectric transducer
3.2.1
piezoelectric transducer
energy converter to generate electricity from mechanical energy by means of piezoelectric
effect
[SOURCE: IEC 62830-1: 2017, 3.2.1]
3.2.2
piezoelectric effect
effect by which a mechanical deformation of piezoelectric material produces a proportional
change in the electric polarization of that material
3.2.3
piezoelectric constant
d
quantifying value of the polarization in the piezoelectric material on application of a stress
3.2.4
electromechanical coupling coefficient
k
value to describe the conversion rate of electrical energy to mechanical form or vice versa
Note 1 to entry: The coefficient is a combination of elastic, dielectric and piezoelectric constants which appears
naturally in the expression of the piezoelectric transducer.
d
k= (1)
1/2
(sε)
where
d is the piezoelectric charge constant;
s is the elastic compliance (inverse of Young's modulus) at constant electric field;
ε is the permittivity of the piezoelectric material at constant stress.
Note 2 to entry: Annexes A and D show additional information for the piezoelectric constant and
electromechanical coupling.
3.2.5
capacitance
C
p
capacitance between the two electrodes of the piezoelectric transducer
3.3 Characteristic parameters
3.3.1
equivalent circuit
electrical circuit which has the same output voltage
from induced bending, stretching, or twisting motion as the piezoelectric flexible energy
harvester in the immediate neighborhood of a resonance
Note 1 to entry: A flexible piezoelectric energy harvester can be divided into current source and capacitance parts
as shown in Figure 2. The equivalent circuit is comprised of parallel connected C , of R, and of transformer (I(t)),
p
where C and R represent the capacitance between the two electrodes of the piezoelectric transducer and external
p
load.
Key
I(t) current source of piezoelectric
transducer
C capacitance of piezoelectric transducer
p
R external load
Figure 2 – Equivalent circuit of flexible piezoelectric energy harvester
3.3.2
open circuit voltage
V
electrical potential difference relative to a reference node of energy harvester when there is
no external load connected to the terminals of the energy harvester
3.3.3
short circuit current
I
current through the external load connected to the terminal of an energy harvester
[SOURCE: IEC 62830-1:2017, 3.3.6, modified – the term "ouput current" has been replaced
by "short circuit current".]
3.3.4
output power
P
electrical power transferred to the external load connected to the terminal of an energy
harvester
[SOURCE: IEC 62830-1:2017, 3.3.5]
3.3.5
power density
electrical power per unit volume (including seismic mass and clamper) transferred to the
external load connected to the terminals of the energy harvester
3.3.6
optimal load
R
opt
specified value of the external load for transferring the largest electrical energy from the
energy harvester
[SOURCE: IEC 62830-1: 2017, 3.3.7]

– 10 – IEC 62830-4:2019 © IEC 2019
3.3.7
temperature range
range of temperature as measured on the enclosure over which the energy harvester will not
sustain permanent damage though not necessarily functioning within the specified tolerances
[SOURCE: IEC 62830-1: 2017, 3.3.9]
3.3.8
humidity range
range of humidity as measured in the enclosure over which the energy harvester will not
sustain permanent damage though not necessarily functioning within the specified tolerances
3.3.9
input stress
range of stress induced by bending motion, stretching motion, and twisting motion to the
energy harvester as measured on the enclosure over which the energy harvester will not
sustain permanent damage under long term operation though not necessarily functioning
within the specified tolerances
3.3.10
mean-time-to-failure
length of time the energy harvester is expected to last in operation without failure or
disruption
4 Essential ratings and characteristic parameters
4.1 Limiting values and operating conditions
Specification and characteristic parameters should be listed as shown in Table 1. The
manufacturer shall clearly announce the operating conditions and their limitation for energy
harvesting. The limiting value is the maximum induced bending, stretching or twisting motion
to ensure the long term operation of the flexible energy harvester for power generation
without any damage.
Table 1 – Specification parameters for flexible piezoelectric energy harvesters
Measuring
Parameters Symbols Min. Max. Unit
conditions
Insert name of
characteristic
parameters
The information provided in Table 1 is the following:
– Parameters: name of the characteristic parameters;
– Symbols: symbol of the parameters;
– Min.: minimum value of the parameters;
– Max.: maximum value of the parameters;
– Unit: unit of the parameters;
– Measuring conditions: specified conditions for evaluation.

4.2 Additional information
Some additional information should be given such as equivalent circuits (e.g. resonant
frequency, internal impedance, frequency response, output voltage and power, etc.), handling
precautions, physical information (e.g. outline dimension, terminals, etc.), accessories,
installation guide, package information, PCB interface and mounting information, and other
information.
5 Test method
5.1 General
Basically, the general test procedures for a flexible energy harvester are performed as shown
in Figure 3. After the flexible piezoelectric energy harvester is being mounted on a test fixture,
it is measured by using voltage, current, and LCR meters. To measure and characterize these
devices accurately, the ultra-high-impedance meters should be used.
After calibration of the measuring equipment, connect the test cable with the output terminals
of the flexible energy harvester mounted on the test fixture such as a vibration exciter or
linear motor. The readings of the output voltage or current on the display of the meters are
carefully taken with the induced bending, stretching, or twisting motion measured by the
accelerometer.
NOTE A flexible energy harvester can be measured as shown in Figure 3. After mounting the energy harvester
onto a linear motor, the electrical characteristics are measured by using a meter or equivalent equipment. If the
measurements are satisfactory, a reliability test for the temperature range with thermal cycling and mechanical
failure with various bending, stretching or twisting motions, is performed for commercial use.

– 12 – IEC 62830-4:2019 © IEC 2019

Key
Procedure Reference subclause Procedure Reference subclause
Start  Mechanical characterization
Electrical characterization Flexibility 3.1.1
Input 3.3.9 and 5.2.17 to
Capacitance 3.2.5 and 5.2.2 bending/stretching/twisting 5.2.19
motion
Output voltage 5.2.9 Temperature range 3.3.7 and 5.2.15
Output power 3.3.4 and 5.2.11 Humidity range 3.3.8 and 5.2.16
Optimal load 3.3.6 and 5.2.12 Mean-time-to-failure 3.3.10
Maximum output power 5.2.13
Figure 3 – Measurement procedure of flexible piezoelectric energy harvesters
5.2 Electrical characteristics
5.2.1 Test procedure
Figure 4 shows a test setup of the electrical characteristics of a flexible piezoelectric energy
harvester. To measure the electrical characteristics of a flexible piezoelectric energy
harvester, the device should be mounted on a linear motor/vibration exciter as shown in
Figure 4. When periodic signal input waveforms (sinusoidal, rectangular, triangular, sawtooth,
etc.) with specified frequency and acceleration are applied to the device at the condition of a
continuous bending, stretching, or twisting motion, an output voltage across an external load
and short current are measured. The input motion (stress) being used to characterize the
devices can be selected as the possible applications of the devices. The direction of
deformation depends on the geometrical structure of the harvester and direction of applied
acceleration. A periodic sinusoidal waveform of 1 Hz frequency and 1 g acceleration is the
input during all the experimental data presented here.
The following test procedure is performed:
a) A specified bending, stretching, or twisting motion is induced to the energy harvester.

b) The voltage across or current through the external load which is connected to the
terminals of the energy harvester is measured using a voltage or current meter,
respectively.
c) The voltage and current are measured under various accelerations of bending, stretching,
or twisting motion by adjusting the amplifying ratio of the controller.
d) The voltage and current are measured between the top and bottom electrodes or comb
structured electrode through forward and reverse connection at the specific range of strain.
e) The voltage and current are measured with various induced strain ranges and frequencies.
f) The voltage and current are derived from various external loads to find the optimal load.
NOTE In the random excitation experiments, the base excitation is intended to cover a broad range of excitation
frequencies to be as close to white noise as possible within the limitations of the electromechanical shaker and
other hardware.
Key
Component and meters to monitor Equipment and supplies
DUT: device Piece of energy harvester Controller To supply a specified frequency of
under test electrical signal to the linear motor

Voltage meter (V) To detect a voltage across the Linear motor/ To supply a specified level and
external load frequency of
vibration
bending/stretching/twisting motion to
exciter
a piece of DUT
Ampere meter (A) To detect a current through the Stress & strain To detect an acceleration, force and
external load monitoring strain of the linear motor
External load (R) Load with specific impedance
Figure 4 – Test setup for the electrical characteristics of a flexible
piezoelectric energy harvester
5.2.2 Capacitance
It is a capacitance measured between two terminals of an energy harvesting device at a
specified frequency and voltage. A calibration of an LCR meter should be made in order to
eliminate systematic errors that have occurred in the LCR meter, cable, and connectors.
When the device is connected to the LCR meter, its capacitance will be displayed. When
measuring capacitance, the specified frequency and voltage for measurement should be
recorded.
– 14 – IEC 62830-4:2019 © IEC 2019
5.2.3 Open circuit voltage
It is the measured voltage resulting from the induced bending/stretching/twisting motion of the
energy harvester via its terminals without external load. When measuring the open circuit
voltage, the input impedance of the voltage meter should be recorded. Figure 5 shows a
typical graphical shape of a measured open circuit voltage versus time of an energy harvester
under constant input acceleration at constant frequency.

Figure 5 – Open circuit voltage of a flexible piezoelectric energy harvester
5.2.4 Short circuit current
It is the measured current resulting from the induced bending/stretching/twisting motion of the
energy harvester via its terminals with short circuit configuration. Figure 6 shows a typical
graphical shape of the short circuit current versus time measured at the energy harvester
under constant input acceleration at constant frequency.

Figure 6 – Short circuit current of a flexible piezoelectric energy harvester

5.2.5 Open circuit voltage with various induced strains
It is the measured voltage resulting from the induced bending/stretching/twisting motion of the
energy harvester via various induced strains. When measuring the open circuit voltage, the
input impedance of the voltage meter should be recorded. Figure 7 shows a typical graphical
shape of the measured open circuit voltage versus time with various induced strains at
constant input frequency, and the measured open circuit voltage versus strain of the energy
harvester.
a) Open circuit voltage versus time with various induced strains

b) Open circuit voltage versus various induced strains
Figure 7 – Open circuit voltage of the flexible piezoelectric energy harvester
with various induced strains
5.2.6 Short circuit current with various induced strains
It is the measured current resulting from the induced bending/stretching/twisting motion of the
energy harvester via various induced strains. When measuring the open circuit voltage, the
input impedance of the voltage should be recorded. Figure 8 shows a typical graphical shape
of the measured short circuit current versus time with various induced strains and the
measured short circuit current versus strain of the energy harvester.

– 16 – IEC 62830-4:2019 © IEC 2019

a) Short circuit current versus time with various induced strains

b) Short circuit current versus various induced strains
Figure 8 – Short circuit current of the flexible piezoelectric energy harvester
with various induced strains
5.2.7 Open circuit voltage with various induced frequencies
It is the measured voltage resulting from the induced bending/stretching/twisting motion of the
energy harvester via various induced frequencies. When measuring the open circuit voltage,
the input impedance of the voltage meter should be recorded. Figure 9 shows a typical
graphical shape of the measured open circuit voltage versus time with various induced
frequencies, and the measured open circuit voltage versus frequency of the energy harvester.

a) Open circuit voltage versus time with various induced frequencies

b) Open circuit voltage versus various induced frequencies
Figure 9 – Open circuit voltage of the flexible piezoelectric energy harvester
with various induced frequencies
5.2.8 Short circuit current with various induced frequencies
It is the measured current resulting from the induced bending/stretching/twisting motion of the
energy harvester via various induced frequencies. When measuring the open circuit voltage,
the input impedance of the voltage meter should be recorded. Figure 10 shows a typical
graphical shape of the measured short circuit current versus time with various induced
frequencies, and the measured short circuit current versus frequency of the energy harvester.

– 18 – IEC 62830-4:2019 © IEC 2019

a) Short circuit current versus time with various induced frequencies

b) Short circuit current versus various induced frequencies
Figure 10 – Short circuit current of the flexible piezoelectric energy harvester
with various induced frequencies
5.2.9 Output load voltage
It is the RMS value of the voltage measured across the terminals of the energy harvester with
a specified external load and induced bending, stretching, or twisting motion. Figure 11 shows
the graphical shape of the measured output voltage versus external resistive load connected
to the terminals of the energy harvester.

Figure 11 – Output load voltages of flexible piezoelectric energy harvester
at various external loads
5.2.10 Output current
It is the current measured through the specified external load connected to the terminals of
the flexible energy harvester at the specified induced bending, stretching, or twisting motion.
Figure 12 shows the graphical shape of the measured current versus output voltage of the
energy harvester. The short circuit current from the terminal of the energy harvester is the
RMS value of the measured current when the voltage across the energy harvester is zero.

Figure 12 – Output current of the flexible piezoelectric energy harvester
at various output voltages
5.2.11 Output power
Output power is calculated from the RMS value of the measured output voltage and current of
the energy harvester with external load.
P= IV [W] (2)
Figure 13 shows the graphical shape of the measured output power versus external load of
the energy harvester.
– 20 – IEC 62830-4:2019 © IEC 2019

Figure 13 – Output power of the flexible piezoelectric energy harvester
at various external loads
5.2.12 Optimal load impedance
Optimal load impedance is determined as the value of the external load when the output
power of the energy harvester is maximum.
5.2.13 Maximum output power
It is the maximum value of the output power measured from the energy harvester at a
specified maximum input bending, stretching or twisting motion. The maximum input bending,
stretching, or twisting motion is described in 5.2.17 to 5.2.19. Figure 14 shows the graphical
shape of measured output power and voltage versus various input bending, stretching, or
twisting motions.
Figure 14 – Output power and voltage of the flexible piezoelectric energy
harvester at various input bending, stretching, or twisting motions
5.2.14 Test procedure
Figure 15 shows a test setup of the reliability of the flexible piezoelectric energy harvester.
When a continuous bending, stretching or twisting motion is applied to the device, output
voltage or current is measured through an external load connected to the device.

To test the reliability, the following test procedure is performed:
a) a bending, stretching or twisting motion is induced to the energy harvester;
b) the output voltage or current of the energy harvester is measured by the meter.

Key
Component and meters to monitor Equipment and supplies
DUT: device under test A piece of energy Controller To supply a specified frequency
harvester of electrical signal to the linear
motor
Voltage meter (V) To detect a voltage Linear motor/ To supply a specified level and
across the external load frequency of bending motion to
vibration exciter
a piece of DUT
Ampere meter (A) To detect a current Stress & strain To detect an acceleration, force
through the external load monitoring and strain of the linear motor
External load (R) Load resistor Temperature controlled To keep a specified temperature
environment chamber value of a piece of DUT
Figure 15 – Block diagram of a test setup for evaluating the reliability of
the flexible piezoelectric energy harvester
5.2.15 Temperature range
The objective of this test is to evaluate the reliability of the device by a low/high temperature
cycling test. The temperature range should be specified from the applications. First, the test is
performed in the temperature cycling test chamber, where temperature is changed from
-40 °C to +100 ºC. The performance characteristics are monitored by a meter.
IEC 60749-5 applies.
– 22 – IEC 62830-4:2019 © IEC 2019
5.2.16 Relative humidity range
The objective of this test is to evaluate the reliability of the device by a low/high humidity test.
The humidity range should be specified from the applications. The test is performed in the
humidity cycling test chamber where humidity is changed from 10 % to 90 % with
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