1/19

RESULTS OF ASSESSMENT ON
ELECTROMAGNETIC INTERFERENCE DUE
TO WIRELESS POWER TRANSFERSYSTEMSTECHNICAL REPORTBWF TR-02 Edition 1.0

Published on March 14, 2016

Broadband Wireless Forum2/19

Preface
The Broadband Wireless Forum (hereinafter referred to as the “BWF”) was established on July 3,2009 to contribute to the quality development of new systems and services utilizing radio waves.
The forum has been performing various activities on wireless communications technologies,
such as the research, development, and investigation of new wireless technology, the collectionof information, liaison and coordination with related organizations, and dissemination andawareness-raising activities for the early realization and international expansion of systems andservices using new wireless communications technology. Technical information parts of theresults of these activities have been compiled and released as "technical reports."

In the area of wireless power transmission/transfer technology, a technical report titled
Guidelines for the Use of Wireless Power Transmission/Transfer Technologies was published in
April 2011. In states where we can expect the early, practical application of new wireless powertransmission/transfer technology due to steady progress, this report will serve as a set of
guidelines that specify basic matters with which product manufacturers and service providers
applying such technology should comply in order to improve convenience for users and toguarantee the safety of such users.

This technical report was compiled based on the results of assessment that were conductedunder a three-party framework composed of Hokkaido University, Japan Arrhythmia Device
Industry Association (hereinafter referred to as the “JADIA”), and the BWF from fiscal year 2011
to 2014 in order to clarify the influence of wireless power transfer systems on active implantable
medical devices.

We hope that these technical reports will be actively utilized by machine manufacturers, service
providers, and users.

3/19

Contents
Section

Page

1.

Scope

4

2.

Definitions

4

3.

Assessment method for electromagnetic interference

4

4.

WPT units used for assessment

6

5.

Results

7

6.

Conclusion

7

References
Related presentations

Annex A

Types and settings of AIMDs

9

Annex B

Criteria for evaluating influence levels

11

Annex C

Installation of WPT units and assessment procedure

12

Annex D

Specifications of WPT units (mobile devices) and detailed results

14

Annex E

Details of WPT units (EVs) and detailed results

16

Annex F

(Informative) Framework of electromagnetic interference assessement

19

4/19

RESULTS OF ASSESSMENT ON ELECTROMAGNETIC
INTERFERENCE DUE TO WIRELESS POWER TRANSFERSYSTEMS
1. Scope
This technical report was compiled based on the results of assessment that were conducted by
Hokkaido University, the JADIA, and the BWF from fiscal year 2011 to 2014 in order to clarify the
influence of wireless power transfer systems (WPTs) on active implantable medical devices(AIMDs). We conducted the assessment using implantable cardiac pacemakers and implantablecardiac defibrillators (ICDs) as the AIMDs.
2. Definitions
The definitions of the main terms used in this technical report are shown below.
2.1 Implantable cardiac pacemaker: An implantable medical device used to maintain an
adequate heart rate by electrically stimulating the heart; the main body (pulse generator)
has an electric circuit and a battery both embedded in its small metal case, and a thin
conducting wire called a “lead” is connected in order to convey electric stimuli sent from themain body to the heart. The pacemaker monitors the motion of the heart continuously. Whenthe pacemaker finds that the heart rate becomes pathologically slow, it sends weak electric
stimuli to the heart via the lead for correcting the heart rate by forcing the heart to contract insynchronization with such electric stimuli.
2.2 Implantable cardiac defibrillator (ICD): A medical device to treat a heart rate thatexceeds the normal rate (tachycardia); like a pacemaker, an ICD is configured of a main
body that has an electric circuit and a battery both embedded in a small metal case and a
conducting wire called a “lead” that conveys electric stimuli sent out from the ICD main bodyto the heart. Electroshock pulses with large energy are used for tachycardia treatment.

3. assessment method for electromagnetic interference
The configuration of equipment as well as the settings and modes of the devices (AIMDs) were
determined in the manner described in Investigation report on the influence of radio waves to
medical devices [1] published by the Ministry of Internal Affairs and Communications (Annex A).
To put it concretely, as shown in Fig. 1, an AIMD was placed in a torso phantom that was
designed to simulate a human body, and the AIMD was checked regarding whether or not it
malfunctioned when a WPT was brought close to the torso phantom. For the criteria to evaluate
the influence levels of malfunctions, refer to Annex B. While simulated ECG signals generated bya simulated ECG signal generator were input into the AIMD, the pacing signals generated by the5/19

AIMD were monitored with an AIMD monitor and an oscilloscope, and the results were recordedwith a chart recorder. Note that a torso phantom is an acrylic vessel in which a 0.18 g/l saline
solution is filled to simulate the electrical characteristics of a human body. Figure 2 shows anexample where an AIMD is placed in a torso phantom. Concrete information regarding the
installation of WPT units and the assessment procedure are described in Annex C.

Torso phantom

Pacemaker/ICD

Atrial electrodeAtrial signal> 2 kΩ

Pace pulse

Simulated ECG signal
generator/AIMD
monitor

Lead

Saline solution(1.8 g/l NaCl)
Ventricular electrode

Simulated ECG
Ventricular signal

Chart recorder(NEC Sanei RT3608)

Oscilloscope(Agilent DSO3202A)

Fig. 1: Evaluation system for electromagnetic interference on an AIMD (courtesy of Hokkaido
University)

34 cm
Saline solution(NaCl 1.8 g/l)
Cardiac pacemaker
Lead wire

Ventricular electrode

36 cm

Atrial electrodeFig. 2: AIMD installed in a torso phantom (courtesy of Hokkaido University)

6/19

4. WPT units used for assessment

The WPT units used for the assessment are summarized below. The assessment wereconducted by using 15 WPT units in total, which were comprised of products that wereavailable in the market at the time of testing and prototypes that were to be launched in the
future. For details, refer to Annexes D and E.
1.1 Magnetic field couplings (resonant type)1.1.1 Electric vehicles (EVs)
Frequency

85 kHzTransmitted power

Up to 3 kW

Number of units3

1.1.2 Mobile devices
Frequency

135, 400 kHz, 6.78 MHz

Transmitted power

Up to 18.2 W

Number of units

3

1.2 Magnetic field couplings
1.2.1 Mobile devices
Frequency

70, 110 to 210 kHz

Transmitted power

Up to 15 W

Number of units

7

1.3 Electric field couplings
1.3.1 Mobile devices
Frequency

200, 460 kHz

Transmitted power

Up to 40 W

Number of units

2

7/19

5. Results

The assessment results are shown in Table 1. For details, refer to Annexes D and E.
Influences were found with some units, even though the occurrence rates were very small. It
was confirmed that, however, the influences were reversible and disappeared when the unit
moved away from the torso phantom.
Table 1: Summary of assessment results

SystemApplication

EVs

Transmitted
power

Up to 3 kW

Magnetic
field
coupling

Mobiledevices

Electric field

Mobilecoupling

devices

Up to 5 W

Frequency
Up to 100

100 to 500

kHz

kHz

6.78 MHz

0/3
0/1

4/6

-

L2 / 2 cm

5 to 20 W

Up to 40 W

0/2

0/1

-

-

1/2
L2 / 1 cm

Upper rows: Number of models having influence / Number of assessment models
Lower rows: Influence level / Maximum distance at which interference disappeared
L2 (Level 2): Abnormal pacing/sensing for one cycle or longer

6. Conclusion
This technical report was compiled based on the results of assessment that were conductedunder a three-party framework composed of Hokkaido University, the JADIA, and the BWF fromfiscal year 2011 to 2014 in order to clarify the influence of wireless power transfer systems on
active implantable medical devices. Although influences were found with some models, all the
distances at which the interference disappeared were 2 cm or shorter even when the sensitivityof the AIMD was set to the maximum level, which indicates that no influence will occur unless the
WPT is brought very closely into intimate contact with the AIMD. We will continue assessment toaccumulate data as much as possible and will aim to contribute to the safe and secure use ofwireless power transfer systems.
Finally, we are deeply grateful to Emeritus Professor, Toshio Nojima and Assistant Professor,
Takashi Hikage at Hokkaido University, who gave us a great deal of assistance and advice
through actual assessment for investigating the influence of wireless power transfer systems on
active implantable medical devices.

8/19

We would also like to express our gratitude to various people from the Japan Arrhythmia Device
Industry Association, who, with good grace, provided us with the active implantable medical
devices to be used for the investigation.

References[1] Ministry of Internal Affairs and Communications, Investigation report on the influence ofradio waves to medical devices, March, 2007
http://www.tele.soumu.go.jp/resource/j/ele/medical/img/h18_report.pdf

Related presentations[1] Hikage, et al., "In vitro Assessments of Active Implantable Medical Devices EMI from Radio
Wave Emitted by Wireless Power Transfer Devices," IEICE General Conference, BI-4-4,
2014. (in Japanese)[2] Hikage, et al., “In vitro assessment of electromagnetic interference due to electric vehicle
wireless power transfer system on active implantable medical devices,” ISMICT2015, March,
2015.
[3] Hikage, et al., "Assessments of Electromagnetic Interference Due to Electric Vehicle
Wireless Power Transfer System on Active Implantable Medical Devices," IEICE Technical
Report WPT2015-29, 2015. (in Japanese)[4] Hikage, et al., "Example assessment on electromagnetic interference due to wireless powertransfer systems on implantable cardiac pacemakers/ICDs," NICT EMC-net, July, 2015. (inJapanese)[5] Onishi, "International trend in human body protection from wireless power transfer and EMI
on implantable medical devices," CEATEC Japan 2015, IEICE serial program, October,2015. (in Japanese)[6] Onishi, "Front line related to human body protection from radio waves emitted from wirelesscharging and mobile devices," EMC Forum 2015, October, 2015. (in Japanese)[7] Hikage, et al., “In-vitro assessment of electromagnetic interference caused by wirelesspower transfer system on active implantable medical devices,” KJJC2015 in Sendai, Nov.
2015.

9/19

Annex A

Types and settings of AIMDs

In this assessment, the following types of AIMDs were used.
•

Implantable cardiac pacemaker (pacemaker) – dual-chamber
An implantable medical device used to maintain an adequate heart rate by electricallystimulating the heart•

Cardiac re-synchronization therapy pacemaker (CRT-P) – triple-chamber
CRT: Cardiac re-synchronization therapy•

Implantable cardiac defibrillator (ICD) – single- or dual-chamber
A medical device to treat a heart rate that exceeds the normal rate (tachycardia);electroshock pulses with large energy are used for treatment.

•

Cardiac re-synchronization therapy defibrillator (CRT-D) – triple-chamber
Categorized as the ICD

Table 1 shows the list of modes used for EMI assessement. In the assessement, thesensitivity of the AIMD was set to the maximum level initially, and was then lowered
step-by-step when influence was found. As a result, the AIMD was assessed at up to
five sensitivity steps (the maximum sensitivity, 1.0 mV, 2.4 mV, 5.6 mV, and the minimum
sensitivity).

Table 1: Electromagnetic interference assessement modes
VVI
In.

VVI
As.

AAI
In.

AAI
As.

UNI

BI

UNI

BI

UNI

BI

UNI

BI

BI

BI

Total
number ofmodes

Pacemaker(per model)

1

1

1

1

1

1

1

1

-

-

8

ICD
(per model)

-

1

-

1

-

1

-

1

2

2

8

FP.

FN.

The details of the modes are as follows.
Operation modes•

VVI: Using the ventricle electrode, the AIMD generates electric stimuli when noventricle native rhythm can be detected within a predetermined period of time.

•

AAI: Using the atrium electrode, the AIMD generates electric stimuli when no
atrium native rhythm can be detected within a predetermined period of time.

10/19Pacemaker/ICD common test modes (test modes for the pacing function)•

Inhibit test (In): A test mode where no signal is input from the simulated ECG signal
generator; the AIMD senses the absence of generated normal signals (ECG)
and generates pacing pulses to stimulate the heart. When the influence ofelectromagnetic interference occurs, the pulses that should be generated by the
AIMD will not be generated.

•

Asynchronous test (As): A test mode where a signal is always input from thesimulated ECG signal generator; the AIMD senses generated normal signals(ECG) and suppresses pacing pulses from the AIMD. When the influence ofelectromagnetic interference occurs, the pulses that should be suppressed by
the AIMD will be generated.

ICD test modes (test modes for the defibrillation function)•

False-positive test (FP): This test checks whether or not the ICD makes a false
detection of ventricular fibrillation or ventricular tachycardia during inhibit andasynchronous tests above. When the influence of electromagnetic interference
occurs, the ICD will wrongly generate defibrillation pulses.

•

False-negative test (FN): This test checks whether or not the ICD can normallydetect a signal simulating ventricular fibrillation that is input from the simulated
ECG signal generator. When the influence of electromagnetic interference
occurs, the defibrillation pulses that should be generated by the ICD will not be
generated.

Configuration of leads•

Unipolar (UNI): Sensing and paging are carried out by using the AIMD main body(made of metal) and the inner conductor of a lead.

•

Bipolar (BI): Sensing and paging are carried out between the inner and outerconductor of a lead.

11/19Annex B

Criteria for evaluating reaction levels

The criteria that the Ministry of Internal Affairs and Communications has been using for
pacemakers and ICDs were used as the criteria for the reaction evaluation [1]. The degrees ofinfluence for ICDs are the same as those for pacemakers.

Table 1: Reaction level vs. clinical significance on patients (pacemakers)

Reversible
reaction

Normal state

Normal operations maintained

Irreversible reaction
Externally
removable

Direct reaction onliving bodies

Replacement
surgery required

Level 0Abnormal pacing/sensing within one
cycle (recovered within 2 seconds)

Level 1

Abnormal pacing/sensing for one
cycle (2 seconds) or longer

Level 2

Pacemaker reset
Permanent change in program settings

Level 3

Persistent failure

Level 5

Permanent failure

Level 5

Induction of electromotive
force/heat in the lead

Level 5

Level

Degree of reaction (conventional classification)0

No reaction

1

Reactions that could cause instantaneous palpitations or dizziness

2

Reactions that could cause persistent palpitations or dizziness, from which the patient can recover with
their own action, such as by removing themselves from that location

3

Reactions that can deteriorate the patient's condition if left as-is

4

Reactions that can deteriorate the patient's condition immediately

5

Reactions that can bring the patient's life to a critical condition

Table 2:Reaction level vs. clinical significance on patients (ICDs)

Normal state

Normal operations maintained

Reversible
reaction

Irreversible reaction
Externally
removable

Level 1

Abnormal pacing/sensing for one
cycle (2 seconds) or longer

Level 2

Temporary loss of defibrillation
detection ability

Level 3Occurrence of unnecessary
defibrillation shocks

Level 4

Permanent change in program
settings

Level 4

Persistent failure

Level 5

Induction of electromotive
force/heat in the leadReplacement
surgery required

Level 0Abnormal pacing/sensing within one
cycle (recovered within 2 seconds)

Permanent failure

Direct reaction onliving bodies

Level 5
Level 5

12/19Annex C

Installation of WPT units and assessment
procedureThis annex explains how to install WPT units and their assessment procedure.

Figure 1 shows how a WPT unit other than an EV should be installed. For EVs, refer to Annex E.
The following describes the scanning procedure of WPT units.

1

Place the WPT unit around the center of the phantom. At that time, make sure that the
distance between the WPT unit and the phantom is 0 cm (i.e., that they are in intimatecontact).

2

Move the unit in such a way as to scan the surface of the phantom, and check whether
or not influence occurs. When influence occurs, record the position.

3

At the position where the influence occurs, locate the unit away from the phantom by 1
cm at a time and record the maximum distance at which the influence occurs.

Wireless charger
Transmitter

10 mm
Maximum
distance at
which
influence
disappears

Receiver
AIMD

AIMD
Lead
360 mmWireless charger

Lead
Electrode
340 mmFig. 1: Torso phantom and WPT unit (courtesy of Hokkaido University)

In the next place, Fig. 2 shows the test procedure. The summary is as follows.

1

Set the parameters of the WPT unit and the AIMD. There are two modes for the WPTunit: stand-by mode (where no power-receiving unit exists) and charging mode (wherea power-receiving unit is being charged). The initial setting of the AIMD sensitivity
should be the maximum.

13/192

Move the unit in such a way as to scan the surface, and check whether or not
influence occurs.
2.1

When no influence is found, proceed to the next condition.

2.2

When influence is found, determine the distance at which the influence
disappears.

3

When influence is found, reduce the sensitivity and repeat.
3.1

When no influence is found, proceed to the next condition.

Setting of test parameters(e.g., AIMD sensitivity [five steps, initial setting: maximum], leadpolarity)

Asynchronous test

Inhibition test
The test is conducted with the AIMD, to which no simulated
ECG is input (V-OUT: OFF), generating output pulses at apredetermined rate (with a wire to the chart recorder).

The test is conducted with the AIMD detecting ECGs thatare 10 to 20% higher (75 ppm) than the predetermined rate
(V-OUT: ON) so that the output pulses are suppressed.

Place the WPT unit close to the phantom.

Increase the distance
between the charger and thephantom (by 1 cm at a time).

Move the WPT unit in such a way as to scan the surface ofthe phantom, and check whether or not influence occurs.

Yes
Influence found?

No
When the test is completed, record (1) the distance at which the
influence disappears, (2) the influence level, and (3) the situation
when the influence occurs. With ICDs, check and record (4)whether or not false-positive and false-negative influences exist.

Reduce the sensitivity of the
AIMD by one step
(maximum sensitivity to 1.0
mV, 2.4 mV, 5.6 mV, and tominimum sensitivity).

Yes

Influence found andminimum sensitivity notreached?

No
End of test

Fig. 2: assessment procedure14/19Annex D

1

Specifications of WPT units (mobile devices) anddetailed results

WPT units used for assessment

The WPT units were selected from products that were already available in the Japanesemarket and from prototypes that were to be launched in the future. The major parametersthat should be taken into account are the charging system, frequency, and output. Table 1
shows a summary of the WPT units for mobile devices, excluding EVs.
Table 1: Specifications of the WPT units
Unit

Charging system

Frequency

Transmitted

under

power

test
A

Magnetic field coupling

70 kHz

0.2 W

BElectric field coupling

200 kHz

13 W

C

Magnetic field coupling

110 to 183 kHz*Up to 15 W

D

Magnetic field coupling

110 to 210 kHz*Up to 15 W

E

Magnetic field coupling

110 kHz

5W

F

Magnetic field coupling

110 kHz

5W

G

Magnetic field coupling

110 kHz

5 W x2H

Magnetic field coupling

110 kHz

5W

I

Electric field coupling

460 kHzUp to 40 W

J

Magnetic field coupling

400 kHzApprox. 0.4 W

K

Magnetic field coupling

6.78 MHz18.2 W

L

Magnetic field coupling

134.5 kHzApprox. 1.4 W* Differs depending on the operation mode
2

AIMDs used for assessment

JADIA provided models that were available in the period of time of assessment as the
AIMDs. Table 2 shows the number of models for each unit under the assessment.
Table 2: Number of AIMD models
Unit

Pacemaker

CRT-P

ICD

CRT-D

A to D

11

2

5

7

E to H

11

5

8

8

I

10

2

6

7

15/19

3

J, K

11

3

7

9

L

11

3

8

8

Results
Table 3: Summary of results
Model

Results: Level, distance at which reaction disappears (number of influencemodes/number of modes)
Pacemaker

ICD

A

No influence (0/208)

No influence (0/192)

B

L2 / 1 cm / (2/208)

No influence (0/192)

C

No influence (0/208)

No influence (0/192)

D

No influence (0/208)

No influence (0/192)

E

L1 / 1 cm / (3/620)

No influence (0/600)

F

No influence (0/620)

L1 / 1 cm / (1/600) *G

L1 / 1 cm / (3/620)

No influence (0/600)

H

L1 / 1 cm / (1/620)

No influence (0/600)

L2 / 1 cm / (1/620)
I

No influence (0/96)

No influence (0/104)

J

No influence (0/336)

No influence (0/384)

K

No influence (0/224)

No influence (0/256)

L

L2 / 2 cm / (1/448)

No influence (0/512)* Only in pacemaker mode

16/19Annex E1

WPT units used for assessment

Unit
M
N

2

Details of WPT units (EVs) and detailed results

Charging
systemMagnetic
field coupling
Magnetic
field coupling

Table 1: Specifications of the WPT units
Frequency
Transmitted power
85 kHz2 to 3 kW

85 kHz

3 kW

Conditions
Simulator wheeled
platform/real vehicle
Real vehicle

AIMDs used for assessment
Table 2: Number of AIMDs

3

Unit

Pacemaker

CRT-P

ICD

CRT-D

M, N

5

2

5

5

WPT layout

Figures 1 and 2 show the WPT layout for assessment with a simulator wheeled platform anda real vehicle, respectively.
Power unit

Simulator
wheeledplatform

Receiving coilTransmitting coil
LoggerFig. 1: WPT layout with a simulator wheeled platform (courtesy of Hokkaido University)17/19Power unit

Actual vehicle

Load

Receiving coilTransmitting coilFig. 2: WPT layout with a real vehicle (courtesy of Hokkaido University)
4

Assessment procedure
4.1

While changing the height and the orientation of the phantom, check theoperation of the AIMD. With reference to the midpoint of the distance between thetransmitting coil and the receiving coil, the layout consists of three points at thecenter (A), 25 cm (B), and 50 cm (C) (Fig. 3).

4.2

Starting the test at a position 1 m away, move the phantom to the point that is theclosest to the coil unit. Figure 4 shows pictures of a scene in which a simulator
wheeled platform was used.

4.3

Record the distance of the point at which influence was first found as theinfluence distance.

4.4

In tests where a real vehicle is used, assuming that a passenger is in the cabinduring charging, conduct the test not only at the back of the vehicle (scenario A)
and at the side of a rear wheel (scenario B), but also at the center of the rear seatof the vehicle (scenario C), which is closest to the coil position (Fig. 5).

C

Receiving coil
25 cm

B

25 cm
Phantom
A

Floor

Fig. 3: Positional relationship between the WPT and the phantom

18/19Chart recorder
Simulated
ECG signal
generator

Simulator
wheeledplatform
Phantom

Movement
direction

Fig. 4: Scene in which a simulator wheeled platform was used (courtesy of
Hokkaido University)

Fig. 5: Scene in which a real vehicle was used (courtesy of Hokkaido University)
5

Results
Table 3: Summary of results
Model

Results: Level, distance at which reaction disappears (numberof influence modes/number of modes)
Pacemaker

ICD

No influence (0/56)

No influence (0/80)

M (real vehicle)

No influence (0/56)

No influence (0/80)

N (real vehicle)

No influence (0/56)

No influence (0/80)

M (simulator wheeled
platform)19/19Annex F

(Informative) Framework of electromagnetic
interference assessment

The BWF and the JADIA provided Hokkaido University with WPTs and AIMDs,
respectively, asking for the conducting of electromagnetic interference (EMI)assessment.

Table 1: Framework of assessment
In charge
Interference sources (WPTs) provider

BWF

Units (AIMDs) provider

JADIA

EMI assessment

Hokkaido University