a literature survey on wireless power transfer for biomedical...

Review ArticleA Literature Survey on Wireless Power Transfer forBiomedical Devices

Reem Shadid and Sima Noghanian

Electrical Engineering Department, University of North Dakota, Grand Forks, ND 58203, USA

Correspondence should be addressed to Reem Shadid; [email protected]

Received 27 December 2017; Revised 26 February 2018; Accepted 6 March 2018; Published 12 April 2018

Academic Editor: Giuseppina Monti

Copyright © 2018 Reem Shadid and Sima Noghanian. This is an open access article distributed under the Creative CommonsAttribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original workis properly cited.

This paper provides a review and survey of research on power transfer for biomedical applications based on inductive coupling.There is interest in wireless power transfer (WPT) for implantable and wearable biomedical devices, for example, heartpacemaker or implantable electrocardiogram (ECG) recorders. This paper concentrates on the applications based on near-fieldpower transfer methods, summarizes the main design features in the recent literature, and provides some information about thesystem model and coil optimization.

1. Introduction

Implantable medical devices such as cochlear implants,cardiac defibrillators, electrocardiogram (ECG) implantedrecorders, and pacemakers play an important role in moni-toring treatment of various diseases. These devices interactwith physiological processes including sensing, drug delivery,and stimulation, to monitor or influence their progression.However, minimizing the size of implanted devices makesthem less invasive to human body and decreases the surgicalcomplexity in order to install them easily inside the body.While recent progress in microfabrication has dramaticallyminimized the size of electronic and mechanical compo-nents, electrochemical energy storage has been much slowerto miniaturize. In most existing devices, the battery consti-tutes the bulk of the implant [1]. In addition, surgical pro-cedures for replacing the batteries and the risk of leakageare the major disadvantages of using them [2]. Wirelesspower transfer (WPT) is used to transmit power to helpavoid these problems.

InWPT, an external power source will transmit energy tothe implanted power receivers. Although many techniques,such as optical and ultrasound methods, have been launched

to transfer power wirelessly, wireless powering throughradio-frequency (RF) electromagnetic waves is the mostestablished one.

Section 2 of this paper gives a general overview of theWPT methods based on induction methods. Section 3 pre-sents the concept of inductive coupling and illustrates thecircuit models for biomedical WPT applications. Section 4provides the comparison list of the research works that aresummarized in a tabular format in the Appendix. Powerefficiency (η) and optimization methods that are achievedin researcher publications are summarized too. Section 5provides the conclusions.

2. A General Review onWireless Power Transfer

Nikola Tesla was the leader of WPT. In 1891, he successfullyperformed an experiment to energize a lamp using a pair ofcoils. Later, he successfully performed similar experimentson two hundred lamps and transmitted power to them overa 25-mile distance [3].

WPT can be categorized into twomethods: near-field andfar-field transmission. Table 1 shows a comparison betweenthese two methods. In general, near-field power transfer

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methods have higher η in comparison to the far-fieldones. Most of the WPT applications are using the near-field method. In order to consider any region to benear-field, two conditions should be considered: first, thedistance between the transmitter and receiver coil (r)should be less than one wavelength (λ) at the operatingfrequency (r < λ), and secondly, the largest dimension ofthe transmitter coil should be less than λ/2. For implantablebiomedical device applications based on far-field transfer, agood review may be found in [4]. The far-field methods arebased on delivering power to a device using antennas. In thispaper, the focus is on the applications of near-field powertransfer methods.

Most biomedical near-field WPT methods use operatingfrequencies within the range of 100 kHz to 50MHz. Compar-ing the wavelength at this range with the typical transmis-sion, which is between 1 cm and 11 cm, the correspondingλ of the electromagnetic field is relatively long. Therefore,the transfer can be viewed as a near-field progress [5]. Thereare three major ways to accomplish a near-field WPT: (1)capacitive coupling based on electric fields, (2) inductive cou-pling based on magnetic fields, and (3) magnetic resonantinductive coupling.

WPT by inductive coupling and resonant coupling isthe main alternative to power implantable devices [6].The survey provided in this paper is mainly focused onthe studies that considered an inductive method to deliverpower wirelessly to biomedical devices.

The first reported use of inductive power transfer(IPT) was in the 1960s [7]. This paper introduced IPTto transfer power to an artificial heart. Since then, manyimplantable devices have used similar methods for powertransfer. In the 1970s, IPT was used in other biomedicalapplications [2, 8–16].

In the late 1970s, IPT was used to transfer highlevels of power. Some projects were launched in the1980s, but they were unsuccessful due to the rating ofsemiconductor devices used in the power supply thatlimited the use of high frequencies and η [17]. In themid-1990s, IPT was successfully commercialized in manyapplications [18]. Nowadays, the WPT based on IPT is stilldeveloping in many areas. This paper concentrates onbiomedical applications.

3. Inductive Coupling Concept and WirelessPower Transfer Models forBiomedical Devices

An IPT system consists of two coils referred to as the“primary” and “secondary” coils. Figure 1 shows the systemmodel. Power transfer occurs when a primary source

generates magnetic and electric fields, H and E , respectively,that induce voltage V at the secondary receiver

V = jωμ H ⋅ ds, 1

where ω is the operating angular frequency and μ is the per-meability of transfer medium. According to (1), couplingbetween coils mainly depends on the amount of magneticflux linkage between the primary and secondary coils.Decreasing the distance between the primary transmitterand secondary receiver while increasing the length of thecoils helps to increase the amount of magnetic flux. If the pri-mary and secondary coils are not well aligned, efficiency (η)will drop down causing more power loss.

A power transfer system block diagram for biomedicalsystems is shown in Figure 2. This system has three compo-nents; the first component is the power transmitter. Thepower transmitter is located outside the body. It may alsobe worn or placed in a distant location, for example, in aroom under the floor, chair, or bed. The power transmittercircuit consists of DC source, a DC-AC converter (whichenables transfer of power at the proposed operating fre-quency), a tuning circuit, a power antenna which allows thedata connectivity to send data to the receiver and also as afeedback to receive information sending by the implanteddevice, and a primary power coil (which allows the powertransfer). The second component is the power receiver whichis implanted inside the body below the tissue or even patchedon human skin. The receiver receives the wireless power andprovides a stable energy to the load or use the energy tocharge a battery. The receiver circuit consists of a secondary

Table 1: Comparison of WPT methods.

Method of WPT Frequency Directivity Range Penetration η

Near field Low Hz to MHz Weak Short Strong High

Far field Medium MHz to THz Medium to strong Long Medium to weak Medium to low

Figure 1: Inductive coupling principle.

2 International Journal of Antennas and Propagation

power antenna, a tuning circuit, an AC-DC converter, a DC-DC converter (regulator), and a power management unit tointeract with the transmitter through the implanted antenna.The third component is the middle power resonator. Thiscomponent is used as a third part to resonate at the operatingfrequency and to help deliver power to farther distanceplaces. It could also be worn or located at the receiver circuitunder the human body. This component is not mandatoryfor all WPT system design.

The main goal to be achieved by any WPT design is totransfer power with high efficiency and power stability. Thereare five main challenges facing that. The first challenge is thetransmitter’s and receiver’s size; as the receiver will be locatedinside the human body, its size will be limited. This small sizewill affect the quality factor and will decrease the couplingcoefficient and η accordingly. The second challenge is theoperating frequency; as the operating frequency increases,η will increase, but that will increase the energy loss inhuman tissue, which is causing increased heat that can be asafety issue. The third challenge is the ratio between thetransfer distance and the antennas size. As the distanceincreases, η decreases. The fourth factor is the lateral andangular misalignments between the transmitter and thereceiver antennas, which cause degradation of the couplingfactor and as a result, η will decrease too. The fifth challengeis the required power level by the receiver. For low powerlevel application, the main issue is how to transfer power withhigh η, since efficiency decreases as the power level decreases.On the other hand, the challenges for high power applica-tions are to avoid the thermal issue at the transmitter coil sideand how to keep the electromagnetic energy absorbed by thebody tissues as low as possible.

4. Prior Art

Tables 2–4 present the collection of papers on this topic.These papers are focused on the research topics of wire-less power transfer for biomedical applications. Thepapers are sorted in a descending order based on the yearthey were published. If two papers have the same year ofpublication, they are sorted based on operating frequencyused in the methodology. The design criteria of these papersare as follows.

4.1. Size Optimization Method for Transmitter and Receiver.Optimization methods to determine the transmitter andreceiver coil dimensions are used to increase the couplingcoefficient and to determine the optimal frequency toimprove η. Probably, one of the major challenges with bio-medical wireless power transfer is the restrictions on the sizeof devices. The devices are implanted in layers of body tissue.The maximum size may lay between a few to tens of millime-ters. The receiver is usually in a small packaging. As an exam-ple, capsule endoscopy is taken orally. The size of this capsuleis between 11mm to 27mm in general applications [5]. Theoptimum antenna shape and dimensions for both the trans-mitter and receiver should be predicted based on optimumoperating frequency and the gap range that is needed topower it.

Basic optimization for transmitter coil could be per-formed in two ways which most of the collected paperstarted with. The first one considers that the transfer dis-tance is known (x is fixed and constant). This method issuitable for medical applications where the device isimplanted in a certain place under the skin and within tissuelayers. Based on that, the optimum transmitter coil radius (a)is calculated using (2). This equation is derived by calculating

the maximum generated H field by the transmitter coil atcertain distance [5].

a = 2x 2

The second optimization method is presented for thoseapplications having portable or nonfixed receivers, with pre-dicted range such as capsule endoscopy. Transmitter coil

radius is optimized by calculating the integration of H (Ψ)within the transfer range (x) [5], based on the following:

Ψ =x2

x1H ⋅ dx =

x2

x1

INa2

2 a2 + x2 3dx, 3

where I is the coil current in ampere and N is the number ofcoil turns. One example of the capsule endoscope is modeledon Matlab® to determine the optimum coil radius for a rangeof distance between the centers of transmitter coil and thecapsule endoscope (x1 – x2) that varies within 0–10 cm, in

Receiver

LoadTuningcircuit

Tuningcircuit

AC‑DCconverter

DC‑ACconverter DC source

DC‑DCregulator

Resonator

Transmitter

Dat

a

Pow

er

Figure 2: Model of WPT system for a biomedical device.

3International Journal of Antennas and Propagation

Table 2: Implantable power device modeled in tissue.

Ref Journal Year FrequencyOutputpower(mW)

Optimizationmethod forinductordimension

Transmitterdimension(mm)

Receiverdimension[mm]

Gap(mm)

η (%) Simulation model

[29]

IEEE Antennasand WirelessPropagation

Letters

2017

13.56MHz(power)and

910MHz(data)

Frequencydomain solverin CST MWS

doutT = 83.2dinT = 59.6Circular

(CST MWS)

doutT = 24.2dinT = 19.2Circular

(CST MWS)

16

17%for

powerlink

2mm skin, 2mmfat, 7mm bone,50mm tissue

[30]

IEEETransactionson PowerElectronics

2015 800 KHz 30e3Based on themethod in

[31]

doutT = 70dinT = 34

Circular litzwireFinite

element (FE)

doutR = 70dinR = 34

Circular litzwire (FE)

20 95

One layer of skin(performed its

effect onsimulation)

[32]

IEEETransactionson BiomedicalCircuits andSystems

2015 200MHz 0.224Follow flowchart in the

paper

doutT = 24Printedhexagon(HFSS)

doutR = 1Wire wound

(HFSS)12 0.56

Design waswrapped with a

10mm thick layerof beef

[23] Sensors 2014 13.56MHz 150Based on themethod in

[24]

doutT = 56dinT = 10

Printed spiral(Matlab,

HFSS, FE &SEMCAD)

doutR = 11.6dinR = 0.5

Printed spiral(Matlab,

HFSS, FE &SEMCAD)

632 to80

Three layers of70× 60× 6mm3,1mm skin, 2mmfat, 3mm muscle

[33]

IEEETransactionson IndustrialElectronics

2014 8.1MHz 29.8~ 93.3

Optimizationhas been done

only forfrequency

doutT = 30Printedsquare(HFSS)

doutR = 20Printedsquare(HFSS)

12~ 20 47.6 to65.4

Various types oftissue including

blood

[34]

“EuropeanSolid StateCircuit

Conference(ESSCIRC)”

2013 160MHz >183Based on themethod in[35, 36]

doutT = 14.5Printedsquare

(MomentumEM & HFSS)

doutT = 2.2Printedsquare

(MomentumEM & HFSS)

10 0.87.5mm of musclelayer, 2.5mm air

[21]

IEEETransactions

on Circuits andSystems

2013 13.56MHz 10Based on themethod in

[19]

60× 25Printedrectangle

(HFSS & CSTEM)

25× 10Printedrectangle

(HFSS & CSTEM)

10~ 50 0.16 to58.2

Receiversandwiched

between two layersof pork tissues

[36]IEEE ElectronDevice Letters

2013 6.78MHz 10Based on themethod in

[37]

doutT = 20Printedsquare(HFSS)

doutT = 4.5Printedsquare(HFSS)

5 and12

30 and4.3

One layer of muscletissue

[38]

IEEETransactionson BiomedicalCircuit andSystems

2009 13.56MHzBased on themethod in

[19]

doutT = 24dinT = 9.4Printedsquare(HFSS)

doutR = 10dinR = 7.2Printedsquare(HFSS)

10 30.84

Receiversandwiched

between two layersof muscle

[39]


2007 6.785MHz 1~ 10Follow flowchart in the

paper

doutT = 30Circular litz

wire

doutR = 30Circular litz

wire1~ 10 51 to

74One layer of skin

[40]

IEEETransactions


2005 1MHz 250

Coil effectiveseries

resistance(ESR)

formulations


wire


wire7 67

A tissue throughretinal prosthesis


steps of 1 cm. Figure 3 shows the results. For example, theoptimized transmitter radius for the transfer range from2 cm to10 cm is 7 cm.

The sixth columns of Tables 2–4 indicate the optimiza-tion method that each paper performed. The methods pre-sented in [19, 20] use custom-made methods for geometryoptimization. Methods presented in [21, 22] are based onthe optimization method described in [19]. This optimiza-tion method is used when the operating frequency of thedesign is known. This method applies five steps for optimiz-ing the dimensions of the transmitter and receiver antenna.The first step is to apply the design constraints for thereceiver. The second step is to set the initial values for coildimensions based onmanufacturing limitation and optimumtransmitter coil dimension described at the beginning of thissection. The third step is to optimize the size and fill factor forthe transmitter coil. The fourth step is to set the line widthand fill factor for the receiver coil side. The fifth step is toreturn back and reset the size and line width of the transmit-ter side. After that, iterations are going until the value of therequired tolerance of the η value is achieved.

The work in [23] follows Harrison’s method to optimizethe coil size [24]. Harrison’s method is used for designingplanar spiral pancake-shape coils. He concluded that themaximum η could be achieved by considering dinT = 0 18doutT and dinR = 0 75doutR , where dinT is the inner transmitterdiameter, doutT is the outer transmitter diameter, dinR is theinner receiver diameter, and doutR is the outer receiver diam-eter. The paper results are based on derived equations and anexperimental study, which was conducted using multiplecoils and their dimensions at maximum achieved η.

Reported research in [25, 26] did not include any optimi-zation process to calculate the geometries of coils.

4.2. Circuit Model and Efficiency Calculation. The simplifiedschematic model circuit of the resonant coupling inductivelink is shown in Figure 4. L1, R1, and Cp1 are the self-induc-tance, resistance, and capacitance of the transmitter coil,respectively. L2, R2, and Cp2 are the self-inductance, resis-tance, and capacitance of the receiver coil, respectively. RLis the load resistance. CS1 and CS2 are the added capacitanceon the transmitter and receiver part, respectively. Thehighest voltage gain and efficiency (η) could be achieved

when both inductors (L1 and L2) and total equivalent capac-itors (C1 and C2) from the transmitter and receiver are tunedat the operating frequency according to the following:

ω0 =1L1C1

=1L2C2

, 4

where C1 ≈ CS1 and C2 ≈ CS2 + Cp2; the delivered power toprimary LC tank is divided between the transmitter coil resis-tance R1 , and the secondary load RL . The primary resis-tance converts the power to heat, and the power istransferred into the secondary coil through their mutualinductance (M). M is related to the coupling coefficient kaccording to the following:

k =M

L1L25

The quality factors for the transmitter (Q1), receiver (Q2),and load (QL) circuit are calculated as follows:

Q1 =ω0L1R1

,

Q2 =ω0L2R2

,

QL =RLω0L2

6

The total AC-AC efficiency (η) is calculated according tothe following:

η =k2Q1Q2

1 + k2Q1Q2 + Q2/QL×

11 + QL/Q2

7

Consequently, maximum achievable efficiency (ηmax) isgiven by

ηmax =k2Q1Q2

1 + 1 + k2Q1Q22 8

Details of derivation of (7) and (8) can be found in [27].The efficiency of DC-DC depends mostly on the efficiencyof converters and is calculated as the product of η and theconverter efficiency.

Table 2: Continued.


Optimizationmethod forinductordimension


Receiverdimension[mm]

Gap(mm)

η (%) Simulation model

[41]

IEEETransactions


2005 1MHz >250doutT = 40dinT = 32Disk

doutR = 22dinR = 18Disk

7 and15

33.3 to65.8

A tissue throughretinal prosthesis

[42]ELSEVIERSensors andActuators

2004 700 KHz 50

Using a self-developeddesign tool

and equations

doutT = 60Pancake/disk(FastHenryand Matlab)

doutR = 20Solenoid

(FastHenryand Matlab)

30 36 One layer of skin


Table 3: Implantable power device modeled in air.


Optimizationmethod forthe inductordimension


Receiverdimension(mm)

Gap(mm)

η (%)Simulationmodel

[32]


2015 200MHz 0.224Follow flowchart in the

paper

doutT = 24Printed

hexagonal(HFSS)

doutR = 1Wire wound

(HFSS)12 1.02 Air

[34]

“European SolidState CircuitConference(ESSCIRC)”

2013 160MHz >183Based onthe methodin [35, 36]

doutT = 14.5Printed square(MomentumEM & HFSS)


10 1.5 Air

[43]

Hindawi: Activeand PassiveElectronic

Components

2012 211.9 KHz 125Based onthe methodin [42]

10 12.5 Air

[44]

“Proceedingsof the AnnualInternationalConferenceof the IEEE

Engineering inMedicine andBiology Society,

EMBS”

2011 13.56MHz 27Based onthe methodin [19]

doutT = 27dinT = 11

Printed spiral

12× 10Rectangle

Wire wound litz7

Air, wornas a jacketon back of

a rat

[45]


2011 13.56MHz

49.5

Followflow chartin the paper

2 coildoutT = 37

Printed spiral(HFSS)

2 coildoutR = 10


10

75.7

Air43.4

3 coildoutT = 43


3 coildoutR = 10


78.63 coil

3.9

4 coildoutT = 36.5Printed spiral

(HFSS)

4 coildoutR = 10


83.54 coil

[25]ELSEVIER:Procedia

Engineering2011 1MHz 380

Area = 1000mm2

Spiral litz wireArea = 520mm2

Spiral litz wire10 50 Air

[20]

IEEETransactionson Bio Circuitsand Systems

2011 700KHz 100Follow flowchart in the

paper

doutT = 64Spiral litz wire

(Spice)

doutR = 22Spiral litz wire

(Spice)20 82 Air

[46]

“2010 3rd

InternationalSymposiumon AppliedScience in

Biomedical andCommunicationTechnology”

2010 27MHz 794

Coil builtbased on[47], no

optimizationused

doutR = 15Square (CST

MWS)15 80 Air

[48]

IEEETransactionson Circuitsand Systems

2010 13.56MHz 11.2Based onthe methodin [19]

doutT = 20dinT = 10

Printed square

doutR = 10dinR = 6

Printed square5~ 20 1 to

14.1Air


Table 3: Continued.


Optimizationmethod forthe inductordimension


Receiverdimension(mm)

Gap(mm)

η (%)Simulationmodel

[49]


2010 13.56MHzBased onthe methodin [19]

doutT = 79dinT = 11.2

Printed square(HFSS)

doutR = 10dinR = 2.96


10 56.65 Air

[22]

“IEEEInternationalSolid-StateCircuits

Conference”

2009 13.56MHz 7.05Based onthe methodin [19]

doutT = 168Printed hexagon

(HFSS)

doutR = 30Wire wound

solenoid (HFSS)70 80.2 Air

[38]

IEEETransactionBiomedical

Circuit System

2009 13.56MHzBased onthe methodin [19]





10 72.22 Air

[24]

“2007 IEEEInternationalSymposiumon Circuitsand Systems”

2007 6.78MHz <100 dinT ≈ 0.18doutTdinR ≈ 0.75doutR

doutT = 52dinT = 10

Printed spiral

doutR = 10dinR = 5

Printed spiral15

10 to20

Air

[19]


2007

1MHzFollow flowchart in the

paper

doutT = 69dinT = 8


doutR = 20dinR = 8


10

41.2

Air

5MHz

doutT = 70dinT = 8


doutR = 20dinR = 8


85.8

[50]


2007

125KHz

125Based onthe methodin [51]

doutT = 36dinT = 13

Spiral litz wire(FastHenry-2)

doutR = 26dinR = 12


10 50

Air125KHz

doutT = 64dinT = 14


doutR = 22dinR = 6


18 50

500KHz

doutT = 44dinT = 14


doutR = 22dinR = 7


10 29.9

[51]

IEEETransactionson BiomedicalEngineering

1996 2MHz dinT ≈ 0.4doutT

doutT = 24dinT = 22.5Spiral

doutR = 24dinR = 22.5Spiral

1~ 25 5 to90

AirdoutT = 15.86dinT = 13.58

Spiral

doutR = 15.86dinR = 13.58

Spiral

doutT = 24With 3.55 turn

spiral

doutR = 24With 3.55 turn

spiral

[52,53]

IEEETransactionson PowerElectronics

1992 53~123KHz 48e3Based onthe methodin [54, 55]

Area = 37mm2 Area = 37mm2 10~ 20 72 to76

Air


4.3. Summary of Achieved Performances. Figure 5 shows theefficiency versus the output or delivered power that thereceiver collects from the transmitter for the papers listedin Tables 2, 3, and 4. It should be noted that the efficiencyincreases at high delivered power. However, various efficien-cies may have been achieved for the same delivered powerdepending on the system design.

Figure 6 presents the graph of efficiency versus frequency.It is clear that the frequency for most of the biomedical

devices in the papers reviewed in this survey is below50MHz.

4.4. Future Directions. Nowadays, the focus is on miniaturiz-ing implantable devices to reduce surgical complexity andinfection risk. Electromagnetic energy transfer enables trans-cutaneous communication and powering with fully implant-able wireless biomedical devices [28]. The main goal of WPTis to provide sufficient power to the implanted device whileminimizing tissue heating due to the absorbed energy. This

Table 4: Other model of implantable power device.


Optimizationmethod forinductor

dimensions

Transmitterdimension(mm2)

Receiverdimension(mm2)

Gap(mm)

η(%)

Simulationmodel

[34]

“European SolidState CircuitConference(ESSCIRC)”

2013 160MHz >183Based onthe methodin [35, 36]



10 1

7mm of 0.2molar NaCl

layer and 3mmair

[56]IEEE Transactionson BiomedicalEngineering

2012 13.56MHz 24Based onthe methodin [57, 58]

doutT = 480Circular

Built underfloor

Capsule13× 27 1000 3.04

Endoscopiccapsule

[26]ELSEVIER:Procedia

Engineering2010 300

Capsule16× 28

Freemove

Endoscopiccapsule

[38]IEEE TransactionBiomedical Circuit

System2009 13.56MHz

Based on themethod in [19]





10 51.8

Receiver placedbetween twolayers of saline

in

Radius of transmitter coil (m)

�휓 (A

)

00

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

7−10 cm6−10 cm

5−10 cm4−10 cm

3−10 cm

2−10 cm

1−10 cm

0−10 cm

Figure 3: Magnetic field integration for specified transfer range.

C2

RLL1 L2

C1

CS1

C P1

C P2

C S2

R1 R2M

Figure 4: Circuit model of inductive coupling.

0

20

40

60

80

100

0 10 20 30 40 50

Effici

ency

(%)

Delivered power (mW)

Figure 5: Efficiency versus delivered power.

0

20

40

60

80

100

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Effici

ency

(%)

Frequency (MHz)

Figure 6: Efficiency versus frequency.


has led to an extensive research toward maximizing effi-ciency, through optimizing operating frequency, coils geom-etries, impedance matching, and power delivery.

The last columns of Tables 2–4 summarize the modelsthat were considered as a medium surrounding theimplanted device. Future directions for research alsoinclude addressing the effects of expected variations inthe tissue medium and monitoring absorption in tissueto inform adjustments to transmit power, frequency, andimpedance matching.

5. Conclusion

This paper presents a short survey of WPT based on IPTconcept for biomedical applications. The delivered powerto biomedical devices reported in the collected papersranges from few mW to 48W, with maximum efficiencyof up to 95% for 20mm range.

Appendix

Table 2 presents the highlights of the research papers on theimplanted power devices for medical applications that aremodeled in tissue layers. Table 3 shows the highlights of theresearch on the implantable systems that are modeled in freespace. Table 4 shows the highlights of the research that are inneither tissue layers nor air.

Conflicts of Interest

The authors declare that there is no conflict of interestregarding the publication of this paper.

Acknowledgments

This work was supported by the Electrical EngineeringDepartment of University of North Dakota, the NorthDakota Department of Commerce, and the Applied ScienceUniversity in Jordan.

References

[1] J. S. Ho, S. Kim, and A. S. Y. Poon, “Midfield wireless poweringfor implantable systems,” Proceedings of the IEEE, vol. 101,no. 6, pp. 1369–1378, 2013.

[2] M. Soma, D. C. Galbraith, and R. L. White, “Radio-frequencycoils in implantable devices: misalignment analysis and designprocedure,” IEEE Transactions on Biomedical Engineering,vol. BME-34, no. 4, pp. 276–282, 1987.

[3] “The life and time of Nicola Tesla,” http://www.comp.dit.ie/dgordon/Research/MScArtefacts/Tesla/TeslaBook.pdf.

[4] C. Liu, Y. Guo, and S. Xiao, “A review of implantable antennasfor wireless biomedical devices,” Forum for ElectromagneticResearch Methods and Application Technologies (FERMAT),vol. 14, 2016.

[5] T. Sun, X. Xie, and Z. Wang,Wireless Power Transfer for Med-ical Microsystems, Springer, New York, NY, USA, 2013.

[6] L. Baby and S. S. Banu, “A survey on wire free powertransmission in biomedical implants,” International Journal

of Advanced Research in Electrical Electronics and Instru-mentation Engineering, vol. 5, no. 5, pp. 3543–3546, 2016.

[7] J. C. Schuder, “Powering an artificial heart: birth of the induc-tively coupled-radio frequency system in 1960,” ArtificialOrgans, vol. 26, no. 11, pp. 909–915, 2002.

[8] F. C. Flack, E. D. James, and D. M. Schlapp, “Mutual induc-tance of air-cored coils: effect on design of radio-frequencycoupled implants,” Medical and Biological Engineering, vol. 9,no. 2, pp. 79–85, 1971.

[9] J. C. Schuder, J. H. Gold, and H. E. Stephenson, “An induc-tively coupled RF system for the transmission of 1 kW ofpower through the skin,” IEEE Transactions on BiomedicalEngineering, vol. BME-18, no. 4, pp. 265–273, 1971.

[10] W. H. Ko, S. P. Liang, and C. D. F. Fung, “Design of radio-frequency powered coils for implant instruments,” Medicaland Biological Engineering and Computing, vol. 15, no. 6,pp. 634–640, 1977.

[11] N. d. N. Donaldson and T. A. Perkins, “Analysis of resonantcoupled coils in the design of radio frequency transcutaneouslinks,” Medical and Biological Engineering and Computing,vol. 21, no. 5, pp. 612–627, 1983.

[12] J. A. Von Arx and K. Najafi, “A wireless single-chip telemetry-powered neural stimulation system,” in 1999 IEEE Interna-tional Solid-State Circuits Conference. Digest of TechnicalPapers. ISSCC. First Edition (Cat. No.99CH36278), pp. 214-215, San Francisco, CA, USA, 1999.

[13] W. J. Heetderks, “RF powering of millimeter- andsubmillimeter-sized neural prosthetic implants,” IEEE Trans-actions on Biomedical Engineering, vol. 35, no. 5, pp. 323–327, 1988.

[14] C. M. Zierhofer and E. S. Hochmair, “High-efficiencycoupling-insensitive transcutaneous power and data transmis-sion via an inductive link,” IEEE Transactions on BiomedicalEngineering, vol. 37, no. 7, pp. 716–722, 1990.

[15] K. Van Schuylenbergh and R. Puers, “Self tuning inductivepowering for implantable telemetric monitoring systems,” inSolid-State Sensors and Actuators, 1995 and Eurosensors IX.Transducers '95. The 8th International Conference on, vol. 1,pp. 1–7, Stockholm, Sweden, 1995.

[16] T. Akin, K. Najafi, and R. M. Bradley, “A wireless implantablemultichannel digital neural recording system for a microma-chined sieve electrode,” IEEE Journal of Solid-State Circuits,vol. 33, no. 1, pp. 109–118, 1998.

[17] J. Dai and D. C. Ludois, “A survey of wireless power transferand a critical comparison of inductive and capacitive couplingfor small gap applications,” IEEE Transactions on Power Elec-tronics, vol. 30, no. 11, pp. 6017–6029, 2015.

[18] G. A. Covic and J. T. Boys, “Inductive power transfer,” Pro-ceedings of the IEEE, vol. 101, no. 6, pp. 1276–1289, 2013.

[19] U. M. Jow and M. Ghovanloo, “Design and optimization ofprinted spiral coils for efficient transcutaneous inductivepower transmission,” IEEE Transactions on Biomedical Cir-cuits and Systems, vol. 1, no. 3, pp. 193–202, 2007.

[20] A. K. Ramrakhyani, S. Mirabbasi, and M. Chiao, “Design andoptimization of resonance-based efficient wireless power deliv-ery systems for biomedical implants,” IEEE Transactions onBiomedical Circuits and Systems, vol. 5, no. 1, pp. 48–63, 2011.

[21] R. F. Xue, K. W. Cheng, and M. Je, “High-efficiency wirelesspower transfer for biomedical implants by optimal resonantload transformation,” IEEE Transactions on Circuits and Sys-tems I: Regular Papers, vol. 60, no. 4, pp. 867–874, 2013.


http://www.comp.dit.ie/dgordon/Research/MScArtefacts/Tesla/TeslaBook.pdf

http://www.comp.dit.ie/dgordon/Research/MScArtefacts/Tesla/TeslaBook.pdf

[22] M. Yin and M. Ghovanloo, “A flexible clockless 32-ch simul-taneous wireless neural recording system with adjustableresolution,” in 2009 IEEE International Solid-State CircuitsConference - Digest of Technical Papers, pp. 432–434, SanFrancisco, CA, USA, 2009.

[23] S. Mutashar, M. Hannan, S. Samad, and A. Hussain, “Analysisand optimization of spiral circular inductive coupling link forbio-implanted applications on air and within human tissue,”Sensors, vol. 14, no. 7, pp. 11522–11541, 2014.

[24] R. R. Harrison, “Designing efficient inductive power links forimplantable devices,” in 2007 IEEE International Symposiumon Circuits and Systems, pp. 2080–2083, New Orleans, LA,USA, 2007.

[25] R. Carta, J. Thoné, G. Gosset, G. Cogels, D. Flandre, andR. Puers, “A self-tuning inductive powering system for bio-medical implants,” Procedia Engineering, vol. 25, pp. 1585–1588, 2011.

[26] R. Carta, N. Pateromichelakis, J. Thoné, M. Sfakiotakis, D. P.Tsakiris, and R. Puers, “A wireless powering system for avibratory-actuated endoscopic capsule,” Procedia Engineering,vol. 5, pp. 572–575, 2010.

[27] INTECH, Wireless Telemetry for Implantable BiomedicalMicrosystems, http://www.kntu.ac.ir/DorsaPax/userfiles/file/Electrical/az-icas/20120716090651608.pdf.

[28] K. Bocan and E. Sejdić, “Adaptive transcutaneous power trans-fer to implantable devices: a state of the art review,” Sensors,vol. 16, no. 3, p. 393, 2016.

[29] A. Sharma, E. Kampianakis, and M. S. Reynolds, “A dual-bandHF and UHF antenna system for implanted neural recordingand stimulation devices,” IEEE Antennas and Wireless Propa-gation Letters, vol. 16, pp. 493–496, 2017.

[30] O. Knecht, R. Bosshard, and J. W. Kolar, “High-efficiencytranscutaneous energy transfer for implantable mechanicalheart support systems,” IEEE Transactions on Power Electron-ics, vol. 30, no. 11, pp. 6221–6236, 2015.

[31] O. Knecht, R. Bosshard, J. W. Kolar, and C. T. Starck, “Optimi-zation of transcutaneous energy transfer coils for high powermedical applications,” in 2014 IEEE 15th Workshop on Controland Modeling for Power Electronics (COMPEL), pp. 6221–6236, Santander, Spain, 2014.

[32] D. Ahn and M. Ghovanloo, “Optimal design of wireless powertransmission links for millimeter-sized biomedical implants,”IEEE Transactions on Biomedical Circuits and Systems,vol. 10, no. 1, pp. 125–137, 2016.

[33] D. Ahn and S. Hong, “Wireless power transmission withself-regulated output voltage for biomedical implant,” IEEETransactions on Industrial Electronics, vol. 61, no. 5,pp. 2225–2235, 2014.

[34] M. Zargham and P. G. Gulak, “A 0.13μm CMOS inte-grated wireless power receiver for biomedical applications,”in 2013 Proceedings of the ESSCIRC (ESSCIRC), pp. 137–140, Bucharest, Romania, 2013.

[35] M. Zargham and P. G. Gulak, “Maximum achievable efficiencyin near-field coupled power-transfer systems,” IEEE Transac-tions on Biomedical Circuits and Systems, vol. 6, no. 3,pp. 228–245, 2012.

[36] R. Wu, S. Raju, M. Chan, J. K. O. Sin, and C. P. Yue, “Silicon-embedded receiving coil for high-efficiency wireless powertransfer to implantable biomedical ICs,” IEEE Electron DeviceLetters, vol. 34, no. 1, pp. 9–11, 2013.

[37] R. Wu, S. Raju, M. Chan, J. K. O. Sin, and C. P. Yue, “Wirelesspower link design using silicon-embedded inductors for brain-machine interface,” in Proceedings of Technical Program of2012 VLSI Design, Automation and Test, pp. 1–4, Hsinchu,Taiwan, 2012.

[38] U.-M. Jow and M. Ghovanloo, “Modeling and optimization ofprinted spiral coils in air, saline, and muscle tissue environ-ments,” IEEE Transactions on Biomedical Circuits andSystems, vol. 3, no. 5, pp. 339–347, 2009.

[39] M.W. Baker and R. Sarpeshkar, “Feedback analysis and designof RF power links for low-power bionic systems,” IEEETransactions on Biomedical Circuits and Systems, vol. 1,no. 1, pp. 28–38, 2007.

[40] G. A. Kendir, Wentai Liu, Guoxing Wang et al., “An optimaldesign methodology for inductive power link with class-Eamplifier,” IEEE Transactions on Circuits and Systems IRegular Papers, vol. 52, no. 5, pp. 857–866, 2005.

[41] G. Wang, W. Liu, M. Sivaprakasam, and G. A. Kendir, “Designand analysis of an adaptive transcutaneous power telemetryfor biomedical implants,” IEEE Transactions on Circuits andSystems I Regular Papers, vol. 52, no. 10, pp. 2109–2117, 2005.

[42] M. Catrysse, B. Hermans, and R. Puers, “An inductive powersystem with integrated bi-directional data-transmission,”Sensors and Actuators A: Physical, vol. 115, no. 2-3, pp. 221–229, 2004.

[43] M. A. Adeeb, A. B. Islam, M. R. Haider, F. S. Tulip, M. N.Ericson, and S. K. Islam, “An inductive link-based wirelesspower transfer system for biomedical applications,” Activeand Passive Electronic Components, vol. 2012, Article ID879294, 11 pages, 2012.

[44] M. Kiani, K. Y. Kwon, F. Zhang, K. Oweiss, andM. Ghovanloo,“Evaluation of a closed loop inductive power transmission sys-tem on an awake behaving animal subject,” in 2011 AnnualInternational Conference of the IEEE Engineering in Medicineand Biology Society, pp. 7658–7661, Boston, MA, USA, 2011.

[45] M. Kiani, Uei-Ming Jow, and M. Ghovanloo, “Design andoptimization of a 3-coil inductive link for efficient wirelesspower transmission,” IEEE Transactions on BiomedicalCircuits and Systems, vol. 5, no. 6, pp. 579–591, 2011.

[46] A. Laskovski and M. Yuce, “Class-E oscillators as wirelesspower transmitters for biomedical implants,” in 2010 3rdInternational Symposium on Applied Sciences in Biomedicaland Communication Technologies (ISABEL 2010), pp. 1–5,Roma, Italy, 2010.

[47] A. Laskovski, M. Yuce, and T. Dissanayake, “Stacked spiralsfor use in biomedical implants,” in 2009 Asia Pacific Micro-wave Conference, pp. 389–392, Singapore, Singapore, 2009.

[48] M. Kiani and M. Ghovanloo, “An RFID-based closed-loopwireless power transmission system for biomedical applica-tions,” IEEE Transactions on Circuits and Systems II: ExpressBriefs, vol. 57, no. 4, pp. 260–264, 2010.

[49] U.-M. Jow and M. Ghovanloo, “Optimization of data coils in amultiband wireless link for neuroprosthetic implantabledevices,” IEEE Transactions on Biomedical Circuits andSystems, vol. 4, no. 5, pp. 301–310, 2010.

[50] M. Ghovanloo and S. Atluri, “A wide-band power-efficientinductive wireless link for implantable microelectronic devicesusing multiple carriers,” IEEE Transactions on Circuits andSystems I: Regular Papers, vol. 54, no. 10, pp. 2211–2221, 2007.

[51] C. M. Zierhofer and E. S. Hochmair, “Geometric approach forcoupling enhancement of magnetically coupled coils,” IEEE


http://www.kntu.ac.ir/DorsaPax/userfiles/file/Electrical/az-icas/20120716090651608.pdf

http://www.kntu.ac.ir/DorsaPax/userfiles/file/Electrical/az-icas/20120716090651608.pdf

Transactions on Biomedical Engineering, vol. 43, no. 7,pp. 708–714, 1996.

[52] A. Ghahary and B. H. Cho, “Design of transcutaneous energytransmission system using a series resonant converter,” IEEETransactions on Power Electronics, vol. 7, no. 2, pp. 261–269,1992.

[53] G. B. Joun and B. H. Cho, “An energy transmission systemfor an artificial heart using leakage inductance compensationof transcutaneous transformer,” IEEE Transactions on PowerElectronics, vol. 13, no. 6, pp. 1013–1022, 1998.

[54] E. S. Hochmair, “System optimization for improved accuracyin transcutaneous signal and power transmission,” IEEETransactions on Biomedical Engineering, vol. BME-31, no. 2,pp. 177–186, 1984.

[55] A. Ghahary, Design of Transctaneous Energy TransmissionSystem Using Series Resonant Converter, Univ. VerginiaPower Electronic Center, 1989.

[56] T. Sun, X. Xie, G. Li, Y. Gu, Y. Deng, and Z. Wang, “A two-hopwireless power transfer system with an efficiency-enhancedpower receiver for motion-free capsule endoscopy inspection,”IEEE Transactions on Biomedical Engineering, vol. 59, no. 11,pp. 3247–3254, 2012.

[57] M. Ryu, J. D. Kim, H. U. Chin, J. Kim, and S. Y. Song,“Three-dimensional power receiver for in vivo roboticcapsules,” Medical & Biological Engineering & Computing,vol. 45, no. 10, pp. 997–1002, 2007.

[58] A. Kurs, A. Karalis, R. Moffatt, J. D. Joannopoulos, P. Fisher,and M. Soljacic, “Wireless power transfer via strongly coupledmagnetic resonances,” Science, vol. 317, no. 5834, pp. 83–86,2007.


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a literature survey on wireless power transfer for biomedical...

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