Testing Wireless Medical Devices

Greg Kiemel

Outline Wireless Trends Latest News Medical Wireless Technologies Risks Regulatory Standards Beyond EMC Compliance Considerations

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Wireless Trends

Increasing Rate of Change

It took more than 90 years for landline service to reach 100 million consumers

More than 21 years for color televisions to reach 100 million consumers

But less than 17 years for wireless to reach 100 million consumers.

Source: CTIA – The Wireless Association, Wireless Quick Facts, 2011. 4

Regulatory Approval Trends Virtually all radios sold in the U.S. require FCC

certification. To keep up with the increasing number of

applications, the FCC created the Telecommunications Certification Body (TCB) program in June 2000.

TCBs certify wireless products under the authority of the FCC.

FCC ET Docket 13-44 released 12/30/14 made TCBs the only route to certification. The FCC will no longer accept applications for certification. 5

TCB Application Trend

Source: https://apps.fcc.gov/oetcf/eas/reports/GenericSearch.cfm

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10000

20000

30000

40000

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Ap

pro

vals

Year

FCC

TCB

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Application TrendsJan 1, 2014 – Dec 31, 2014

TCBs issued 42,669 Approvals, FCC 425

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Wireless Data StandardsUsable Range WWAN

802.16e (WiMax)

GSM, GPRS, Edge, HSPA

4G LTE

WLAN802.11a/b/g/n

WPAN 802.11ac

802.15.4 (Zigbee)

802.15.1 (Bluetooth)

Feet

Miles

802.15.3 (UWB)

WBAN802.15.6 MBAN

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MedRadio Inductive Telemetry

802.11ad

Evolution of Applications / Platforms

Computer

TV, Video

Wireless Telecommunications

Internet

Convergence of Technologies

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Medical

Multiple Radios in the Same Host Device

Patient Monitor with Wi-Fi, Bluetooth, and WWAN Radios

4G Cellphone with Wi-Fi, Bluetooth, NFC, and GPS

Notebook PC or Tablet with Cellular modem, Wi-Fi, and Bluetooth

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New Technologies Spectrum Efficiency is the driving force…more users

require more throughput while occupying the same finite chunk of frequency spectrum

Biggest Breakthroughs– Smart Antenna Systems

• MIMO (Multiple Input and Multiple Output)• Adaptive Beam forming

– OFDM (Orthogonal frequency-division multiplexing)– Cognitive Radio

• Listen Before Talk (LBT)• Dynamic Frequency Selection (DFS)• Adaptive Frequency Hopping (e.g. Bluetooth devices)

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The ‘New’ Wireless Medical World

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Wireless Proliferation into MedicalWhy?

– Convenience: don’t want to go to the doctor

– Speed: want and need fast service– Separation: can keep people or

equipment out of the sterile environment

– Appearance: nobody wants to look sick being hooked up to wires or tubes

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Wireless Proliferation into Medical

Where - Point of care

– Hospital – Clinic – Home– Mobile

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Latest News

FCC Report and Order (FCC 14-208) FCC will no longer accept applications for certification. All grants will be

issued by TCBs. The Permit But Ask procedure will be codified. Clarification of TCB responsibilities for performing market surveillance. Specify steps for addressing instances of deficient TCB performance,

including sanctions and rescinding TCB authority. Modify the rules to reference new standards (ISO/IEC 17065) used to accredit

TCBs Require labs that test for certification or DoC to be accredited. [“Testing

laboratories located in non MRA countries are not FCC recognized as accredited under the current procedures.“]

Codify a procedure through which the Commission currently recognizes new laboratory accreditation bodies;

Update references to industry measurement procedures in the Commission’s rules (e.g. ANSI C63.4-2014 and ANSI C63.10-2013); and

Provide greater flexibility to enable the FCC’s OET to address minor technical issues that may be raised when updating to the latest versions of industry standards that are referenced in Parts 2, 5, 15, and 18 of the Commission’s rules.

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FCC Report and Order (FCC 14-30)

New rules for U-NII devices (e.g. 802.11an) became effective on June 2, 2014. Transition period, see FCC KDB 926956:

– New devices can be approved until June 1, 2015 under either the old or new rules.– Starting June 2, 2015, new approvals must be to the new rules. – Starting June 2, 2016, permissive changes must be to the new rules. Also products previously

certified under the old rules can’t be marketed unless they meet the new rules (C2PC application required).

Indoor-only restriction removed from the 5.2 GHz band. Also increased the output power in that band.

Extended the upper frequency edge of the 5.8 GHz band to match FCC 15.247. They are now both 5725 – 5850 MHz

Harmonized the rules between 15.247 and 15.407 for DTS device operating in the 5.8 GHz band.

U-NII device software must be secured to prevent its modification New DFS radar waveform and new test requirements.

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Radio Equipment Directive (RED) 2014/53/EU

Published in the OJEU on April 16, 2014 will be applicable June 13, 2016. No one can claim compliance with this new directive until then.

However, if equipment meets the requirements of the R&TTE Directive before June 13, 2016, compliance with the RED is not mandatory until June 13, 2017. For new equipment placed on the EU market after June 12, 2016 must meet the requirements of the RED.

Sound and TV broadcast receivers will be included in the RED Telecom Terminal Equipment will be excluded “Radio determination” will be included, e.g. RFID, movement detection. Radio equipment operating below 9 kHz will be included ISM equipment (generates RF to perform work, not telecommunications) will

be excluded. Role of a Notified Body is still to assess compliance at the request of the

manufacturer. This is optional if harmonized standards have been applied in full. Notified Bodies will issue an “EU-Type Examination Certificate” that documents their assessment of the manufacturer’s supplied “Technical Documentation” (see Annex V of the RED)

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Changes to EN 300 328 and EN 301 893 EN 300 328 V1.8.1 and EN 301 893 V1.7.1 required starting Jan 1, 2015. Even products that have been selling for years under the previous version

must now meet the latest version if they are still being shipped into the EU. Products already in the EU prior to Jan 1, 2015 do NOT need to be recalled or

retested. The main differences between the old and new versions of the standards are

significant and can be summarized as follows:– Adequate spectrum sharing. The efficiency of the various sharing mechanisms

must be tested per the procedures of the harmonized standards. Previous versions permitted just an attestation from the manufacturer.

– An output power test methodology that would address a wide-range of technologies. This new approach is completely different from what was included in V1.7.1 of the standard.

– A power spectral density test methodology that would permit a higher output power. Many devices are not limited by the 100mW EIRP limit, but instead by the 10mW/MHz power spectral density (PSD) limit. EN 300 328 V1.8.1 has very different and much more complex method of measuring power spectral density.

– Harmonize test methods with other ETSI standards operating in the same bands.

EN 300 328 V1.9.1 published in the OJ on April 17, 2015. Mandatory starting Nov. 30, 2016. Contains minor fixes to previous version.

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Medical Wireless Technology

Medical Wireless Technology

Wearable, wireless devices capable of offering real time data– 2012 – 14 million – 2016 – 171 million (estimated)

• $6 billion market minimum

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DIGI FIT LIFE, “Wearble, Wireless Technology to Generate Minimum $6 Billion by 2016”, August 2012, retrieved from http://digifitlife.com/wearable-wireless-technology-to-generate-minimum-6-billion-by-2016/#.VL_xwkfF-So

Medical Wireless Technology• Inductive

• Typically below 200 kHz• Very short range, low level• Inductive charging

• ISM/SRD (Industrial, Scientific & Medical / Short range Devices)• Frequencies – 13.56 MHz (ISM/SRD), 27.12 MHz (ISM), 40.68 MHz

(ISM), 433.92 MHz (ISM), 865.0 MHz (SRD), 915.0 MHz (ISM), 2450 MHz (ISM, SRD) , 5.8 GHz (ISM, SRD)

• Crowded• Medical Device Radiocommunication Service (MedRadio) or

MICS (Medical Implant Communication Service) • 401-406 MHz • Special – implanted devices• Short range - approximately 3-5meters

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Medical Wireless Technology• A Sub-set of MedRadio , the FCC also permits

operation of Medical Micropower Network (MMN) devices• In November 2011, the FCC adopted rules for the operation

of ultra-low power wideband networks in the 413-419 MHz, 426-432 MHz, 438-444 MHz, 451-457 MHz, and 2360-2400 MHz bands: http://www.fcc.gov/document/medical-micro-power-networks

• MMN’s are used to restore functions to paralyzed limbs.• Implanted transmitters in the body take the place of

damaged nerves, restoring sensation and mobility.• Multiple MMNs may be present within a patient. Implants

may only communicate with the programmer /controller for their MMN, and not with each other.

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Medical Wireless Technology MBAN (Medical Body Area Networks)

• 5/2012 - FCC Designates 2360-2400 MHz band• ‘License-by-rule’ – users will not have to apply for/receive

individual station licenses• Sharing 2360-2390 w/Aeronautical Mobile Telemetry (AMT)

licenses. Use in that band restricted to indoor health care facilities & requires registration w/MBAN coordinator. FCC still needs to select.

• Rest of band no registration, use anywhere (mobile, home, health care facilities)

• Low power, short range– http://www.fcc.gov/document/medical-body-area-networks-first-report-and-

order/ 24

Medical Wireless Technology MBAN (Medical Body Area Networks)

• Multiple body sensors for monitoring & control• ‘Facebook for your organs’ • removes the tether

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Medical Wireless Technology WMTS (Wireless Medical Telemetry

Service – instituted in 2000)– Freqs: 608-614 MHz, 1395-1400 MHz,

1429-1432 MHz– Long range– Safe band, proprietary, very common use

for wireless patient monitoring– Limited to use within health care facilities.

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Wireless Technology Wi-Fi – connectivity of monitors

– 92% Wi-Fi penetration into large (500+ employees) healthcare facilities now & 100% by 2016

– 17% of the world’s population uses Wi-Fi– Wi-Fi Alliance working on WLAN best

practices & Risk Mgmnt, plus personal home healthcare architecture

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Wireless Technology Bluetooth – low power, secure, interoperability

– 2 billion BT products ship in 2012– Bluetooth 4.0 is capable of Basic Rate and Enhance Data Rate

operation (BR/ EDR) as well as Low Energy (LE), or LE only. – Bluetooth BR and EDR modes operate on 79 hopping channels

that are tested at: 2402, 2441, and 2480 MHz– Bluetooth LE Advertising mode utilizes only three

channels: 2402, 2426, and 2480 MHz– Bluetooth LE Data mode has 37 hopping channels: 2404, 2442,

and 2478 MHz

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Wireless Technology RFID – equipment or people tags Zigbee – some but mostly industrial

devices Cell bands – mobile communication/

apps

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Risks

Are Wireless Medical Devices Safe and Effective? Interference could result in injury or death Failure to provide critical status or drug injection

information Problem Reports (FDA)

– Feb 2006 – cell phone interfered w/infusion pump causing higher prescribed rate

– June 2006 – cell phone caused infusion pump to stop– Sept 2008 – electrocautery device caused a loss of therapeutic effect

on an implant– Other studies – ICD reactions to RFID

Legal Perspectivehttp://www.fr.com/files/uploads/attachments/FinalRegulatoryWhitePaperWirelessMedicalTechnologies.pdf 31

RF Wireless Coexistence Due to the increasing number of wireless devices, the

risk of interference with wireless medical devices is also increasing

Critical data transmitted by medical devices could be delayed or blocked by other nearby wireless devices.

Current EMC standards are inadequate. In-band interference is specifically excluded. Manufacturers cannot claim the safe operation of their wireless medical device based solely on EMC test results.

Test methods are under development to assess the risk of interference. (ANSI, Univ of Oklahoma)

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Current Guidance on Coexistence Co-existence is discussed in the FDA Guidance for Wireless

Technology in Medical Devices. Draft issued Jan 2007, became formal guidance August 2013. http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm077210.htm

– Also contains guidance on risk management, design & development, verification, validation, labeling, etc.

Environmental Considerations – Radio Channel Characteristics, Polarization, Co-channel & Adjacent Channel Interference, Distance from the interfering source– Testing should be done in both an anechoic chamber and in

situ, with each wireless medical device separately exposed to one or more wireless networks.

http://www.medicalelectronicsdesign.com/article/wireless-medical-device-coexistence

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Regulatory

Regulatory US

– FDA – Medical• Regulates all medical devices & general public health and

safety• http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/Guidanc

eDocuments/ucm077210.htm

– FCC – Wireless and RF Exposure• Spectrum management• Standards• TCB route for approvals – short turnaround

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Regulatory EU

– Medical & Wireless - Directives • Radio (RTTE) / EMC (EMCD)

– RTTE repealed and RED begins June 13, 2016– Old EMCD repealed and New EMCD begins April 20,

2016

• Medical Devices (MDD, AIMDD)• Safety (Electrical, Mechanical, RF)• Self declaration

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Typical Wireless Test Requirements

Output Power Effective Radiated Power Frequency Stability Occupied Bandwidth Emissions Mask Power Spectral Density Spurious Emissions Immunity

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Effective Radiated Power –MedRadio 403 – 405 MHz

Maximum EIRP: 25uW = 85.2 dBuV/m @ 3 meters measured over reference ground plane.

Implants must be configured to transmit in a human torso simulator placed 1.5 m above the ground plane.– Dimensions of the fixture, and the properties of the

tissue substitute material are defined in 95.639(f)(2).– The properties of the tissue substitute material should

be verified on the day of test, and the temperature of the material recorded at the start and conclusion of the test.

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Torso Simulator Cylindrical Plexiglas container with

a size of 30 cm by 76 cm with a sidewall thickness of 0.635 cm.

A mounting grid for the implant and associated leads must be provided inside the container that permits the implant to be positioned vertically and horizontally

The implant must be mounted 6 cm from the sidewall and centered vertically within the container.

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Radiated Emissions Test Setup

EUT Horizontal

EUT Vertical

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Radiated Emissions Test Setup

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Tissue Substitute Material Torso simulator must be completely filled with a tissue

substitute material whose dielectric and conductivity properties match those of human muscle tissue at 403.5 MHz

Simple saline solutions do not meet the above criteria. A formula for a suitable tissue substitute material is defined in the paper “Simulated Biological Materials for Electromagnetic Radiation Absorption Studies” by G. Hartsgrove, A. Kraszewski, and A. Surowiec as published in “Bioelectromagnetics 8:29–36 (1987)”.

All emissions measurements are made with the tissue material at a nominal temperature of 20–25°C

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Standards

Standards Inductive (communications)

– US• FCC Part 15.209 / 207 (tested in air)

– EU• ERC/REC 70-03• ETSI EN 302 195-2 / -1 (tested in saline)• ETSI EN 301 489-31 / -1

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Standards Inductive (charging portion only)

– US• FCC Part 18• RF Exposure (KDB 680106)

– EU• CISPR 11• IEC 60601-1-2

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Standards ISM/SRD

– US• 15.209 / 15.109 / 15.107• 15.247 – 2.4 - 2.4835 GHz Band• 15.249 – 902-928 MHz

– EU• ERC/REC 70-03• EN ETSI 300 220-2/-1 / 300 440 /300 328• EN ETS 301 489-3 / -1

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Standards MedRadio/MICS

– US• Part 95I / 2 • 15.109 / 107

– EU• ERC/REC 70-03• EN ETSI 301 839-2 / -1• EN ETS 301 489-27 / -1

– Other• Torso simulator 47

Standards MBAN

– US• Part 95I

– EU• ERC/REC 70-03• Unknown – we are to assume Part of MICS but

could also be Wi-Fi stds or some combo • EN ETSI 301 839-2 / -1• EN ETS 301 489-27 / -1

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Standards Wi-Fi/BT

– US• Part 15.407 / 15.247 • 15.207

– EU• ERC/REC 70-03• EN ETSI 300 328• EN ETS 301 489-17 / -1

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Medical Device Standards FDA

– IEC 601-1-2 – EMC of medical electrical equipment & systems

• IEC 60601-2-X – specific types of equipment– FDA Guidance

• Higher immunity levels might be required & have been requested

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Medical Device Standards Other

– AAMI PC69 – EMC for Active Implantable Medical Devices

– EN 45502-2 (Active Implantable Medical Devices)– ISO 14708-2 (implantable cardiac pacemakers)– EN & ETSI reqs– ISO Standards (wheelchairs, pulse oximeters,

neurostimulators)

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Beyond EMC

Special Requirements – RF Exposure / RF Safety

RF Exposure is the effect of emissions from transmitters on the quality of the human environment.

On August 1, 1996, the Commission adopted the NCRP's recommended Maximum Permissible Exposure limits for field strength and power density for the transmitters operating at frequencies of 300 kHz to 100 GHz.

FCC and Industry Canada adopted the specific absorption rate (SAR) limits for devices operating within close proximity to the body as specified within the ANSI/IEEE C95.1-1992 guidelines.

More info: http://transition.fcc.gov/oet/rfsafety/

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Exposure Categories

Fixed Mobile Portable

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Exposure Limits FCC RF exposure limits are based on ANSI/IEEE C95.1-1992 and NCRP

Report No. 86, but not identical to these standards Maximum Permissible Exposure (MPE) limits are applicable to fixed and

mobile transmitters. Used >= 20cm from the head or torso– Frequency dependent free-space power density and/or field strength

limits– Based on whole-body averaged plane wave equivalent exposure

conditions Specific Absorption Rate (SAR) are applicable to portable transmitters.

Used < 20cm from the head or torso– One gram averaged energy absorption limits for the US and Canada,

10g limits for the rest of the world– Based on partial-body or localized near-field exposure conditions

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Specific Absorption Rate (SAR)

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SAR Test System

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SAR Test SystemRadio Held Underneath Body Phantom

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SAR Test SystemRadio Held Next to Head Phantom

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RF Exposure Requirement for MedRadio Implants

95.1221 RF exposure: “… Applications for equipment authorization of devices operating under this section must demonstrate compliance with these requirements using either finite difference time domain (FDTD) computational modeling or laboratory measurement techniques.”

FCC KDB 447498 D01 v05v401, Section 4.2.4: “When the aggregate of the maximum power available at the antenna port and radiating structures of an implanted transmitter, under all operating circumstances, is ≤ 1.0 mW, SAR test exclusion may be applied.” 60

Special Requirements – Listen Before Talk (LBT)

Required for MedRadio operation in the 401 –406 MHz band.– EN 301 839-1 Clause 10 – best test procedure

Except in the case of a Medical Implant Event, communications sessions shall be initiated via LBT (either by programmer or implant). Before a communications session is initiated the requirements as stated specifically in clauses 10.1-10.6 of EN 301 839-1 shall be met.

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Compliance Considerations

Research Objectives for your Target Market Spectrum Allocation

– Frequency Bands– Output power– Data vs. Voice– Modulation type– Licensed vs. Unlicensed

Specifications and Test Methods– EMC and RF Safety

Equipment Authorization process– System or modular approval– Self Declaration or submittal to spectrum authority– Labeling and User Info 63

Write a Test Plan

IEC 60601-1-2, 4th edition "Prior to the start of formal testing, a detailed test plan shall be provided to the test laboratory.“ Compliance Objective – Certification, Class II permissive change, or

audit. Target markets – U.S., Canada, EU, etc. Brief product description List of standards including version and year. Any applicable interpretations or procedures from spectrum

authorities. Complete List of operating modes including modulation types, data

rates, power levels, and antennas. Detailed equipment configuration for each test Operating instructions

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Make EMC a Design Consideration

The focus of EMC design: grounding, filtering, component selection, PCB layout, and shielding. Single solutions don’t exist; but rather a

combination of suppression techniques are required. Don’t wait until the end of the design cycle to test. “One test result is worth one thousand expert

opinions” – Wernher Von Braun

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Common Design Pitfalls Poor antenna matching Lack of shielding Design objectives or omissions that

conflict with regulatory requirements– Output power versus operating band– RF Exposure– Listen Before Talk, Duty Cycle, or Dynamic

Frequency Selection (DFS) 66

Get Expert Testing & Approval Services Partner with a domestic EMC laboratory that is accredited for

foreign specifications– Permits testing in-country to obtain global approvals. For

example Japan and Korea wireless can be tested locally.– Easy access to someone who is familiar with the

requirements of your target market Confirm that your EMC laboratory has experience in medical

EMC– How many MICS, MedRadio, WMTS, Wi-Fi, and

Bluetooth grants have they issued? Ask if your EMC laboratory is equipped for the latest medical

EMC test requirements– Radiated Immunity to 6 GHz, 10V/m with uniform field– Radiated Immunity in the 4th edition "IMMUNITY to proximity

fields from RF wireless communications"– Radiated Emissions testing at 10 meters

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Thank You!

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