Testing Wireless Medical Devices. Greg Kiemel

Transcription

1 Testing Wireless Medical Devices Greg Kiemel

2 Outline Wireless Trends Latest News Medical Wireless Technologies Risks Regulatory Standards Beyond EMC Compliance Considerations 2

3 Wireless Trends

4 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,

5 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 TCBs certify wireless products under the authority of the FCC. FCC ET Docket released 12/30/14 made TCBs the only route to certification. The FCC will no longer accept applications for certification. 5

6 TCB Application Trend Approvals Year FCC TCB 6 Source:

7 Application Trends Jan 1, 2014 Dec 31, 2014 TCBs issued 42,669 Approvals, FCC 425 7

8 Wireless Data Standards Usable Range Miles Feet GSM, GPRS, Edge, HSPA ad (Bluetooth) WWAN 4G LTE WLAN a/b/g/n WPAN (UWB) WBAN MBAN MedRadio Inductive Telemetry (Zigbee) e (WiMax) ac 8

9 Evolution of Applications / Platforms TV, Video Computer Convergence of Technologies Medical Wireless Telecommunications Internet 9

10 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 10

11 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) 11

12 The New Wireless Medical World 12

13 Wireless Proliferation into Medical Why? 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 13

14 Wireless Proliferation into Medical Where - Point of care Hospital Clinic Home Mobile 14

15 Latest News

16 FCC Report and Order (FCC ) 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 C and ANSI C ); 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 16 standards that are referenced in Parts 2, 5, 15, and 18 of the Commission s rules.

17 FCC Report and Order (FCC 14-30) New rules for U-NII devices (e.g an) became effective on June 2, Transition period, see FCC KDB : 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 They are now both MHz Harmonized the rules between and 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. 17

18 Radio Equipment Directive (RED) 2014/53/EU Published in the OJEU on April 16, 2014 will be applicable June 13, 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, 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) 18

19 Changes to EN and EN EN V1.8.1 and EN V1.7.1 required starting Jan 1, 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 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 V1.9.1 published in the OJ on April 17, Mandatory starting Nov. 30, Contains minor fixes to previous version. 19

20 Medical Wireless Technology

21 Medical Wireless Technology Wearable, wireless devices capable of offering real time data million million (estimated) $6 billion market minimum 21 DIGI FIT LIFE, Wearble, Wireless Technology to Generate Minimum $6 Billion by 2016, August 2012, retrieved from

22 Medical Wireless Technology Inductive Typically below 200 khz Very short range, low level Inductive charging ISM/SRD (Industrial, Scientific & Medical / Short range Devices) Frequencies MHz (ISM/SRD), MHz (ISM), MHz (ISM), MHz (ISM), MHz (SRD), MHz (ISM), 2450 MHz (ISM, SRD), 5.8 GHz (ISM, SRD) Crowded Medical Device Radiocommunication Service (MedRadio) or MICS (Medical Implant Communication Service) MHz Special implanted devices Short range - approximately 3-5meters 22

23 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 MHz, MHz, MHz, MHz, and MHz bands: 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. 23

24 Medical Wireless Technology MBAN (Medical Body Area Networks) 5/ FCC Designates MHz band License-by-rule users will not have to apply for/receive individual station licenses Sharing 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 24

25 Medical Wireless Technology MBAN (Medical Body Area Networks) Multiple body sensors for monitoring & control Facebook for your organs removes the tether 25

26 Medical Wireless Technology WMTS (Wireless Medical Telemetry Service instituted in 2000) Freqs: MHz, MHz, MHz Long range Safe band, proprietary, very common use for wireless patient monitoring Limited to use within health care facilities. 26

27 Wireless Technology Wi-Fi connectivity of monitors 92% Wi-Fi penetration into large (500+ employees) healthcare facilities now & 100% by % of the world s population uses Wi-Fi Wi-Fi Alliance working on WLAN best practices & Risk Mgmnt, plus personal home healthcare architecture 27

28 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 28

29 Wireless Technology RFID equipment or people tags Zigbee some but mostly industrial devices Cell bands mobile communication/ apps 29

30 Risks

31 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 Perspective 31

32 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) 32

33 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 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. 33

34 Regulatory

35 US FDA Medical Regulatory Regulates all medical devices & general public health and safety edocuments/ucm htm FCC Wireless and RF Exposure Spectrum management Standards TCB route for approvals short turnaround 35

36 EU Regulatory 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 36

37 Typical Wireless Test Requirements Output Power Effective Radiated Power Frequency Stability Occupied Bandwidth Emissions Mask Power Spectral Density Spurious Emissions Immunity 37

38 Effective Radiated Power MedRadio MHz Maximum EIRP: 25uW = 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 (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. 38

39 Torso Simulator Cylindrical Plexiglas container with a size of 30 cm by 76 cm with a sidewall thickness of 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. 39

40 Radiated Emissions Test Setup EUT Vertical EUT Horizontal 40

41 Radiated Emissions Test Setup 41

42 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 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 C 42

43 Standards

44 Standards Inductive (communications) US EU FCC Part / 207 (tested in air) ERC/REC ETSI EN / -1 (tested in saline) ETSI EN / -1 44

45 Standards Inductive (charging portion only) US FCC Part 18 RF Exposure (KDB ) EU CISPR 11 IEC

46 Standards ISM/SRD US EU / / GHz Band MHz ERC/REC EN ETSI /-1 / / EN ETS / -1 46

47 Standards MedRadio/MICS US EU Part 95I / / 107 ERC/REC EN ETSI / -1 EN ETS / -1 Other Torso simulator 47

48 MBAN US EU Part 95I Standards ERC/REC Unknown we are to assume Part of MICS but could also be Wi-Fi stds or some combo EN ETSI / -1 EN ETS / -1 48

49 Wi-Fi/BT US EU Standards Part / ERC/REC EN ETSI EN ETS / -1 49

50 Medical Device Standards FDA IEC EMC of medical electrical equipment & systems IEC X specific types of equipment FDA Guidance Higher immunity levels might be required & have been requested 50

51 Medical Device Standards Other AAMI PC69 EMC for Active Implantable Medical Devices EN (Active Implantable Medical Devices) ISO (implantable cardiac pacemakers) EN & ETSI reqs ISO Standards (wheelchairs, pulse oximeters, neurostimulators) 51

52 Beyond EMC

53 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 C guidelines. More info: 53

54 Exposure Categories Fixed Mobile Portable 54

55 Exposure Limits FCC RF exposure limits are based on ANSI/IEEE C 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 55

56 Specific Absorption Rate (SAR) 56

57 SAR Test System 57

58 SAR Test System Radio Held Underneath Body Phantom 58

59 SAR Test System Radio Held Next to Head Phantom 59

60 RF Exposure Requirement for MedRadio Implants 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 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

61 Special Requirements Listen Before Talk (LBT) Required for MedRadio operation in the MHz band. EN 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 of EN shall be met. 61

62 Compliance Considerations

63 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

64 Write a Test Plan IEC , 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 64

65 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 65

66 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

67 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 67

68 Thank You! 68