Mobile Medical Devices: A Trip to the Trenches of Design and Test

Mobile Medical DevicesA Trip to the Trenches of Design and Test

Medical Device Summit, Boston, MA. February 25, 2014

Daniel Sterling, President

What we do:o System Design, Development and Test

Software and Electronics Experts Any Phase

o Risk planning and hazard identificationo DHF Remediationo Project Rescueo Quality System Consulting

450+ Medical Projects, 125+ Clients

Who is Sterling?

ISO 13485FM 543438

Registered

IEC 62304 Compliant

Your Partner in Medical Device Development

There when you need us!

Design and Test RisksThe more things change…

• Requirements not well defined • Design team too large or too small • Design team does not have enough experience in

the technologies being used• Design Decisions Not Clearly Documented/Captured• Challenges around user preferences

– ‘Sexy GUI’ vs. battery life/recharging frequency.

Design and Test Risks… but, Now There’s More

• Obsolescence/Configuration Control

• Tradeoffs More Difficult

• Data Transport Specific Challenges


• Obsolescence/Configuration Control– Mobile product obsolescence – phones and wifi-only devices like

iTouch and Android devices come and go rapidly compared to the lifespan of medical device systems.

– HHDs (Hand Held Devices) Part Dependency - if you are using parts that are popular for phones and the phone is then discontinued, the availability of parts tend to dry up pretty quickly, or become rather expensive since the volume disappears. This can put a real glitch in a mfg schedule / device cost; plus the mfg often has to purchase enough inventory of the current part to hold the product in production until a redesign can occur.


• Obsolescence/Configuration Control

– Life cycle management of the selected product will be key not only during development but during production.

– The manufacturer (Apple, Motorola, Samsung) could make slight changes which have a –severe- impact on the final design.


• Difficult Tradeoffs

– Feature Richness vs. – Battery Life vs.– Communication Robustness vs. – Validation Requirements vs. – Security Considerations…

When a good portion of the design is out of your control, How to best integrate the mobile device into your medical system

Design and Test Risks… how do you Integrate?

WiFi

• Robustness across a variety of LAN configurations requires more system planning– Home use devices – To support the average, non-technical users, requiring

advanced configurations like port forwarding may be unworkable – Server technologies can be implemented to circumvent network address

translation issues and to enforce Security to prevent unauthorized access


WiFi

• Server to prevent unauthorized connections – – by authenticating all users of the iPhone app, and to facilitate

secure connection pairing. The peer-to-peer connections are authenticated using session keys generated by the server.

– to ensure maximum security all ports that are not used by the system should be closed.

– all communication encrypted.


Bluetooth/BLE

• For Short Range • They are not the same

– On the device side, implementing one and then switching is time consuming and costly, so plan ahead

– BLE has less compliance requirements from Apple

• Hardware Considerations– Modules (pre-certified) vs. Raw chips

• Raw implies FCC Certification will be needed– Modes supported (client and/or server)


Bluetooth/BLE

• BLE, Reduced Power Consumption – Sleeps Most of the Time• iOS has CoreBluetooth – Need to Understand Restrictions• Off The Shelf Stacks May be Unstable – Need to be able to modify


Cellular

• 2G/3G/4G choice:– Need to balance cost, coverage, and lifespan of technology– 2G – Frequencies compatible with all carriers in a given region (only 4 bands worldwide),

lowest cost, widespread coverage throughout the world. 2G service will be deactivated by 2018 in many regions. Extremely slow data rates.

– 3G – Higher cost, slightly more “fragmentation” on the frequencies used across carriers. Good coverage and good data rates for most applications. Cost of implementation is higher than 2G but expected to go down as time goes on. Will probably live beyond 2020.

– 4G – Highest cost, antenna design more difficult due to band fragmentation among carriers (e.g. Verizon, ATT, and T-Mobile all have different LTE bands that only partially overlap). Limited coverage outside of major metro areas.


Cellular

• Module vs Discrete IC implementation:– Modules are expensive and physically large and may have higher power consumption due to

on-board processor not required in a discrete implementation. – Modules can be cheaper when adding in development costs, because you can re-use part of

their FCC certification (but not all). How much depends on your implementation details. Expect to perform, at least, EMC testing to FCC Part 15.

– Modules may have higher levels of conducted harmonics than the best discrete implementations, making it more difficult to pass EMC testing (PTCRB or Verizon/Sprint approval).

– Discrete implementation requires significant RF expertise on staff, longer development time, and may require work with the cellular carrier directly for approval. FCC submission significantly more burdensome as there will be no existing submission to leverage.


Cellular

• EMC testing difficulties:– Due to the high power levels of cellular transmitters (up to 2W / +33 dBM), there are

very real concerns about both RF ingress to other circuits in the device, and harmonic emissions due to interactions with other components in the device.

– Must pass PTCRB certification in the US market if you are using a GSM carrier such as AT&T and T-Mobile. Verizon and Sprint have their own similar requirements. Carrier certifications have extremely strict limits for emissions, much more difficult than the FCC requirements.

– Expect to have to use a custom / tuned antenna design to meet carrier requirements. Off the shelf antenna designs will often lead to emissions failures or power levels below required limits.

– Plan to do pre-compliance testing early and often


RF Communications

• Used for Legacy I/O – We have created Bluetooth <–> RF “translator” interfaces

• Transfer Power (along with I/O)• Can Have Cost, Risk Advantages• However, Not Available On Smart-Devices

Compliance ChallengesOTS Mobile Devices

• Inability to verify if OTS mobile devices comply with IEC60601 and IEC 62133 (electrical and battery safety)

• May not pass:– Particle and Liquid Ingress (IPXX)– Drop Testing per 60601-1-11

• Use UL Approved Devices– Premium cost but may save valuable time late in project

• OTS OS, Software – Controlled, Validated

Thanks to the follow for their valuable contributions:Bruce Swope Lawrence BischoffChris Bradley Keith HandlerSteve Hartman Jamme TanJohn Campbell

Mobile Medical Devices,A Trip to the Trenches of

Design and Test

Contact for more information:Erik HilliardDirector of Business DevelopmentSterling Medical Devices201-227-7569 x155ehilliard@sterlingmedicaldevices.comwww.sterlingmedicaldevices.com

Mobile Medical Devices,A Trip to the Trenches of

Design and Test

mailto:[email protected]?subject=Assurance%20Case%20Presentation

http://www.sterlingmedicaldevices.com/


WiFi

• To create a peer-to-peer connections over the internet without requiring the user to configure port forwarding we used a primary connection method with a more reliable fallback method:– The first method is UDP hole punching - This method has been shown to

work on the majority of commonly used routers and, if successful, allows a direct peer-to-peer connection across NATs without requiring port-forwarding.

– The second method is to relay all packets through a central server. Each device (the iPhone application and the medical device) makes an outgoing connection to the server which relays all packets between the two.

Devices & Hardware

Mobile Medical Devices: A Trip to the Trenches of Design and Test