Body-worn brain stimulator (MOPP isolation requirements)

william guo

Starting to get Involved
#1
Hi All,
We have a medical device which is body worn for >30d. It is essentially a electrical brain stimulator. It have a plastic enclosure and two patient leads which will be implanted into patient during clinical use. The device will generate a (0-11.5mA/1.1Hz ) current to sitmulate patients brain. Intern circuit comprise 3.3V li-on battery, control IC and drivering circuit, and no SIP/SOP. Applied parts classified as TYPE BF.

For the electrical shock, we considered the whole device (patient lead/electrode and enclosure) as applied parts. my question is:
1) is 2MOPP necessary between internal circuit and plastic enclosure? based on working voltage 3.3Vdc​
2) because the device is body worn, I don't think we need 1MOPP based on 240V mains between internal circuit and enclosure, then the patient leakage current measurement is not necessary also.​
3) how about the Patient auxiliary current? because cl. 8.4.2 a) requires that the "current" shall not exceed limits in table 3 and table 4. And in cl. 8.5.1.1 requires that" ME shall have 2 MOPs to prevent applied parts and accessible parts from exceeding the limits in 8.4.​
This means that we shall have 2 mopps to limit the Patient auxiliary current. If we use resistors, then is the cr/cl and electric strength test applicable to this resistor, as specified in ANNEX of CL.4.8?

Thanks
 
Elsmar Forum Sponsor
#2
Hi William,

I think for the implanted parts of the system, you could instead refer to ISO 14708 and in particular it sounds like 14708-3 Implantable neurostimulators could be applicable to your device. I think you will find that these standards will provide more relevant testing scenarios.

Matt
 

william guo

Starting to get Involved
#3
thanks matt.
Here I share some points got from IEC SC62.
1. For body-worn device, they didn't accept the 12cm patient lead/cable rule which proposed by IEC WG14 in IEC/TR 60601-4-3. We still need 1MOPP between patient circuit and Enclosure based on mains voltage.​
2. we still need 2MOPP based on working voltage between internal circuit and enclosure to show the evidence that unwanted leakage current path between electrode and enclosure does not exists.​
3. For PAC, they said the current is intended for physiological effect, it's not necessary to consider it. However, this is not a sound clarification from my point.​
The standard defines PAC as “ Current flowing in patient in normal use between any patient connection and other patient connections and not intended to produce a physiological effect”.
From my point, this implies that we shall consider the current which has no intended physiological effect during normal use, and if this current exists, we shall limit it.

For our device, there are two working modes should be considered during normal use.
1) Stand-by mode – the power is on but the stimulation current is not activated​
In this mode, we shall keep the electrodes at the same potential (neutral, from the technical feasible view), otherwise, a current will flow between electrodes. Is this current considered as PAC? If yes, I think we shall apply relevant requirements of cl.8 for the means to keep electrodes neutral.​
2) Stimulation mode – the device will output the intended therapying current.​
In this mode, there will be some unintended DC (<0.1Hz) component of the stimulation current.​

Is this “DC component current” considered as PAC? If yes, I think we shall apply relevant requirements of cl.8 also for the means to limit the "DC component current".

William
 
#4
Hi William,

Maybe I misunderstood, and your product is applied to the skin of the patient? I will assume that your device is an external stimulator similar to a TDCS system.

Then, for 1) Yes, I would understand any current flowing when stimulation is not active as PAC.
2) Yes, any current flowing that is not part of your intended stimulation pattern would also qualify as PAC.

I think the intention of the standard is to say that you have some stimulation pattern you want to apply, and you have some scientific or clinical evidence for that stimulation pattern. The standard then asks you to make sure that all other energy applied to the patient is below a low threshold. This helps to reduce the risk of side effects. So you are doing well to consider any unintended currents (AC or DC) as PAC, in my opinion.

Hope that is helpful.
Matt
 
Thread starter Similar threads Forum Replies Date
G Is impact test according to IEC 60601-1 applicable for HAND-HELD equipment if also classified as BODY-WORN? IEC 60601 - Medical Electrical Equipment Safety Standards Series 1
L Is a RJ45 LAN Connector worn on Body Medically Safe? IEC 60601 - Medical Electrical Equipment Safety Standards Series 2
R Does long-term body worn medical monitoring device need to meet IEC 60601-1-11? IEC 60601 - Medical Electrical Equipment Safety Standards Series 4
M IEC60601-1 Battery Powered Body Worn Device Leakage Currents IEC 60601 - Medical Electrical Equipment Safety Standards Series 7
C Medical device worn on body with USB, isolation, 60601-1 IEC 60601 - Medical Electrical Equipment Safety Standards Series 4
Ed Panek Notified Body Substantial Change MDD EU Medical Device Regulations 1
S Certification Body Changeover - Transfer of Certificate Registrars and Notified Bodies 9
J Should a Class 1 medical device with an option to measure body weight be considered Class 1m? EU Medical Device Regulations 0
M Spain Notified Body Medical Device and FDA Regulations and Standards News 0
M Notified Body Spain Other ISO and International Standards and European Regulations 0
M Spanish Notified Body - Spanish language CE Marking (Conformité Européene) / CB Scheme 2
K MDR Class 1 Self Certification - Competent Authority or Notified Body? EU Medical Device Regulations 6
B IATF 16949 Cert Expire- New certification body IATF 16949 - Automotive Quality Systems Standard 5
J Intervertebral body fusion cage, MDR Class II or Class III? EU Medical Device Regulations 4
P Notified Body Approval of Change EU Medical Device Regulations 2
M What happens to certifications if the issuing certification body loses accreditation? Supplier Quality Assurance and other Supplier Issues 2
K Adding the Notified Body Number CE Marking (Conformité Européene) / CB Scheme 2
Marc Mule Car aka Body Mule Definitions, Acronyms, Abbreviations and Interpretations Listed Alphabetically 6
A NB (Notified Body) Audit of Standards ISO 13485:2016 - Medical Device Quality Management Systems 3
J Conflict of Interest Registrar/Notified Body/Testing House Quality Manager and Management Related Issues 4
JoCam Certified Body Audit of MDR requirements EU Medical Device Regulations 4
R Change Notification - Registrar vs Notified body ISO 13485:2016 - Medical Device Quality Management Systems 1
Watchcat "Disappeared" Linkedin Notified Body Rant EU Medical Device Regulations 2
M Notified Body audits -Class Ia medical device product EU Medical Device Regulations 4
R Notified Body for MDD 1Q20 - Florida Company Registrars and Notified Bodies 4
M Informational EU – New notified body designated under the MDR – NB 2797 BSI Group The Netherlands B.V. Netherlands Medical Device and FDA Regulations and Standards News 0
M Informational EU – New notified body designated under the MDR – NB 1912 – DARE!! Services B.V. – Netherlands Medical Device and FDA Regulations and Standards News 0
N Customer asking if their notified body can audit us ISO 13485:2016 - Medical Device Quality Management Systems 5
N MDR review process by notified body - How many steps exist in the review process EU Medical Device Regulations 0
Ed Panek CAPA against Notified Body? EU Medical Device Regulations 5
M Informational EU – First IVDR designated Notified Body – DEKRA Certification GmbH Medical Device and FDA Regulations and Standards News 0
N Regular meetings with Notified Body EU Medical Device Regulations 13
M Informational EU – New designated Notified Body under the MDR – TÜV Rheinland LGA Products GmbH Medical Device and FDA Regulations and Standards News 0
M Informational New designated Notified Body for Regulation (EU) 2017/745 (MDR) included in Nando – IMQ ISTITUTO ITALIANO DEL MARCHIO DI QUALITÀ S.P.A. Medical Device and FDA Regulations and Standards News 3
M Informational EU – Next Notified Body designated to the MDR 2017/475 is IMQ S.p.A from Italy Medical Device and FDA Regulations and Standards News 0
M Informational EU – DEKRA Certification GmbH is the third Notified Body designated under the MDR Medical Device and FDA Regulations and Standards News 0
JoshuaFroud The withdrawal of Lloyd’s Register MDD & IVDD Notified Body Status CE Marking (Conformité Européene) / CB Scheme 1
M Measurement Unit Rounding Nonconformity - Notified Body Audit Registrars and Notified Bodies 6
M Informational From RAPS – Another Notified Body Bows Out Ahead of EU MDR: ‘Investment Too High’ Medical Device and FDA Regulations and Standards News 2
M Authorized Rep (AR), competent authority, NCA and notified body - Differences EU Medical Device Regulations 9
R How long to wait for Notified Body Response - Potentially significant change to a medical device CE Marking (Conformité Européene) / CB Scheme 6
M Informational New Notified Body designated under the MDR – TÜV SÜD Product Service GmbH Zertifizierstellen Medical Device and FDA Regulations and Standards News 1
shimonv Non-significant notice of change to notified body EU Medical Device Regulations 4
J0anne Implantable Devices - The effects of surgical scaffold implanted into the human body Other Medical Device and Orthopedic Related Topics 8
C TL-9000 Certifying Body Issue - Auditor failed to find an issue for 10 years TL 9000 Telecommunications Standard and QuEST 16
S Difficulty Finding A Notified Body for CE Marking - No Capacity Registrars and Notified Bodies 5
M We still have not received our certificate due to a 'backlog' with our auditing body Registrars and Notified Bodies 25
N Creepage - Does a surface mount isolator body negate a PCB slot? IEC 60601 - Medical Electrical Equipment Safety Standards Series 6
P Notified body located in an other country than manufacturing company ISO 13485:2016 - Medical Device Quality Management Systems 2
T Reasons to change certification body and typical costs Registrars and Notified Bodies 16

Similar threads

Top Bottom