Date: 04/10/2022
Design considerations for medical electronics and health monitoring product design
You need to have zero error, highly safe and reliable medical electronics systems. In that sense it is tough to design electronics for health monitoring and diagnosis. If not a graduate in medical sciences, you need to have some minimum knowledge on medical sciences. Not only design, manufacturing and selecting materials, components and software; they all need to fulfil a set of requirements. There are global as well as local controls and regulations in designing and manufacturing and use of medical devices. Either it is electronics or mechanical or whatever tech, it need to be in line with regulations.
If you look at the product portfolio under medical electronics: You can broadly classify them as patient monitoring and diagnostics, imaging/scanners such as MRI CT and ultrasound, lab test equipment for testing body fluids such as blood and urine, personal home healthcare/monitoring, and fitness equipment. However these days your smart phone and wearables are also turning into personal health monitoring devices which need to be further evolved to match the level of regulation compliance of exclusive medical equipments.
So first and foremost, an electronics design engineer need to be himself/ herself updated about regulations governing medical devices, and specifically medical electronics. If you are not updated with this knowledge and design a product, you end up totally redesigning the product.
Each country has its own medical regulations. International electrotechnical commission (IEC) is the standards body which defines specifications to meet. Most of the regions adhere to IEC specifications and standards. Two specification documents IEC 606601-1 and IEC 60601-1-2 are very basic and need to be fully informed.
To learn more about standards governing medical devices visit: IEC website:
https://www.iec.ch/government-regulators/medical-devices
and also refer the document at:
https://bioe.uw.edu/wp-content/uploads/2013/07/StandardsHandout_2013.pdf
This area is such a strictly regulated due to safety of the patient and operator involved. And also the reliability of the equipment.
Standards and regulations aside, today's electronics packed with lot of software and networking systems in such a way that the information is accessed remotely by doctors, patients and insurance agencies and any such related people. Ensuring privacy of the patient data and giving access only to the needy people is also a requirement. So in that sense of cybersecurity angle, information stored in the product need to be secured. Electronic medical data records need to be securely stored in computer systems outside the medical electronics devices. So the software component part of the design should take care of these requirements.
Let's look at the medical-electronics specific protection related technology requirements while designing medical electronics systems:
1. Electromagnetic interference (EMI), electromagnetic compatibility (EMC), and electrostatic discharge (ESD) are important things to be considered.
2. Though medical electronics doesn't work in harsh weather conditions, it should withstand harsh and erroneous electrical power input so that device does not fail in abnormal fluctuations and instabilities in electric power, while handling extreme power input, it should also protect the patient.
3. AC and DC power supplies inside medical electronics should withstand transient voltages and currents. These transients can resonate on the power bus. Medical systems should be protected against both voltage and current transients without impacting the performance of other parts of the system. They should also be designed to prevent any ringing oscillations.
4. To prevent high inrush current, medical electronic systems should have soft start feature to prevent inrush current stress and erroneous performance.
5. Medical electronic systems should be able to warn any imminent power and device failure to the user of the device. And also if for some reason medical device itself fails, or its subsystems fails, that failure need to be communicated to the user. So the designer should be able to anticipate various failure modes and provide remedies.
6. When selecting any component for medical electronics it should be as reliable as medical device you are making out of it. On the supply chain side, the part need to be supplied for long time without vendor obsoleting it.
7. Designer need to be aware of worst-case scenarios, real-world problems and the diverse environment.
8. Mechanical controls switches, knobs, touchscreens, and any such human interface devices need to be robust enough to withstand physical strain in extreme operating conditions.
Author: Srinivasa Reddy N
