Ideally, any technology is going to drastically affect people and the ability of people to accomplish whatever tasks they need. Yet, when new technology is entering the medical domain, the stakes are always a bit higher: one has to be cognizant that any faults, errors, or malfunctions are going to immediately affect someone’s health. Granted, not every medical device is going to be life-or-death, but they should still be considered carefully.
Designing for IoT is always a challenge, but medical IoT applications have an additional level of complexity that requires supplemental attention. Not only does your component selection process need to be more rigorous, but the design also needs to account for the device being subjected to heavy-wear and varied environmental conditions. Furthermore, safety and reliability have to be of the utmost priorities. Where do you begin?
Types of Devices and Wearables
You can typically consider healthcare IoT devices from one-of-two perspectives: engineering, or medical. From an engineering perspective, medical IoT devices are largely split into two categories: Implanted sensors and monitors, or wearables.
- Implanted Sensors and Monitors: These types of devices, from an engineering perspective, will have to be made with particular attention paid to the interaction of materials, components, and signals are affected by bodily movements. Furthermore, if designing implanted sensors or monitors, you will want to be sure to plan around power supplies knowing that, most likely, if a battery dies then there will have to be some form of invasive procedure done to deliver more power to the device.
- Wearables: While these devices are going to be similar in nature to implanted sensors and monitors, they’ll have different environmental needs - moisture resistance and greater flexibility - than implants. And while having consistent power is always preferable, wearables will be able to more adaptable to power demands than implanted devices.
From the medical perspective these devices get categorized based more on their affect: Devices critical for life management, non-critical devices for health tracking and life management, and health or fitness trackers.
- Vitals Tracking and Life Management: These electronics are going to be used for tracking things like pacemakers and ventilators. They are responsible for transmitting data collected on vital-for-life organs and systems. Attention paid to these devices should be wary of their role in critical bodily functions.
- Non-Vital Life Management: A classification of non-vital life management is not intended to dictate that these types of devices are any less important, but to diagnose that, essentially, the window-of-time in which a response is necessary if these devices fail tends to be significantly higher. These types of devices might be things like blood pressure or glucose monitors.
- Health or Fitness Trackers: Exactly as they sound, health or fitness trackers will keep track of data regarding step count, diet, caloric consumption for use in maintaining personal fitness and health.
No matter how you prefer to classify the devices, medical IoT electronics can drastically affect the relationship of data management for patients and personal care.
Layout and Systems Requirements
Medical IoT requires hardware that is very robust and capable of surviving the harsh and varied environments that patients put their equipment through. It might be a shower, a sporting event, or just day-to-day sitting around. While being robust, the hardware also needs to be sensitive enough to provide reliable data by collecting high-quality signals and filtering out any environmental noise.
Furthermore, the collected signals also need signal processing, which requires the microprocessor to have adequate speed and capability to manage whatever data handling is required for reliable performance. That might just involve interpreting analog inputs or something more complicated like removing motion artifacts from the input. Then, that processor needs to have low enough power requirements to function with a battery appropriate for a wearable application.
The design of your device is heavily determined by the form factor of the final product. Will you have a monitor on a portable stand? Will a patient wear it on-body? Does it stand alone in a patient’s environment?
The form factor of a medical or fitness IoT product will affect how patients and doctors use it.
On-body applications are frequently available as a wristband or watch. Because patients are familiar with wearing something on their wrist, it’s much easier to ensure the monitor is consistently worn. For a more aesthetic option, jewelry is another common option, with devices integrated into necklaces or brooches. Clothing is yet another popular option, with antennas or sensors integrated into the fabric. However, using clothes generally requires a connected piece of processing hardware, which reduces the appeal of using clothing. However, it is likely that improved electronic textiles will decrease the requirement for integrated electronics.
Some products don’t need to monitor a patient constantly and can take the form of a portable device or household object. Most household examples are focused on fitness, rather than medical applications, but similar principles can be applied. Some common examples are scales that link to a tracker app and give you long-term feedback about your progress in managing your weight and BMI. Another approach is attaching a sensor to a mattress to receive detailed information about sleep quality.
PCB design considerations for managing signal integrity are vital for IoT devices. You’ll want to trust that any connected device is capable of transmitting the correct signal within expected timeframes. IoT devices working through connectivity will rely on board design principles such as trace routing and trace width management, EMI and noise reduction, and keeping in mind necessary output signal strengths.
Power and power consumption are also facets of a circuit board which will contend with your design’s signal integrity. IoT devices have notorious track records with tough power consumption demands. Board layout software which utilizes strong routing tools and incorporates design rule checking directly into its interface would be of immense help in designing boards that are secure in their signal integrity management.
Design Challenges and Considerations: Systems, Signals Integrity and Data Handling
No matter what form your product takes, medical and fitness data is very personal and needs to be adequately protected for ethical and legal reasons. Of course, you want your users to have privacy and control over their own data; however, depending on the country you’re in, medical data is protected by various laws, like HIPAA in the U.S. This means that the security of data on the device, during transmission, and anywhere information is aggregated all need to be considered from both software and hardware mentalities.
Data needs to be secured at every level during transmission and processing.
You also want to plan for the interoperability of your product. Data compatibility may not fall under your purview as a hardware designer, but if it’s left unaddressed, then all your design work is wasted on a product that can’t perform as expected. You’re not off the hook for hardware, either. To be fully reliable and usable, tour system may need to interface with multiple wireless spectra or interact with other medical devices without any complications.
Although medical IoT can seem overwhelming, it is an excellent opportunity to serve patients and save lives. With such high stakes, it helps to use reliable tools that can match up to the task, like Altium Designer for PCB design.
To learn more about overcoming PCB design challenges to design reliable and robust medical IoT applications, talk to an expert at Altium.
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