It’s official, I am now a ‘thing’ on the Internet of Things!
I suppose I should explain. As many of you who have read my articles and posts the last few years already know, medical devices in the Internet of Things is a topic that is near and dear to my heart. Literally. For more than 10 years, I have had a pacemaker (see my piece The Internet of Everything – It’s All about the Ecosystem). But until last week, I was not a ‘thing’ on the Internet.
Given the age of my pacemaker, I actually have to go in to the doctor’s office for them to read information off of it. Last week, my cardiologist placed an insertable cardiac monitor (ICM) under my skin to monitor my heart rhythms on a regular basis remotely. Knowing my interest in the technology aspects, my doctor arranged for me to have a demo version of the device (right), and its predecessor (left) from just two years ago.
Previous versions of cardiac monitors required day surgery to place the device in a patient. This new device was inserted under my skin in fewer than 30 seconds – living up to its name as an insertable cardiac monitor. You cannot even tell it is there, although I still have the scar from the pacemaker 10 years later. I have to admit; my inner geek could not help but be impressed at the technology that has made me a full participant in the Internet of Things. Needless to say, I had to dive deeper.
How Does it all Work?
Inside that tiny little device is:
- Sensors and cardiac-monitoring electronics.
- Storage for recording of the results.
- Programmable control electronics to determine what gets recorded, saved, and transmitted.
- Radio Frequency transmitter to send the information to a base station, called the patient monitorg (more on that below).
- And a battery to power it all.
Along with the device, I was given a base station for in my home. When my doctor programmed the device, it was paired with this base station. My device will only send information to that base station, and that base station will only receive information from my device, communicating wirelessly. The base station also has cellular technology built in and is connected to a private network via that cellular link and uploads the information it receives from my device. Servers on that network store, analyze, and generate reports on the data and then are emailed directly to my doctor. Additionally, the raw data is available to him through an application.
Questions. So Many Questions.
Naturally, the questions started building:
- What about data privacy and security?
- What about the sheer volume of data?
- How long does the battery in the device last?
- How long does the device last?
- What about upgrades — to the device and or to the base station?
All of these questions can be applied to just about any device in the world of the Internet of Things. Now that one of them was a part of me, the concepts went from the theoretical to the real world very quickly.
Data Privacy and Security
Data privacy and security, and how they are addressed, is a huge concern in the IoT space. For my device, there are multiple steps taken to address this.
- Neither the device nor the base station have any information about me as an individual, the classic PII (Personal Identifying Information). Both the device and the base station have unique id’s, which are transmitted with the data.
- These id’s, as well as the pairing, are registered in a database on the private network that is receiving the data. Both IDs must match for the data to be accepted on the server.
- The server environment is subject to the standard HIPAA privacy standards, and connects the transmitted data with who I am.
- The RF transmitter in the device is very low power (which also is part of the battery life discussion), with limited range (approx. 6 ft), and will only communicate with a base station it has been paired with.
Another challenge in the IoT space is data volume. Sensors can collect huge amounts of data. In my case, collecting heart rate data 24 hours a day, seven days a week is a lot of information. This could quickly consume physical space in a device, as well as bandwidth in transmitting this data wirelessly and through a cellular network. This challenge was addressed by understanding the simple question: What data is important?
For my device, the only time the heart rate information is interesting is if something out of the ordinary has happened, an event has occurred. Understanding this provided some flexibility in the design considerations:
- The device itself is effectively a loop recorder. The primary storage can hold 20 minutes of heart rate data. If nothing out of the ordinary happens, it simply loops and overwrites the uninteresting data.
- When an event occurs, the device records the date, time and event type. Additionally, it takes a snippet of the loop, a few minutes on either side of the event, and stores that for transmission to the base station.
- If other events occur, the process is repeated.
- At scheduled intervals, the device will transmit a list of any events that occurred, with time and date, plus data for the first event only to the base station.
- It was explained that limiting the data to the first event only is to help with the battery life.
- The doctor can request all the data be sent. That is accomplished by either
- Contacting me and having me push a button on the base station (manual intervention).
- Go into the doctor’s office and use a similar device to request the information from the device.
- The base station transmits the data to the servers via the cellular network.
Battery and Device Life
Battery life is a constant pain point in any mobile or IoT scenario. For some devices, recharging is an option. Needless to say, this device is in my chest and there is no way I am connecting myself to a recharging cable! Add to that, for this type of device — a cardiac monitor — it must be able to last for an extended period of time. It is used to try and catch what may be infrequent cardiac events. While they are simple to insert, neither the doctor nor I want to keep replacing it on a regular basis just because the battery has run out. It’s balancing the tradeoffs. The expected battery life for this device is three years. They are able to get it to last this long by some of the techniques already mentioned:
- The RF transmitter is very low power with limited range.
- Data is only transmitted at specific times (usually when one is sleeping).
- Minimum amount of data is transmitted by default, with options for manually triggered full transfers (which consumes more power).
Given the size of the device, this challenge is magnified, but no matter the size, battery life for any ‘thing’ in the Internet of things is a constant challenge. Just think about your mobile phones. As we keep adding more features and apps, we watch the battery drain away quickly. Optimizing app usage on any device is a constant balancing act between providing useful functionality vs. consuming battery power.
Both the device inside me as well as the base station are ultimately programmable devices. This means there is the potential of software updates. The base station can be updated remotely as it is constantly connected via the cellular network (similar to automatic updates for your mobile phones). The device inside me is more of a challenge. Given that there is no guarantee it will stay within wireless range of the base station; remote updating under those circumstances is not a realistic option. If there is a need to upgrade the software, that would involve a visit to the doctor’s office. The upgrade would still be done wirelessly, but in a controlled situation.
Welcome to the Internet of Everything
All of the musings and questions I raised are serious considerations and challenges in the ever growing world of the Internet of Everything, no matter that those ‘things’ are. As with everything in the world of technology, there is no one-size-fits-all, single answer. How those challenges are handled for my heart monitor were made with that understanding, and based on the tradeoffs, that made the most sense given its requirements. As technologists, we must always make sure we ask the questions and are able to explain the tradeoffs to the business to help achieve the balance that is right for the given business scenarios. For me, one thing is for sure. Now that I am a ‘thing’ in that environment, I will be coming at those questions with a whole new perspective!