cellular data connectivity The value proposition is easy to see and the advantages can be well worth the investment.
Connected medical devices are shaking up the industry. Look at just about any home healthcare device in the last few years: chances are, you’ll find some sort of wireless chipset inside to radio information to the internet for telemedicine purposes.

Having always-on cellular data included in your product can be a significant competitive advantage. For example, the newest generation of ResMed CPAP machines include cellular modems which automatically upload telemetry to ResMed’s servers. This allows patients and physicians to review data and more effectively manage sleep apnea.

The most common methods of connecting medical devices to “the cloud” are either through an onboard WiFi chipset, or via Bluetooth to a smartphone app. Both methods are relatively cheap, but they have their drawbacks:

  • WiFi is essentially free but requires the patient to connect the device to their home network. This can be a difficult technical barrier for many patients who aren’t tech savvy. Even if the patient knows their WiFi SSID and password, they still need to enter it into the device. If the device has a touchscreen, this can be done relatively straightforward. Otherwise, a smartphone app is typically required to set the network up the first time. Additionally, WiFi only works in the vicinity of the patient’s residence. This is okay for a device that stays in one place, but not very useful for 24/7 remote monitoring.
  • Tethering a device to a smartphone over Bluetooth solves the mobility problem, but doesn’t do much to alleviate the technical barrier. Bluetooth pairing can be a finicky, non-intuitive process at the best of times. As you are using a smartphone as a bridge, you will need to maintain an app that is compatible with any phone a patient might own. This is a quick path to a software maintenance nightmare.

These issues are exacerbated when you consider that the market for home healthcare devices skews towards the older generation. According to Pew Research, only 50% of the 65+ age group has a home broadband connection as of 2018 (source), and only about 46% of the same age group owns a smartphone (source). Potentially cutting off half of your target market out of the gate is far from ideal.

Fortunately, there is a third way: you can embed a cellular modem and SIM card directly into your medical device. This completely absolves the patient of having to deal with configuring their wireless network or pairing to a phone. All they need to do is go about their day using the device. Provided they are within range of a cell tower, everything will “just work” and their data will be uploaded to your server.

This approach works equally well for stationary devices at home and on-the-go. Despite historical concerns about “dead zones,” cell coverage is now ubiquitous. As per the FCC’s 2017 wireless market competition report, 99.8% of the US population lives in an area with LTE coverage (source). This is a much better percentage than the number of people who have in-home broadband.

Historically, gearing up for cellular connections on medical devices was expensive. The cellular modem itself is not terribly expensive (you can get an international cellular module for less than $30 in quantities of a few hundred units), but previously the data plan required for the device was cost prohibitive.

Getting an M2M (machine-to-machine) data plan in the past involved either comprehensive negotiations with cellular carriers, or accepting commercial rates and forking over tens of dollars per month. Since most medical devices are relatively low-volume, it can be difficult to secure the preferential M2M rates needed to make the business case work. This negotiation is required in every country of operation.

Today, things are much better. There are now several M2M SIM brokers who have done the difficult negotiation for you. Hologram, for example, offers a single global SIM card that works in over 170 countries. Pricing depends on the number of SIMs deployed, but at a volume of a few hundred units, $1.00 per month plus $0.38 per megabyte is typical. Brokers like Hologram make this capability available to medical device startups as well as the major players.

While the per-megabyte price sounds high, it is very reasonable when you consider that most medical telemetry is quite compact and compresses easily. Some careful protocol design is required to ensure low overhead communication, but this is a very achievable objective.

When deciding on a connectivity strategy for your connected device, consider going cellular. The value proposition is easy to see and the advantages can be well worth the investment.

Photo credit: ResMed

Peter Kazakoff wrote this blog as a StarFish Medical Electrical Engineer. A graduate from the University of Victoria, Peter received the Chris Denny Memorial Award for Innovation in 2017. He worked on a variety of medical device projects at StarFish, and recently relocated to Quebec to follow his dream and join the Canadian Space Agency Engineering training program. We wish Peter great success!


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