Increasingly medical devices include Digital Health connectivity.  StarFish engineers Sal Sanci, Dean Addison, Mike Sanders and Nigel Syrotuck explore the pros and cons of popular communication technologies over a series of blogs on the subject.  This blog examines Digital Health communication technology options for medical devices.

Wi-Fi and Bluetooth are important for digital health devices because you typically want it to be portable and small.  If you want it to be portable, you want it to be wireless and have a small battery. There are always considerations for how you want to get data off of the device. Wi-Fi and Bluetooth are the standard options.  There are also versions of Bluetooth that are low power (i.e., Bluetooth Low Energy – BTLE).

The majority of the difference between Wi-Fi and Bluetooth is power and protocol.  It’s just a matter of the software driving the wireless radios in different ways. Range is another difference, but it is almost always related to power. If you want to go far, you need more juice. Often these protocols or technologies will be limited to a particular range.  If you want outside that range, you will need Wi-Fi or cellular modem or something similar and then the cell saving power goes up. Bluetooth wants to standardize mesh-networking support in 2016 and includes it in their 2016 technology roadmap enhancement plans.

Cons:  Wi-Fi takes more power than Bluetooth. Implant or ingestible devices will likely never use Bluetooth or Wi-Fi because you can’t put them through the human body (they both exist at about the absorption peak of human tissue). The FDA and FCC have some agreement on what acceptable power levels are and what needs to be done.

Many clients are using cellular.  If your device needs to connect from remote places – like cities that don’t have Wi-Fi everywhere, use cellular.  It is now largely a data network that happens to carry voice rather than a voice-calling primary network.

One of the reasons it is popular is because it’s not that controlled.  In a healthcare environment where most networks are highly controlled and need to be used for operational purposes, having less mission critical data somewhere off-network can be really valuable. In theory there would be no installation effort needed because it just works.  You don’t have to put in a Wi-Fi password or hook it up to Bluetooth or anything.

Healthcare system networks, particularly in tertiary care, are difficult to manage.   IT managers are inundated with experimental products that need their networks.  At the same time they have to maintain high reliability. They will be reticent to put anything physically on or integrated into their networks. Trying to add a new, innovative system to the network will be an uphill battle unless it is mandated or made a priority. Stepping outside the hospital network circumvents this entirely, especially if you can buffer the data and put it on a wireless network like a cell phone.  They are ubiquitous, you don’t have to put anything into place, and the cost is low.

Cons: In urban centers cellular data is great—very low power, very high bandwidth. Head out to the bush and in two hours your battery goes dead trying to communicate and data rate is negligible. Cellular is a line of sight technology. It can be costly from a power standpoint outside of an urban center.

Using a cellular network for critical data is not a good idea. You can get drop outs and coverage is not guaranteed (especially in the basement of hospitals). Applications that require real-time monitoring are not going to be the first ones implemented because there is an established management philosophy for dealing with them. There is an understanding of how and why you handle real-time data.

Satellite Networks are cool, but expensive. They are good for disaster or low-infrastructure situations. They are probably not much benefit for those in developed countries. An exception would be a product like the LifeGuard Vital Signs Monitoring System, developed by NASA Ames Astrobionics and Stanford National Biocomputation Center. Mobile first responders and military personnel strap it on to their body.  The device acts as the base station for communicating out information.  If the patient is on a stretcher, the stretcher can be instrumented.  EKG/ECG patches on the patient are attached to the instrument on the stretcher and radioed out.  An advantage is knowing how first responders are doing because they are also instrumented for pulse rate, blood pressure, position (standing up or laying down), etc.

Mesh: A mesh network is a network topology in which each node relays data for the network. All mesh nodes cooperate in the distribution of data in the network. For all of the devices that won’t get onto a hospital network, MESH networks are an option.  A lot of experimentation is going on right now with both Bluetooth and WiFi, as well as wired networks. Although far from ubiquitous, MESH network connections are possible.

Near Field Communications (NFC) or Radio-frequency Identification (RFID) are neat technologies, but devices have to be near each other to communicate.  It can be very useful if the device is nearby.  An example could an unpowered alert bracelet, which can give emergency responders critical medical information.

RFID is already used for inventory management in hospitals.  There is an RFID standard specifically for implantable tags. This is mostly used for pet identification.

NFC is used by doctors in combination with a security code for two factor authentication. For example, NFC can be used to fulfill a prescription from a kiosk by logging the pharmacists ID with the swipe of a tag and a password. The transaction is automatically logged. In a different application, putting NFC in a shoe can also provide measurements like temperature or weight pressure for very long term, low cost monitoring for any chronic disease like cardiovascular or Alzheimer’s.

Cons: NFC and RFID technologies are limited in their application. Low cost makes them desirable, but are only useful for transmitting a few bytes of data over distance of just a couple inches. This drastically narrows their applications.

Smart Phone Connectivity is another great option for cloud connectivity. Be it a physical dock or Bluetooth, getting data from your device to your phone, and then off to the races is an effective strategy for enabling digital health. Once the data is out of the device it can be stored elsewhere, quickly processed, displayed to the user, and then bounced on to the cloud essentially for “free”.

Con: Smart phones can be a high maintenance way for getting data off of your medical device, essentially due to a lack of control as to how the smartphone is operated, updated and validated. That being said, Mobile medical applications are certainly feasible and popular amongst a number of devices.

Once you are at the stage where you have data off the device, you will have to have a consumption platform to receive it.  Where is that data going? How are you going to speak to the world in general? This is where the rest of the arguments come in to play.