Imagine you are recovering from an operation and are fitted with wireless body sensors that allow you to move in the hospital bed or around the room in comfort. Once past the critical recovery stage, you are given the option to leave early if you take the sensors with you. Relaxing at home, your healthcare providers monitor your vital statistics transmitted via a wireless hub connected to your home network.

Fig. 1 – As medical devices integrate more RF and connectivity features, new test and compliance strategies are required. (Credit all images: Averna)

Due to advancements in connectivity, such a scenario is likely to become the norm for post-operative care. But how do we get there? And how do medical device companies ensure we get there safely and securely?

First, let’s first explain what we mean by “connectivity,” because it can have multiple meanings in our industry, including:

  • Connections between devices and smart sensors, and
  • Electronic health record exchanges.

This article will explore these types of connectivity with a focus on how current and near-term changes will likely impact product designs, compliance approaches, and device testing.

Wireless Connectivity and New Regulatory Burdens

One of the biggest connectivity leaps underway in the industry is wireless communication. More and more products are being designed with radio-frequency (RF) chips and capabilities that will allow them to communicate with other devices and networks. Once RF is added to a medical device, however, the regulatory burden often doubles.

For example, medical devices used in the US are regulated by the FDA, which requires extensive quality and safety processes for both product design and manufacture. When RF technology is designed into the medical device, a whole new regulatory agency, the FCC, has its own sets of requirements for product testing, documentation, and compliance. For products used outside the US, there are similar foreign agency regulations, such as ETSI, EMA, and CE marking. (See Figure 1)

Background: The Rise of RF in Medical Devices

One early RF application came about as a way to communicate with an implanted device. In 1999, the FCC allocated spectrum for Medical Implant Communication Service (MICS) and then later expanded it for Medical Device Radiocommunications Service (MedRadio) in 2009.

This spectrum (401 to 457 MHz) is allocated for the use of diagnostic and therapeutic purposes in implanted devices (such as pacemakers and defibrillators) as well as devices that may be worn on the body. These frequencies were chosen to minimize the damage to tissue that radio frequencies might have caused when passing through the body.

Because of the need for rigorous RF testing required for such MICS- and MedRadio-enabled devices, many medtech companies partnered with RF test experts to create and implement the appropriate test and compliance strategies at both the R&D and manufacturing stages.

Consumer RF Test Expertise Making Inroads

When RF tests and measurements are needed for a medical device, many best practices can be leveraged from outside experience, such as the testing done in the cellphone and cable modem industries. Advanced test systems for such “RF rich” consumer electronics need to test multiple RF protocols, including WiFi (IEEE 802.11), Bluetooth, ZigBee, NFC, 2G, 3G, 4G, GPS, DOCSIS, etc. The same principles and best practices can be ported to the medical device space, as a subset of testing under the broad guidelines of the FDA’s 21 CFR Part 820 (practices for quality and safety). (See Figure 2)

Today, the medical device industry integrates many of these consumer RF standards with medical standards like Wireless Medical Telemetry Service (WMTS), MedRadio, and Medical Body Area Network (MBAN). This multitude of standards implies that many new medical devices will have several RF antennas and will need to be tested for multiple RF protocols and frequency bands.

While the complexity of RF connectivity can be daunting, the good news is that most of the protocols are mature and, therefore, the necessary test strategies and equipment are already in place at companies that test consumer devices, meaning they can be integrated and adapted for the specific purposes of medical devices and hospital environments.

Medical Design Briefs Magazine

This article first appeared in the April, 2015 issue of Medical Design Briefs Magazine.

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