Comparing Wi-Fi Options for Medical Devices

October 17, 2014, 3:31 pm

As the Connected Hospital continues to become a reality, more and more medical device manufacturers are looking to add wireless capabilities to their devices. Connecting wireless medical devices to a hospital network not only improves workflow, but saves in financial costs as well. Once medical devices are on the network, clinicians can remotely monitor patients from any pint in the hospital and technicians can manage the devices from a central point of control. For portable and mobile devices, the optimal technology for network connectivity is Wi-Fi. To add Wi-Fi Connectivity to a device, manufacturers add a Wi-Fi module to the device. There are two typical approaches to integrating a Wi-Fi module into a device: using a simple module and using an intelligent module.

Which Module is Optimal for a Medical Device?

To determine the best module type for a medical device, device manufacturers should consider the following factors:

  • Medical device computing resources
  • Costs
  • How Wi-Fi software maintenance and upgrades will be handled (support)
  • Device design priorities

Medical Device Resources

A Wi-Fi module is driven by software. Wi-Fi software components include a device driver, a security application called a supplicant that handles network authentication and encryption key derivation, and utilities for configuring and managing the module. In addition, applications that leverage Wi-Fi connectivity require software resources such as a TCP/IP stack.

A general-purpose computing device has the resources required to support Wi-Fi software and related resources such as TCP/IP run on the device’s operating system, which operates on a robust processor with plenty of memory. However, a medical device may lack the resources required for Wi-Fi since they are typically designed for a single purpose, not to run general-purpose applications. An intelligent Wi-Fi module may be the best choice for a medical device with limited computing resources because it runs on its own operating system, and the Wi-Fi software operates on that operating system instead of the medical device’s. Rather than using a medical device’s computing resources for Wi-Fi, an intelligent module brings a complete Wi-Fi subsystem to the medical device.

Costs

The price of an intelligent Wi-Fi module is typically higher than that of a standard module, but the cost of integrating a standard module into a medical device is much higher than the cost of integrating an intelligent module. An intelligent module is like a small computer dedicated to Wi-Fi connectivity. Integrating this Wi-Fi computer into a medical device is a straightforward process, where the primary task is enabling a basic connection through a board-to-board connector. No special software has to be installed or tested on the medical device.

With a standard module, the integration process is more complex. Typically, the module must be soldered directly to the host device’s motherboard. Some standard modules support a board-to-board connector, but those modules are more expensive. In addition to potentially difficult hardware integration, a standard module requires integration of Wi-Fi software on the host device. To ensure that the module provides secure and reliable connectivity, rigorous testing of this software on the device is a must.

A company with strong internal Wi-Fi expertise can achieve successful integration of a standard module, but the effort may take several months. Integrating an intelligent Wi-Fi module is the safer approach and also results in a faster time to market. For a high-volume device, however, the higher purchase price of the intelligent module may make it the more expensive option.

Wi-Fi Module Support

How the module is supported is an important consideration in module selection. Supporting a Wi-Fi module in devices deployed at customer sites can be difficult for a medical device maker because W-Fi support requires specialized expertise. Often device makers rely on contractors to handle Wi-Fi integration projects (including porting of Wi-Fi software to a medical device’s operating system). When a support issue arises at a customer site, the contractors who understand the module and its software best may be unavailable to assist with troubleshooting and resolving the issue.

With an intelligent module, the Wi-Fi software runs on the module, not on the medical device. The module supplier typically provides support for the module hardware and software, even after the module is integrated in a medical device and deployed at a customer site. Because a medical device may be used for 10 years or longer, ongoing support of Wi-Fi modules in deployed devices can represent a significant area of “hidden” costs. Thus, the costs and risks of support must be considered before selecting a Wi-Fi module.

Design Priorities

A few additional design elements should be considered when deciding which Wi-Fi module option works best for a medical device:

  • Because a standard module is smaller in size, a smaller footprint can be realized by connecting the module directly to the devices motherboard
  • A standard module consumes less power than an intelligent module.
  • With an intelligent module, FCC grants for the module can be leveraged for device-level certifications. In other words, once the intelligent module has been fully tested and certified for FCC compliance, compliance extends to the device in which it is integrated because the module and its software remain unchanged after integration. Even when a standard module has its own certifications, additional host device testing in required after the module is integrated.

As you can see, there are quite a few considerations to make when adding Wi-Fi connectivity to medical devices. Once the best module type for a medical device has been determined, manufacturers must then choose a specific module. Medical device makers should make sure the wireless solution they choose to embed into their medical devices is equipped with the latest certifications. Given the sensitivity of data being transmitted, top of the line security feature sets like WPA2-Enterprise security and FIPS 140-2 should be available.

Check out the Connected Hospital to learn more about Wi-Fi in healthcare.

Portions of this blog post were originally written by Laird and published by Product Design & Development. Click here to read the original article.