Wireless connectivity defines the user experience for much of the technology we rely on every day, whether we’re logging into work from a home office, sharing content from our favorite streaming platform or swiping our phones at the grocery checkout line. The healthcare industry is no different and each year spends billions on wireless medical devices that perform essential clinical functions such as patient monitoring, infusion and diagnosis.

The medical field is conservative by nature. Nevertheless, it has excelled at designing wireless solutions to meet a range of use cases, from neonatal vital signs monitoring to a growing geriatric population in need of wearable and implantable devices. The outcomes are remarkable in their ability to improve the quality of patient care. However, embedding Bluetooth® or Wi-Fi components to accurately track glucose levels or securely transmit real-time patient health data to a nursing station is a complex task that requires core wireless engineering expertise that device makers may not possess. 

This lack of know-how can create a blind spot in which med-tech companies may inadvertently neglect to adequately test their wireless devices as they graduate from a concept in the lab to the volume production line. The oversight can lead to device under-performance in which patients may experience poor connections and delays in clinical notifications. In the worst cases, devices may fail, which for manufacturers can trigger product recalls, compliance violations and an erosion of customer trust.  

With adoption rates rising, the wireless technology landscape is increasingly complicated to manage as it moves from discrete and comparatively simplistic electronic components to highly integrated modules housing multiple wireless protocols such as 5G cellular, Wi-Fi and Bluetooth® Low Energy.

Khushboo Kalyani is a LitePoint Product Manager responsible for wireless connectivity and cellular test systems. She addressed a series of questions that medical device manufacturers should be asking as they prepare test beds for their wireless products. 

Which wireless technology is best suited to my product?

Khushboo: The choice depends on how much data needs to be transferred, how swiftly and over what distance. Medical devices carrying large data volumes that require reliable, always-on connections may be better suited to Wi-Fi. These include insulin pumps and devices for monitoring blood pressure and heart rate. Others, like blood glucose monitors and pulse oximeters, transmit small amounts of data just a few times a day and may be better candidates for Bluetooth.

Cost is another important consideration, with Bluetooth modules generally adding less to bill of materials budgets than Wi-Fi or cellular modules. Designers should also familiarize themselves with compliance and regulatory requirements that may influence their connectivity decisions.

What are the different stages of wireless test and how do they differ?

Khushboo: During R&D and design verification testing, the focus typically is on validating fundamental RF parameters. These include power output, receive sensitivity and Error Vector Magnitude across different frequency bands of operation.

During quality and assurance testing, the focus shifts to the user experience. This includes validating performance across real-world use cases and conducting co-existence and over-the-air (OTA) interference testing to determine if the product will perform well in the field. It’s important to test full parametric performance and not just rely on go/no go tests that only indicate if the device is functional.

Production testing requires an optimum balance of quality and cost economics. That means checking the device’s bare minimum functional performance and then testing multiple devices simultaneously to reduce the cost of test and expedite time to market.

There are two common denominators that cut across these different test stages. The first is hardware test equipment that is capable of scaling from lab to manufacturing. The second is a user-friendly yet advanced automated software tool that reduces RF testing overhead to minimize test-suite development and design and execution times.

What is the best way to comprehensively test wireless performance?

Khushboo: As you progress through the product development cycle, what you test and the way you test will vary. When designing a product from scratch, for example, it’s important to measure the performance of the RF transceiver in isolation to ensure it meets design specifications. Once the device is validated, it must be tested in its entirety. Real-world scenario testing entails attaching the device antenna and casing to ensure the final hardware and software are not impacting wireless performance.

Can testing help ensure patient data accuracy?

Khushboo: Hospitals and home environments can be crowded RF spaces, with multiple devices operating at similar frequencies. Interference can lead to dropped signals, corrupt data or incomplete transmissions. Even a small percentage of lost or distorted data can undermine the reliability of clinical decisions. 

Interference testing that measures device sensitivity, Packet Error Rate (PER) and Bit Error Rate (BER) can indicate how often transmissions are corrupted under different conditions. Some throughput tests can also identify design flaws by measuring data transfer rates between devices on a wireless network.

Should I use an off-the-shelf RF module or design-in a chipset technology?

Khushboo: When you buy off the shelf, you typically don’t have access to the wireless chipset and controls for testing. That means you need to use the command provided by the module vendor, write your own software or rely on a test vendor like LitePoint, which has a test methodology set-up to quickly validate performance. 

The choice is contingent on two factors:

• Time to market: Off-the-shelf modules can be expensive but often reduce development time, as they come pre-certified and pre-calibrated. Generally, that eliminates time spent working with regulatory labs for compliance testing. On the other hand, commissioning a chipset design means working extensively with the chipset supplier to ensure seamless integration into your product. This can be a complicated, time-consuming process that adds overhead to the design process.

• Form factor: Chipset-based designs offer better control over the end-device form factor by accommodating smaller, compact designs compared to off-the-shelf modules.

Whether you design your chipset or buy an off-the-shelf module, LitePoint provides automation software through the IQfact+ tool that supports the gamut of chipset-specific test packages and can be used out of the box.

Are there additional test considerations when I move into high-volume device production?

Khushboo: Many medical devices sell in the hundreds of thousands or even millions of units, so the ability to scale testing is an important step for accurately determining device yield. Just as importantly, designers want to make sure they aren’t incorrectly failing good units and/or passing bad units. An inaccurate test is as harmful as no test at all.

How can device makers better manage test costs?

Khushboo: If manufacturing volumes are high and test costs are rising, you should consider a cost-of-test analysis, which includes single-test and multi-test options. This can help manufacturers reduce costs and expedite time to market by determining how much time it takes to test one device as a percentage of overall capital equipment costs compared to how long it takes to test multiple devices in parallel.

What would you like medical device manufacturers to remember on their development journey?

Khushboo: It’s clear that the healthcare community is committed to discovering and delivering wireless device technology to improve patient outcomes. LitePoint has helped hundreds of customers successfully launch wireless products over more than 25 years by adapting a combination of hardware and software test automation tools to a range of applications. If there is one word of advice I can share, it’s that accurate, repeatable, scalable testing is a key step in achieving that highest level of care.