“The market for wearable patient monitors is growing rapidly. Remote patient monitors help doctors monitor patients in real-time, envisioning the future of IoT in healthcare.
Author: Sanjay Pithadia
Systems Engineer, Medical Field, Systems Engineering and Marketing
The market for wearable patient monitors is growing rapidly. Remote patient monitors help doctors monitor patients in real-time, envisioning the future of IoT in healthcare.
Remote patient monitoring systems save time for patients and physicians by providing critical patient information on an outpatient basis. Patient mobility has also become a trend, with a secure connection to a wireless network, remote patient monitors can shorten patient visits and avoid the distraction of excessive cables. Today’s wearable medical products not only measure vital signs, but also serve as personal emergency response systems. Because this is a complex end device, patient monitors face five common major design challenges: power consumption (or battery life), portability (or size), patient safety, secure data transfer, and integration.
Figure 1 shows a high-level block diagram of a wearable patient monitor, focusing on subsystems such as battery management, non-isolated DC/DC power, isolation, and wireless interfaces.
Figure 1: High-level block diagram of a wearable patient monitor
Top five challenges when designing a wearable patient monitor:
Portable and wearable patient monitors are often battery powered. For consumers, battery life is a key factor to consider when purchasing. Battery life is critical as most patient monitors require continuous measurement and monitoring. A battery-powered system requires careful zoning, strict use of space, and efficient use of available power. It is important to achieve more functionality, for extended periods of time, while delivering power more efficiently in a small space. Features such as standby, sleep, power saving, hibernation and shutdown are critical to reducing power consumption and extending battery life. Wake-up time and standby power consumption also play a key role in wireless connectivity solutions.
Users can choose from low-power microcontrollers (MCUs) and analog integrated circuits, but they cannot take advantage of most of the latest technologies in their designs without optimizing power management. It is important to choose the right power architecture for an application to increase efficiency and extend battery runtime.
Most designers consider switching controllers or converters to be helpful in achieving an efficient power supply scheme, while low-loss regulators (LDOs) are poorly efficient. But LDO topologies have been optimized to provide extremely low step-down voltages. After improving the front-end power paths for battery chargers, mid-rail DC/DC converters, and LDOs, load switches can still be used to reduce shutdown currents. For example, a radio module may consume more than 10 µA in deep sleep or hibernate mode. A load switch reduces the shutdown current to only 10 nA (see Figure 2).
Figure 2: Adding a low leakage load switch to reduce shutdown current
Portability or size
Devices such as heart rate monitors, multiparameter patches, continuous glucose monitors, handheld pulse oximeters, fitness monitors, and activity monitors can be of the portable and wearable type. Many of these devices are disposable or require battery replacement, so the overall form factor is strict.
Selection of battery type and charger unit; selection of buck, boost or buck-boost converters; packaging selection of wireless (or RF) equipment, all of which help reduce product size.
There are some new technology applications that integrate crystals inside wireless MCUs. TI’s bulk acoustic wave (BAW) technology eliminates the external crystal footprint of the printed circuit board (PCB), reducing layout size and simplifying layout. Improvements in packaging technology can also help enable more integration and save space.
For remote patient monitoring systems, TI BAW technology provides reliable, real-time transmission of patient vital data over a secure wireless network.
Patient safety is a global healthcare priority. Portable multi-parameter patient monitors can measure vital signs, isolate data and power using digital isolators and isolated power, respectively, for patient safety. Key design challenges related to isolated power and data include output regulation, feedback mechanisms, input voltage range, output power and size considerations, and proper power architecture. Many newer isolated power modules, such as Texas Instruments’ small UCC12050 DC/DC converter, can support 500 mW of output power with reinforced isolation.
secure data transfer
Medical sensor patches and portable patient monitors with wireless connectivity require best-in-class security. Patient data delivered to a nurse’s station or doctor’s office is proprietary information and preventing data theft is a very critical aspect.
Multiple security measures protect intellectual property (IP) and data between patients and physicians. These measures should support attack prevention and secure transmission of patient data, not only during processing and conversion to Display vital sign parameters, but also during transmission. This is called wireless security.
Development time for medical patient monitors is critical because time-to-market involves many standard laboratory tests and approvals (on a global scale). By realizing the connection with various cloud providers, the data transmission of the home patient monitoring system can be realized with the minimum integration workload, and the patient data can be directly uploaded to the cloud, which can save the space of the onboard memory card.
Code compatibility between platforms such as Bluetooth®, Bluetooth Low Energy, and Wi-Fi® reduces code retry attempts. Integration of multi-core, UART, interface standards, and multiple general-purpose inputs/outputs provides support for a variety of system-level requirements and ready-made interfaces, while also interfacing with other processors.
The next big wave of medical patient monitors will come in tiny sizes. As the challenges of wearables and remote patient monitors are solved, and higher-quality devices (smaller in size and with connectivity) are brought to market at lower, more affordable prices, the medical community will witness the new patch being adopted Adopt quickly. From hospitals in developed countries to telemedicine centers in developing countries to diagnosing wounded soldiers on the battlefield, the rapid development of wearable devices is changing the medical environment and helping to provide better care.