Five major design challenges faced by remote patient monitoring systems

The wearable patient monitor market is developing rapidly. Remote patient monitors help doctors monitor patients in real time, which can foresee the future of the Internet of Things in the healthcare field.

The remote patient monitoring system saves time for patients and doctors, and can provide critical patient information on an outpatient basis. Patient mobility has also become a trend. Through a secure connection to a wireless network, remote patient monitors can shorten patient visit time and avoid excessive cable interference. Today’s wearable medical products can not only measure vital signs, but can also be used as a personal emergency system. Because this is a complex terminal device, patient monitors will face five common major design challenges: power consumption (or battery life), portability (or size), patient safety, secure data transmission and integration.

Figure 1 shows the high-level block diagram of the wearable patient monitor, focusing on the battery management, non-isolated DC/DC power supply, isolation and wireless interface subsystems.

Five major design challenges faced by remote patient monitoring systems

Figure 1: High-level block diagram of a wearable patient monitor

Five challenges faced when designing a wearable patient monitor:

Battery Life

Portable and wearable patient monitors are usually battery powered. For consumers, battery life is a key factor to consider when buying. Battery life is critical because most patient monitors require continuous measurement and monitoring. The battery power supply system requires careful partitioning, strict use of space, and effective use of available power. While providing power more efficiently in a small space, it is important to achieve more functions and extend the time. Functions such as standby, sleep, power saving, hibernation and shutdown are essential to reduce power consumption and extend battery life. Wake-up time and standby power consumption also play a key role in wireless connectivity solutions.

Users can choose low-power microcontrollers (MCUs) and analog integrated circuits, but they cannot use most of the latest technologies in their designs without optimizing power management. It is very important to select the correct power architecture for the application to improve efficiency and extend battery runtime.

Most designers think that switching controllers or converters help to achieve high-efficiency power solutions, and low-loss regulators (LDOs) have poor efficiency. But LDO topologies have been gradually optimized, they can provide extremely low step-down Voltage. After improving the front-end power path of the battery charger, mid-rail DC/DC converter and LDO, load switches can still be used to reduce the shutdown current. For example, the radio MODULE may consume more than 10 μA in deep sleep or hibernation mode. The load switch can reduce the shutdown current to only 10 nA (see Figure 2).

Figure 2: Adding a low-leakage load switch to reduce the shutdown current

Portability or size

Devices such as heart rate monitors, multi-parameter patches, continuous blood glucose monitors, handheld pulse oximeters, fitness monitors, and activity monitors can be portable and wearable types. Many of these devices are disposable devices, or need to replace the battery, so the overall form requirements are very strict.

The selection of battery types and charger devices; the selection of buck, boost or buck-boost converters; the package selection of wireless (or radio frequency) equipment, all of which help reduce the size of the product.

At present, there are some new technology applications that integrate crystals inside wireless MCUs. TI bulk acoustic wave (BAW) technology can eliminate the external crystal footprint of the printed circuit board (PCB), thereby reducing layout size and simplifying layout. Improvements in packaging technology can also help achieve more integration and save space.

For remote patient monitoring systems, TI BAW technology can provide reliable and real-time patient vital data transmission through a secure wireless network.

Patient safety

Patient safety is a priority for global healthcare. The portable multi-parameter patient monitor can measure vital signs, and use digital isolators and isolated power supplies to isolate data and power to achieve patient safety. The key design challenges associated with isolated power supplies 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 through reinforced isolation.

Secure data transmission

Medical sensor patches and portable patient monitors with wireless connectivity require top-notch security. The patient data transmitted to the nurse’s station or doctor’s office is proprietary information, and preventing data theft is a very critical aspect.

A variety of security measures can protect intellectual property (IP) and data between patients and doctors. These measures should support the prevention of attacks and ensure the safety of patient data transmission, not only when processing and converting to vital signs parameters for Display, but also during transmission. This is called wireless security.

integrated

The development time of medical patient monitors is critical, because the time to market involves many standard laboratory tests and approvals (globally). By realizing the connection with various cloud providers, the data transmission of the family patient monitoring system can be realized with minimal integration workload, and the patient data can be directly uploaded to the cloud, which can save the space of the on-board memory card.

Code compatibility between platforms such as Bluetooth?, Bluetooth Low Energy and Wi-Fi? can reduce the number of repeated code attempts. The integration of multi-core, universal asynchronous receiver/transmitter, interface standards and multiple universal input/output provides support for various system-level requirements and ready-made interfaces, while also completing docking with other processors.

in conclusion

The next big wave of medical patient monitors will come with extremely small sizes. As the problems of wearable devices and remote patient monitors are solved, and higher-quality devices (smaller and more connected) are brought to the market at a lower and more affordable price, the medical community will witness the adoption of new patches. Adopt quickly. From hospitals in developed countries to telemedicine centers in developing countries to diagnosis of wounded soldiers on the battlefield, the rapid development of wearable devices is changing the medical environment and helping to provide better diagnosis and treatment.

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