Five design issues for telemedicine patient monitoring systems

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Five design issues for telemedicine patient monitoring systems [Copy link]

The wearable patient monitor market is growing rapidly. Remote patient monitors help doctors monitor patients in real time, which foresees the future of IoT in healthcare.

Remote patient monitoring systems save time for patients and doctors, providing critical patient information on an outpatient basis. Patient mobility has also become a trend, and remote patient monitors can shorten patient visits and avoid the interference of too many cables through secure connections to wireless networks. Today's wearable medical products can not only measure vital signs, but also serve as personal emergency response systems. 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 a high-level block diagram of a wearable patient monitor, focusing on subsystems such as battery management, non-isolated DC/DC power supply, isolation, and wireless interface.

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

Here are five challenges and solutions for designing a wearable patient monitor:

Battery Life

Portable and wearable patient monitors are typically powered by batteries. For consumers, battery life is a key purchasing consideration. Battery life is critical because most patient monitors require continuous measurement and monitoring. Battery-powered systems require careful zoning, strict use of space, and efficient use of available power. It is important to enable more functionality and longer time while delivering power more efficiently in a small space. Features such as standby, sleep, power save, 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 for wireless connectivity solutions.

Users can choose 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 your application to improve efficiency and extend battery run time.

Most designers think that switching controllers or converters contribute to an efficient power solution, while low-loss regulators (LDOs) have poor efficiency. However, LDO topologies have been gradually optimized, and they can provide very low step-down voltages. After improving the front-end power path of battery chargers, mid-rail DC/DC converters, and LDOs, load switches can still be used to reduce shutdown current. For example, a radio module may consume more than 10 A in deep sleep or hibernation mode. A load switch can reduce the shutdown current to only 10 nA (see Figure 2).

Figure 2: Adding a low-leakage load switch reduces shutdown current

Portability or size

Devices such as heart rate monitors, multi-parameter patches, continuous glucose monitors, handheld pulse oximeters, fitness monitors, and activity monitors can be portable and wearable. Many of these devices are disposable or require replacement batteries, so the overall form factor is critical.

The selection of battery type and charger unit; the selection of buck, boost or buck-boost converters; and the selection of packaging for wireless (or RF) devices all help reduce the size of the product.

There are some new technologies that integrate crystals inside wireless MCUs. TI bulk acoustic wave (BAW) technology eliminates the external crystal footprint on the printed circuit board (PCB), reducing layout size and simplifying layout and routing. Improvements in packaging technology can also help achieve more integration and save space.

For remote patient monitoring systems, TI BAW technology provides reliable, real-time transmission of patient vital data over secure wireless networks.

Patient Safety

Patient safety is a global healthcare priority. Portable multi-parameter patient monitors can measure vital signs and achieve patient safety by isolating data and power using digital isolators and isolated power supplies, respectively. Key design challenges associated with isolated power and data include output regulation, feedback mechanisms, input voltage range, output power and size considerations, and appropriate power architecture. Many newer isolated power modules, such as the small UCC12050 DC/DC converter from Texas Instruments, can support 500 mW of output power with reinforced isolation.

Secure data transmission

Medical sensor patches and portable patient monitors with wireless connectivity require best-in-class security. Patient data delivered to the nurse’s station or doctor’s office is proprietary information and preventing data theft is a critical aspect.

Various security measures can protect intellectual property (IP) and data between patients and doctors. These measures should support the prevention of attacks and ensure the security of patient data transmission, not only when it is processed and converted into vital sign parameters for display, but also during transmission. This is called wireless security.

integrated

Development time is critical for medical patient monitors, as time to market involves a lot of standard laboratory testing and approvals (worldwide). By enabling connectivity to various cloud providers, data transfer from home patient monitoring systems can be achieved with minimal integration effort, and uploading patient data directly to the cloud can save space on onboard memory cards.

Code compatibility between platforms such as Bluetooth, Bluetooth Low Energy, and Wi-Fi reduces code iteration. Integration of multiple cores, UARTs, interface standards, and multiple general purpose inputs/outputs supports a variety of system-level requirements and readily available interfaces while also interfacing with other processors.

in conclusion

The next big wave of medical patient monitors will come in very small form factors. As wearable and remote patient monitor challenges are solved and better devices (smaller in size and with connectivity) are brought to market at lower, more affordable prices, the medical community will see rapid adoption of new patches. 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 healthcare environment and helping to provide better diagnosis and treatment.

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The wearable patient monitor market is developing rapidly, which can help doctors monitor patients remotely in real time, and the prospects are endless!