As medical device companies continue to innovate and introduce new bioelectronic device capabilities, new possibilities and needs have emerged for every element of medical device design and manufacturing. Better technology enables new devices not previously possible, and improved versions of existing medical devices, to treat chronic conditions like heart failure, chronic pain, depression, epilepsy, and more, and to improve patient outcomes.
Two areas of improvement for every medical device designer to consider are:
1. The size and comfort of the medical device
2. The device’s run time
Because patient preference is driven by how easy a device is to use and how little it interferes with their daily activities, we’re sharing 7 ways you can maximize your medical device’s run time while keeping it small and comfortable for patients.
Background
We have worked with several medical device companies who have removed their implanted battery completely and are using continuous wireless power to enable the implant’s functionality. That functionality can be delivering electrical stimulation as part of therapy delivery, such as for a sleep apnea stimulator, transmitting critical data out from the body, such as for a brain-computer interface, both, or something else altogether. We’ve also worked with medical device companies whose devices consume high power levels, exceeding 10 Watts. Improving their device’s efficiency is almost always a top priority.
Oftentimes, we hear from medical device designers who are focused on improving their device’s power management and efficiency to reduce heat generation and meet the FDA’s strict thermal requirements for implanted medical devices. However, while a medical device’s design affects both performance metrics, efficiency and tissue heating are not the same.
Tissue heating must be limited for patient safety and to meet regulatory requirements; however, a low power device could meet FDA requirements for limited temperature rise without maximizing power efficiency. Without maximizing power efficiency, a device could require more frequent charging or a larger battery than needed, as two examples, and the patient experience would be negatively affected. A device has to be optimized for both minimal heat generation and high efficiency power management to deliver the best patient experience.
So, how can medical device designers limit temperature rise and optimize their entire device for high efficiency power management? Designers should start by focusing on maximizing run time while minimizing batteries.
7 Ways to Improve Medical Device Run Time
Optimizing medical devices for long run times while using the smallest possible battery involves a combination of efficient design, power management strategies, and technological advancements.
Here are 7 ways medical device designers can achieve long run times while miniaturizing their device and its battery/batteries:
1. Energy-efficient design
Medical device efficiency is affected by several parts of a device, including the wireless power system coils, external controller and implanted electronics, and controls and communications system. Designing the device components to operate with minimal power consumption is crucial. This includes using low-power microcontrollers, sensors, and other electronic components to off load high frequency tasks to peripherals or analog circuitry.
2. Use high-Q coils
Typically, the part of a medical device that consumes the most power is the wireless power link, or the components directly involved in wirelessly transferring and receiving power. A higher-Q or higher quality coil will deliver a longer run time for a device regardless of the size and type of battery.
3. Battery selection
Choosing the right type of battery is essential. Lithium-based batteries, such as lithium-ion (Li-ion) or lithium-polymer (LiPo) batteries offer high energy density compared to other types of batteries. They are also lightweight, making them suitable for portable medical devices. Solid-state batteries are another good option for very small medical devices as their stacked architecture and high energy density enable even smaller batteries with comparable performance to lithium-ion batteries for medical devices.
4. Avoid LDOs
LDOs are linear and low dropout voltage regulators. A LDO is designed to regulate a voltage by turning excess power into heat. LDOs are easy to implement, but consume a lot of energy. Instead, there are other DC/DC converters that are small and very efficient.
5. Power-saving modes
Incorporating power-saving modes can extend battery life significantly. For instance, devices can have sleep modes or low-power states that activate when the device is idle. Additionally, components that are not essential for basic functionality can be temporarily powered down.
6. Efficient algorithms
Developing algorithms that require minimal computational power can reduce energy consumption. This is particularly relevant for devices that perform data processing or analysis. Optimization techniques such as algorithmic simplification or hardware acceleration can help achieve this goal.
7. Wireless communication optimization
If the device incorporates wireless communication capabilities (e.g., Bluetooth, Wi-Fi), optimizing communication protocols and transmission intervals can reduce power consumption. Using low-energy protocols such as Bluetooth Low Energy (BLE) can be beneficial. Even better, using power-link-integrated communications and controls such as Resonant Link uses ensures you don’t have to have a bluetooth antenna, which means you can shrink your device even more, and optimizes the power consumption to conserve energy. Resonant Link can wirelessly deliver 100 kbps of data over the power-link with no additional power consumption.
By implementing these strategies, medical device designers and manufacturers can create devices with longer run times while utilizing smaller batteries both inside and outside of the body, enabling high performing active implants and passive implants with no implanted battery at all. In both situations and whatever a device’s power needs, optimizing their medical device design and power management for both high efficiency and low heat generation ensures an optimal user experience without sacrificing the effectiveness of the device.
