Wearables have changed markedly since they were first conceived as novelty items almost a decade ago. Exercise trackers may have brought this segment of the Internet of Things (IoT) to the consumer realm when they were first introduced, but industrial and commercial applications – even medical use cases that go far beyond just tracking wellness – are now flourishing.
According to some estimates, there will be almost 487 million wearable units in use by 2018, with a compound annual growth rate of roughly 56 percent in the years to follow. This comes as an entire generation of aging baby boomers will come to rely on wearable devices for accurate healthcare monitoring and assistance, and as Industry 4.0 brings a wealth of IoT devices into the “factory of the future,” signaling the latest major industrial revolution.
But the success of wearables hinges on their ability to remain powered while allowing users to stay mobile and active. This requires innovative and agile power management architectures and solutions that can support all of the unique capabilities that this technology promises.
Unique challenges of powering wearables
As most wearable devices require batteries, the challenges with powering them begin with form factor. These devices are meant to deliver significant capabilities while feeling almost weightless or invisible to the user. At the same time, batteries need to support the many different functions of the device. This requires a powerful management architecture that delivers optimal heat dissipation to ensure the user’s comfort alongside the ability to keep the device autonomous.
Making these requirements challenging are the bevy of power-hungry components included in most modern wearables. RF components that enable Bluetooth, Wi-Fi and GPS capabilities, for instance, are characteristic functions, by and large, of all of these devices. More sophisticated wearables are becoming increasingly common as well, needing power management systems that support LCD screens and white LEDs to backlight them, requiring a boost of voltage in most cases. Even for the already common fitness and medical tracking wearables, additional sensors that monitor heart rate will need to be accounted for in these solutions.
On the outset, most of the power management for wearable devices came from discrete components within the device. These power management schemes would require a traditional charger, along with DC-DC converter and LDO schemes within the wearable. This then evolved to the introduction of a centrally controlled power management unit within the device, with a number of critical components that use a sensor interface to communicate with this CPU that is managing all of the power inside of the wearable. In this scenario, power management is incorporated into a SoC within the wearable that allows for more agile and intuitive energy distribution.
As these devices take on more functionality in the years to come, however, power management needs to evolve further to assure the devices can stay always on. While incorporating power management into the SoC delivers maximum flexibility of distribution, the only way to continue improving efficiency and lowering heat generation in this configuration falls on the creation of lower power chip technologies that can decrease active/sleep current.
The future of wearable power management
In the short term, power management is going to be driven by the use of independent operation of the various subsystems within the device that will operate outside of the CPU. For instance, for the integration of Bluetooth low energy (BLE), a separate module subsystem will operate around its own independent processing unit, allowing the main unit to more or less operate on its own.
This gives the main CPU more intelligence to operate independently, allowing it to expend less energy and not be “always on” in the sense that it must support communication with other BLE devices. In tandem with lower-power chip designs, this will require less demanding constant power requirements in favor of selective powering of independent units only when necessary – basically allowing the device to “sleep” and “wake” intelligently.
Further down the line, however, power management will need to evolve markedly to keep up with the rate of advancement that consumers have become accustomed to with the functionality of their IoT devices. This can be done by harnessing and adapting existing functions and processes within wearables today for innovative power management down the line.
RF harvesting, for instance, is an emerging technology that looks to be ideal for wearable devices, as it harnesses the frequencies that are constantly being exchanged between the sensors and beacons that characterize wearable connectivity. It delivers uncoupled wireless charging because RF signals are common everywhere in the modern world, and components already exist within wearable devices that can collect them. In development and down the line are additional components that can convert these frequencies to energy that can essentially keep devices always-on without the need of wall-to-device charging.
This technology will make wearables the truly independent devices that both consumers and professional users will demand in the future, allowing wearables to be always responsive and, in theory, always worn. The implications will be far reaching in the industrial sector, for instance, as monitoring of different components of the assembly line will never need to be interrupted, ideally assuring more productive, safer and efficient factories in the years to come. The implications for healthcare, too, are easy to imagine, as monitors and health aids can live alongside their users with minimized risk of powering off that could harm a user’s wellbeing.
With the goal of achieving a wire-free future for wearables and all IoT devices, the possibilities for wearables in terms of size and functionality grow remarkably, making this once novel sector of the industry one of the more meaningful technologies to emerge from it.
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