The rocky road to power wearables

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The market for medical wearables is booming, along with the increase in digital health applications, as more people can monitor their health from home.

Smart wearable patches require unobtrusive and small sources of power to operate. These sources also need to be flexible, which can be a challenge. However, the tech for flexible batteries is improving fast.

Rechargeable batteries are one of the promising ways forward for the new flexible battery tech. Rechargeable battery technologies include Li-polymer (LiPo) batteries, which allow for flexible battery designs that can be moulded to small wearables.

Safety and flexibility through standards

Many international standards help specify the safety and efficiency of these technologies, starting with the safety and performance of Li-ion batteries, which are the most used for wearables. For example, IEC 63370 ensures the safety of Li-ion batteries and charging systems.

Many standards relating to sensors are extensively used in wearables. For example, IEC 62951-2, which deals with flexible and stretchable semiconductor devices.

The challenges for energy harvesting

Energy harvesting for wearables is generating quite a big buzz. Whether energized by body motion, heat, or sweat, self-powered devices have attracted a lot of attention from the scientific community. The benefits are obvious: there is no need for any battery, whether big or small, and using the human body as a source of power appears to be especially environmentally friendly.

But researchers are struggling to be able to meet the energy demands of existing wearable applications using energy harvesting techniques. Low energy levels, low energy efficiency and frequent power interruptions are challenges that need to be overcome.

Piezoelectric vibration energy harvesting is the preferred method for use with wearable devices. IEC 62830-1 includes methods for evaluating the performance of vibration-based piezoelectric energy harvesting devices.

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