There is a new technology that captures the market of the future. As we all know, wearable devices are portable systems that contain sensors for collecting measurement data from our bodies. Flexible batteries are needed to power these sensors without wires, and these batteries can adapt to specific materials and provide the power required by the system. The microbattery developed by the Fraunhofer Institute for Reliability and Micro-Integration IZM provides the technological foundation for this new technology trend.
In the medical field, wearable devices are used to collect data and not interfere with patients' daily lives, such as recording long-term electrocardiograms. Because the sensor is lightweight, flexible, and hidden in clothing, this is a convenient way to monitor the patient's heartbeat. The technology has more everyday applications, such as fitness bands, which measure the pulse of a jogger while running. The market value-added potential of wearable devices is huge, and it is expected to reach a market value of 72 billion euros by 2020.
How to power these smart accessories is a major technical challenge. There are technical considerations such as durability and energy density, as well as material requirements such as weight, flexibility and size, which must be combined with each other. This is where the Fraunhofer IZM Institute comes in: Experts from the Institute have developed a prototype smart wristband that literally collects data directly. The technical part of the silicone band is its three shiny green batteries. These batteries have a capacity of 300 mAh and provide power to the wristband. They can store 1.1 watt-hours of energy and lose less than 3% of their charging capacity each year. With these parameters, the new prototype has higher capacity than the smart band currently available on the market, enabling it to power demanding portable electronic devices. In fact, the available capacity is enough to make the traditional smart watch run without loss. With these types of statistics, this new prototype device beats mature products such as smartwatches, where the battery is built into the case, not the strap.
Interdigitated electrodes for millimeter-level lithium-ion batteries
Image credit: Fraunhofer IZM, Volker Mai
Successful segmentation
Fraunhofer IZM's RF & Smart Sensor Systems researcher Robert Hahn explains why segmentation is the secret of success: "If your battery is extremely flexible, its energy density will be very poor, so segmentation is a much better way ".
The institute no longer makes batteries extremely flexible at the expense of energy density and reliability, but instead focuses on very compact, powerful batteries and optimized mounting technology. The battery is flexible between sections. In other words, the smart bracelet is flexible, while retaining more power than other smart bracelets on the market.
Segmented stripes of mechanical flexible microbattery
Image credit: Fraunhofer IZM
Customized solutions
When developing batteries for wearable devices, the Fraunhofer IZM Institute combines new methods and years of experience with customer-specific development processes: "We work with companies to develop the right batteries for them," explains a graduate electrical engineer. The team consults closely with customers to develop energy requirements. They carefully adjust parameters such as shape, size, voltage, capacity, and power, and combine them to form a power concept. The team also conducted customer-specific tests.
Smart plaster measuring sweat method
In 2018, the institute began researching a new wearable technology, smart plaster. Along with Swiss sensor maker Xsensio, this Euponsored project aims to develop a plaster that can directly measure and analyze patient sweat. It can then be used to draw conclusions about a patient's general health. In any case, having a convenient, real-time analysis tool is the ideal way to better track and monitor the healing process. Fraunhofer IZM develops the design concept and energy supply system for sweat measurement sensors. The system is integrated with a very flat, lightweight and flexible sensor. This requires the development of new concepts. For example, one idea is a packaging system made of aluminum composite foil. Researchers also need to ensure they choose materials that are inexpensive and easy to handle. After all, plaster is a disposable product.