In collaboration with Nuanic, Celltech Oy developed a custom, curved 18 mAh lithium polymer (LiPo) cell designed to fit the compact, curved shape of the smart ring.
Nuanic is a Finnish technology company developing wearable devices and software for the early detection and prevention of stress-related conditions.
The Nuanic smart ring measures the electrical conductivity of the skin, known as electrodermal activity (EDA), which can be used to monitor sympathetic nervous system activity. The measurement accuracy of Nuanic’s technology and its suitability for continuous, around-the-clock use in everyday life have been evaluated in scientific studies¹ ². The technology has also been studied in the context of early detection and prevention of burnout³.
Challenge: performance and safety within a compact design
The battery solution needed to provide long operating time, reliable performance and safety in a wearable device designed for continuous use. The battery had to meet the energy requirements of continuous measurement without compromising the size or wearability of the smart ring. A short charging time was also an important requirement.
One of the key design challenges was the battery’s compact size and curved shape. The Nuanic smart ring is available in several sizes, with inner diameters ranging from 17.1 mm to 21.2 mm. The size and shape of the battery cell therefore needed to make efficient use of the limited space available inside the ring. A conventional rectangular battery cell was not suitable for this design.
Solution: a reliable, custom LiPo battery for the smart ring
In collaboration with Nuanic, Celltech Oy developed a custom, curved 18 mAh lithium polymer (LiPo) cell. The cell was designed to fit the compact structure of the smart ring and make efficient use of the available space.
Celltech’s battery expertise and supplier network helped identify a cell manufacturer whose manufacturing process is particularly well suited to curved LiPo cells. The method helps maintain the cell’s structural integrity and reliable performance even after hundreds of charge and discharge cycles.
The curved design follows the shape of the ring, making the cell well suited to this application. The battery solution was developed with a particular focus on compact size, long operating time, reliability and safety. With the 18 mAh cell, the smart ring can operate for up to five days on a single charge, while a full charge takes approximately 30 minutes.
The solution also supports Nuanic’s aim of developing responsibly produced wearable technology and Celltech’s commitment to developing responsible battery solutions. Safety, optimal sizing and responsibility were also key considerations when selecting the battery solution.
Outcome: battery technology as part of innovative wearable technology
The collaboration between Nuanic and Celltech brings together expertise in wearable technology and custom battery solutions. The result is a compact, curved 18 mAh LiPo cell that follows the shape of the ring, supporting continuous measurement and convenient everyday use of the smart ring.
The collaboration shows how a purpose-designed battery can support the functionality of a compact wearable device, while meeting requirements for operating time, charging and reliability.
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The Nuanic smart ring and its custom curved 18 mAh LiPo cell will be on display at Alihankinta 2026 in Tampere, Finland, from 29 September to 1 October 2026. You can find Celltech in Hall D, Stand D182. Visit us to see the solution and discuss your product’s battery requirements with our specialists.
Can’t make it to the exhibition? Contact our specialists to discuss what kind of battery solution would best meet your product requirements.
Researches
¹ Torniainen et al., 2015. IEEE.
² Pakarinen et al., 2019. IEEE.
³ Salonius et al., 2024.
