Battery-capacitor hybrid to power wearables

Battery-capacitor hybrid to power wearables

Addressing what it sees as a gap in the range of available energy storage solutions, Murata has developed the UMAC, a small, high-capacity cylinder-type energy device for use in wearable and wireless sensor applications that, while lithium-ion based, is being differentiated from a battery.
By eeNews Europe


The UMAC is a miniature device with a high energy storage capacity, low internal resistance, fast charging and discharging capability, and the ability to withstand load fluctuations. It may be used as a secondary battery in the same way as a capacitor, but achieves better charge/discharge characteristics and has an extended cycle life that the company says is superior to conventional batteries.

Suited for use as a power supply for wearable devices or sensor nodes for wireless sensor networks, the UMAC maintains flat voltage characteristics while accommodating a wide range of load characteristics. Because of its small capacity and use of chemically stable materials, thermal runaway does not occur, meaning that smoke or fire will not occur in the event of a short circuit.

The UMAC is capable of 10 cycles per hour with a maximum discharge rate of 30 mA. It also features an extended cycle life with a capacity recovery rate of 90% or higher after 1,000 cycles.

The UMAC is particularly suitable as an energy device for sensor nodes within wireless sensor networks because high-rate discharge characteristics mean that peak-assist capacitors are not required. Low self-discharge level minimizes loss of stored energy, and flat voltage characteristics permit use immediately after charging starts for stable device operation.

Another application is as a power supply for digital pens or wearable devices because of its long cycle-life characteristics – enabling repeated use after rapid charging – and chemically stable composition, which allows small size and safe packaging. Other uses include backup power supply for electric home appliances and electronic devices such as mobile phones and information terminals.

UMAC Series energy device information page
Application Note for Energy Harvesting System (UMAC Series) (PDF)

Murata Electronics: