Wireless sensor networks that use energy-harvesting techniques for their power requirements are becoming increasingly common. To power such sensor circuits an “energy reservoir” is required that is compact, but still has a high capacity, a long service life (maintenance free) and a low internal resistance, and is capable of being charged and discharged rapidly.

With all these requirements in mind, Murata developed in October 2015 the UMAC, a cylindrically shaped module for energy-storage, with excellent charge/discharge characteristics and a life expectancy that is much longer than that of conventional secondary (rechargeable) batteries. This component appears to be is a cross between a battery and a capacitor, but Murata has revealed very little about its internal construction.

Because of the great market demand, Murata have now developed the UMAL, a flat version of the UMAC with a higher capacity. This component, measuring 21x14x2 mm, has a capacity of 12 mAh and a nominal operating voltage of 2.3 V. Its internal resistance is only 200 mOhm and the capacity after even 5,000 charge/discharge cycles is still more than 90% of the nominal value.