Persistent clocks for batteryless sensing devices

Josiah Hester, Nicole Tobias, Amir Rahmati, Lanny Sitanayah, Daniel Holcomb, Kevin Fu, Wayne P. Burleson, Jacob Sorber

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


Sensing platforms are becoming batteryless to enable the vision of the Internet of Things, where trillions of devices collect data, interact with each other, and interact with people. However, these batteryless sensing platforms-that rely purely on energy harvesting-are rarely able to maintain a sense of time after a power failure. Thismakes working with sensor data that is time sensitive especially difficult.We propose two novel, zero-power timekeepers that use remanence decay to measure the time elapsed between power failures. Our approaches compute the elapsed time from the amount of decay of a capacitive device, either on-chip Static Random-Access Memory (SRAM) or a dedicated capacitor. This enables hourglass-like timers that give intermittently powered sensing devices a persistent sense of time. Our evaluation shows that applications using either timekeeper can keep time accurately through power failures as long as 45s with low overhead.

Original languageEnglish (US)
Article number77
JournalACM Transactions on Embedded Computing Systems
Issue number4
StatePublished - 2016


  • Batteryless
  • Clocks
  • RTC
  • Remanence timekeepers
  • SRAM

ASJC Scopus subject areas

  • Software
  • Hardware and Architecture


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