A 0.065-mm 3 Monolithically-Integrated Ultrasonic Wireless Sensing Mote for Real-Time Physiological Temperature Monitoring

C. Shi, T. Costa, J. Elloian, Y. Zhang, K.L. Shepard

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)
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Accurate monitoring of physiological temperature is important for many biomedical applications, including monitoring of core body temperature, detecting tissue pathologies, and evaluating surgical procedures involving thermal treatment such as hyperthermia therapy and tissue ablation. Many of these applications can benefit from replacing external temperature probes with injectable wireless devices. Here we present such a device for real-time in vivo temperature monitoring that relies on 'chip-as-system' integration. With an on-chip piezoelectric transducer and measuring only 380 μm × 300 μm × 570 μm, the 0.065-mm 3 monolithic device, in the form of a mote, harvests ultrasound energy for power and transmits temperature data through acoustic backscattering. Containing a low-power temperature sensor implemented with a subthreshold oscillator and consuming 0.813 nW at 37 °C, the mote achieves line sensitivity of 0.088 °C/V, temperature error of +0.22/-0.28 °C, and a resolution of 0.0078 °C rms. A long-term measurement with the mote reveals an Allan deviation floor of <138.6 ppm, indicating the feasibility of using the mote for continuous physiological temperature monitoring.

Original languageEnglish
Article number8979270
Pages (from-to)412-424
Number of pages13
JournalIEEE Trans Biomed Circuits
Issue number3
Publication statusPublished - 2020


  • Backscattering
  • monolithic integration
  • temperature sensor
  • ultrasound
  • wireless sensing system


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