• Your smartwatch can track a lot of things, but at least for now, it can’t keep an accurate eye on your blood pressure. • Last week researchers from University of Texas at Austin showed a way you smartwatch someday could. • They were able to discern blood pressure by reflecting radio signals off a person’s wrist, and they plan to integrate the electronics that did it into a smartwatch in a couple of years. • Beside the tried-and-true blood pressure cuff, researchers in general have found several new ways to monitor blood pressure using pasted-on ultrasound transducers, electrocardiogram sensors, bioimpedance measurements, photoplethysmography, and combinations of these measurements. • “We found that existing methods all face limitations,” Yiming Han, a doctoral candidate in the lab of Yaoyao Jia told engineers at the IEEE International Solid State Circuits Conference (ISSCC) last week in San Francisco. • For example, ultrasound sensing requires long-term contact with the skin.

Article Summaries:

  • Researchers at the University of Texas at Austin have demonstrated a non‑contact method for measuring blood pressure that could be incorporated into a smartwatch within a few years. By reflecting near‑field radio waves off the wrist, the team detected distinct phase changes in the reflected signal during systole and diastole, correlating these changes with standard cuff measurements. The prototype uses a patch antenna, a circulator, and a custom integrated circuit to transmit and receive 2.4‑GHz microwaves, enabling continuous monitoring without skin contact. This approach aims to overcome limitations of existing techniques-such as ultrasound, photoplethysmography, and bioimpedance-that can be uncomfortable, skin‑tone dependent, or require prolonged contact.
  • Researchers at the University of Texas at Austin have demonstrated a non‑contact method for measuring blood pressure that could be integrated into a smartwatch within a few years. By reflecting near‑field radio waves off a person’s wrist, the team correlated the phase and strength of the reflected signal with systolic and diastolic pressure measured by standard cuff devices. The prototype uses a wrist‑mounted patch antenna, a circulator, and a custom IC to transmit and receive 2.4 GHz microwaves, offering a skin‑tone‑independent alternative to existing cuff, ultrasound, or photoplethysmography techniques. The researchers plan to refine the electronics for consumer wearables.

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