This technology is a smartwatch-compatible, low-power wearable that uses radio frequency bioimpedance and AI to continuously and non-invasively monitor blood pressure, offering accurate, skin color-independent readings and robust performance compared to traditional optical sensors.
Background
Blood pressure (BP) monitoring is a cornerstone of cardiovascular health management, as hypertension is a leading risk factor for heart disease, stroke, and other serious conditions. Traditionally, BP is measured intermittently using inflatable cuffs, which can be uncomfortable and impractical for continuous monitoring. The growing prevalence of wearable health devices, such as smartwatches, has driven demand for non-invasive, continuous BP monitoring solutions that are comfortable, unobtrusive, and suitable for everyday use. Continuous BP monitoring can provide valuable insights into an individual’s cardiovascular health, enable early detection of hypertension, and support personalized healthcare interventions. As such, there is a significant need for wearable technologies that can deliver accurate, reliable, and equitable BP measurements across diverse populations.
Current approaches to wearable BP monitoring predominantly rely on photoplethysmography (PPG), an optical technique that estimates BP by analyzing blood volume changes in the microvascular bed of tissue. However, PPG-based systems face several critical limitations. Their accuracy is often compromised in individuals with darker skin tones due to reduced optical penetration and weaker light-artery interactions, leading to biased readings and inequitable healthcare outcomes. Additionally, PPG sensors are highly susceptible to motion artifacts, which can distort measurements during daily activities and reduce reliability. Integration of PPG sensors into wearable devices also requires precise alignment and intimate skin contact, which can be uncomfortable and limit user compliance. These challenges highlight the need for alternative, robust, and equitable BP monitoring methods that can overcome the shortcomings of current optical and contact-based technologies.
Technology Description
This technology is a smartwatch-integrable, low-power wearable system designed for continuous, non-invasive blood pressure monitoring using radio frequency (RF) bioimpedance and artificial intelligence. By repurposing a standard inverted F-type Wi-Fi antenna from a commercial smartwatch and mounting it on a 3D-printed nylon substrate within a watch strap, the system operates in a non-contact manner to measure the reflection parameter (S11) of an RF signal at the tissue-artery interface. This allows it to detect changes in arterial bioimpedance, which correlate with blood flow and blood pressure. The system extracts both frequency and time-domain features from these bioimpedance signals and processes them with an AdaBoosted Decision Tree regressor to estimate systolic and diastolic blood pressure. The approach is robust to variations in skin color, less susceptible to motion artifacts than optical methods, and is easily integrated into existing smartwatch infrastructure, achieving accuracy comparable to medical-grade photoplethysmography (PPG) sensors and meeting BHS/AAMI standards.
What differentiates this technology is its unique combination of RF bioimpedance sensing and AI-driven analysis, which overcomes significant limitations of current wearable blood pressure monitors, particularly those relying on PPG. Unlike PPG, which can be biased by skin pigmentation and is sensitive to motion, this RF-based solution provides equitable, reliable measurements across diverse populations and in real-world conditions. Its non-contact design enhances user comfort and device durability, while leveraging existing smartwatch hardware simplifies manufacturing and integration, reducing cost and complexity. Preliminary studies demonstrate that its accuracy rivals medical-grade devices, with mean absolute errors well within clinical standards. The platform’s adaptability to other wearable forms, such as rings, and its potential for broader health monitoring applications—ranging from stress and mood detection to pharmaceutical studies—further distinguish it as a transformative advancement in wearable health technology.
Benefits
- Continuous, non-invasive blood pressure monitoring integrated into a smartwatch form factor
- Robust to skin color variations, eliminating bias common in optical PPG-based devices
- Non-contact measurement enhances user comfort and reduces need for precise sensor placement
- Lower power consumption suitable for wearable, continuous monitoring
- Reduced susceptibility to motion artifacts compared to optical and radar methods
- Utilizes existing smartwatch Wi-Fi antennas for simplified integration and reduced system complexity
- Achieves clinically relevant accuracy meeting BHS and AAMI standards
- Potential for expansion to other health monitoring applications such as stress, hydration, and pharmaceutical effects
Commercial Applications
- Continuous blood pressure monitoring
- Remote hypertension management
- Equitable health tracking wearables
- Population health analytics
- Pharmaceutical effect monitoring
Additional Information
This wearable system continuously monitors blood pressure non-invasively. It repurposes a smartwatch Wi-Fi antenna to measure radio frequency bioimpedance (S11) at the tissue-artery interface. Extracted frequency and time-domain features from these signals are processed by an AdaBoosted Decision Tree regressor to estimate systolic and diastolic BP. This RF-based approach offers robustness to skin color and motion artifacts.
Intellectual Property
PCT/US2025/039271
