# A conformal piezoelectric microsystem for demographic-adaptive and calibration-free cuffless blood pressure monitoring

## TL;DR

A new wearable device accurately tracks blood pressure without needing frequent recalibration, using a stretchable sensor and adaptive model.

## Contribution

A conformal piezoelectric microsystem with a demographic-adaptive model enables calibration-free and continuous blood pressure monitoring.

## Key findings

- The device achieves mean absolute errors of 5.22 mmHg for systolic and 4.57 mmHg for diastolic blood pressure.
- The system uses pulse wave velocity and vessel diameter measurements for accurate blood pressure estimation.
- A time decay compensation strategy improves stability during long-term use.

## Abstract

Frequent recalibration poses a significant challenge to the accuracy and reliability of current cuffless blood pressure (BP) monitoring devices, especially in long-term use. Here, we introduce a conformal and stretchable piezoelectric microsystem (CSPM) combined with a demographic-adaptive BP estimation model, enabling calibration-free, continuous BP tracking with accuracy comparable to cuff-based medical devices. The CSPM integrates an ultrasound transducer array for vessel diameter waveform recording and two pulse waveform (PWF) sensors with cavity-enhanced piezoelectric thin films for precise pulse wave detection, enabling simultaneous measurement of pulse wave velocity (PWV) and vessel diameter in the same localized vascular area. Leveraging real-time PWV and vessel diameter inputs, our BP algorithm employs a demographic feature learning module for broad population applicability and a time decay compensation strategy to address minor slippage and measurement shifts, enabling the acquisition of individual BP values without calibration. This innovation effectively addresses key challenges in population recalibration and multimodal integration, enabling stable long-term continuous BP tracking, achieving mean absolute errors of 5.22 mmHg for systolic BP and 4.57 mmHg for diastolic BP.

Frequent recalibration poses a challenge to the reliability of cuffless blood pressure monitoring devices. Here, the authors introduce a conformal and stretchable piezoelectric microsystem combined with a demographic-adaptive model, enabling calibration-free, continuous BP tracking.