Continuous monitoring of vital signs has become increasingly important for digital healthcare and enhancing self-awareness. Wearable devices like smartwatches, earbuds, and rings are gaining widespread acceptance for health monitoring. However, two significant challenges remain: (i) the limited battery life of these devices makes them unsustainable for long-term use, and (ii) many older adults, who would benefit most from health monitoring, often face barriers due to limited digital literacy. To address these issues, we introduce BioPulse---a perpetual, patch form-factor device designed for continuous monitoring. BioPulse estimates key parameters for cardiac health such as heart rate, heart rate variability, and blood pressure. By utilising a sparse sampling algorithm alongside NFC-based energy transfer and communication, the system operates without a battery, achieving a 57.9% reduction in power consumption. The system demonstrates a mean absolute error of 5.6 mmHg for systolic blood pressure (SBP) and 4.5 mmHg for diastolic blood pressure (DBP) compared to the ground truth device. This combination ensures a more sustainable and accessible solution for vital signs monitoring.@en

Continuous vital sign monitoring is essential for digital healthcare and self-awareness but is hindered by the limited battery life of wearable devices and barriers faced by older adults with low digital literacy. BioPulse, a battery-free patch device, addresses challenges in vital sign monitoring by using sparse sampling and NFC energy transfer to track heart rate, HRV, and blood pressure.@en