Integrated PMUTs on Elastic Substrate for Wearable Applications

Hybrid electronics integration enables the development of novel wearable skin patches where conventional rigid electronics can be integrated into soft and conformal substrates. This work presents a stretchable patch with integrated piezo micro-machined ultrasound transducers (PMUTs) for potential application in continuous blood pressure estimation, as well as measuring arterial wall thickness and stiffness. The performance of the integrated PMUT is evaluated via a specific acoustic measurement setup to detect the dimensional variation of a water-filled pipe as a function of the applied pressure using pulse-echo arrival time. The setup mimics dimensional changes to arterial diameter due to blood flow. With the setup, the diameter change of 4.17 mm and wall thickness change of 0.41 mm are detected while the pipe pressure varies from 0–2 bar.