Could implantable body flow sensors be self-powered?

The rise of Smart Health has led to implantable healthcare devices that can diagnose and monitor diseases in real-time. Some diagnoses are based on fluids in the body: reduced lung flow may indicate an asthma attack, and high turbulence in the blood may indicate hemolysis. A key challenge of current `implantables’ is that they are difficult to power and require iterative surgeries to replace batteries. Here we show that a piezoelectric flow sensor could monitor a fluid flow and power itself from the same flow at the same time. The effectiveness of this dual-purpose sensor/harvester depends on flow properties. A sensor that measures flowrate needs a different duty cycle than one that measures subtle abnormalities, such as turbulent wakes caused by inflammation. In the human airway, a sensor could use bidirectional airflow to create an oscillating voltage directly. In unidirectional artery flow, sensing/harvesting depends on complex fluid-structure interactions like flutter. This variation allows a breadth of applications, but it also demands advanced models that capture the tradeoffs between sensing fidelity and harvesting potential. To develop these models, we built a platform for testing the sensing/harvesting capability of piezocantilevers in bio-inspired oscillating flows.