Blood Pressure Measurement via Electrical-Double-Layer Transfer Current on Tantalum/Liquid Interface

Blood pressure measurement is important for diagnosis and treatment of pressure-related chronic diseases. To meet this need, this study proposes a novel method to accurately measure blood pressure using electrical-double-layer (EDL) transfer current on tantalum/liquid interface, with self-powered sensing capability. Biocompatible tantalum is in direct contact with liquid to sense blood pressure without encapsulation, offering advantages of easy miniaturization and high sensitivity. EDL transfer current on tantalum/liquid interface is sensitive to change in flowing liquid pressure, due to pressure affecting EDL charge transfer rate. Experimental results show that it has a measurement sensitivity of 2.53 ± 0.15 nA/kPa (0.34 ± 0.02 nA/mmHg) at a peak-to-peak pressure range of 0.18 kPa (13.5 mmHg) to 15.23 kPa (114.23 mmHg) in blood-simulating fluid. Notably, this method demonstrates robustness against variations in initial pressure, vascular elasticity, heart rate, and osmolality. Transfer current is stable over the range of blood pressure fluctuations during 2000 cycles, with an amplitude of 13.17 nA. Also, feasibility of directly utilizing EDL transfer current on tantalum vascular stent-liquid interface for blood pressure measurement is preliminarily proved. In conclusion, blood pressure measurement via EDL transfer current on tantalum/liquid interface is a promising method with high stability, accuracy and repeatability, as well as easy miniaturization and self-powered sensing capability.