Micro hydraulic pressure sensing stent

This paper reports both the novel configuration and the operation principle of a pressure sensing stent (medical mesh tube) that (1) completely incorporates a micro pressure sensor into the stent wire structure and (2) achieves 75 times amplification in output signals of capacitive sensing via micro-scale hydraulic movement. A fabrication method was developed for wafer-level manufacture of the `on-wire´ pressure sensors, by grafting and processing multiple wires onto a silicon wafer. The fabricated pressure sensor on a stent successfully (1) detected the full cardiovascular pressure range of 60~260mmHg with a resolution of 0.24μm/mmHg; (2) produced 114fF of capacitive signal outputs, which is x75 times amplified compared to conventional measurement without hydraulic mechanism; and (3) demonstrated a frequency-based-sensing resolution of 0.4 kHz/mmHg at a resonance of 13.89MHz. The fabricated on-wire sensor held a tiny footprint of 8000×100μm², engraved on a 260μm-diameter copper wire, still enabling measureable outputs.