High Resolution Nanobubble-Based Pressure Sensor for in Vivo Monitoring

A high-resolution Parylene-based pressure sensor with nanobubbles generated, localized, and monitored in realtime was tailored for in vivo monitoring. Using an asymmetric electrode pair, precise picoliter-volume oxygen bubbles were electrolytically generated and confined within an open microchannel configured for electrochemical impedance monitoring. Long-lasting (>4 hours) oxygen bubbles were coupled to a digital pressure source and an optical bubble tracking system to achieve a resolution of 1 mmHg (0.13 kPa). This resolution meets accuracy requirements for monitoring intracranial pressure (ICP), with a 0–20 mmHg range. The 20× resolution improvement corresponds to the best performance for a microfabricated bubble-based pressure sensor to date.