A Microfabricated Nanobubble-Based Sensor for Physiological Pressure Monitoring

A microfabricated nanobubble-based sensor was developed for real-time physiological pressure monitoring. The fully immersed sensor utilizes an electrolytic bubble generated and localized within a microfluidic channel that is in communication with the local environment. Bubble size varies with local pressure changes, allowing pressure to be monitored by tracking the resulting electrochemical impedance changes. An asymmetric electrode pair bubble generator design achieved precise picoliter-volume bubble control using either oxygen or hydrogen gas. Precise pressure monitoring down to a resolution of 1 mmHg (0.13-kPa) was achieved using long-lasting (>4 hours) oxygen bubbles tracked under a quasi-stable regime bounded by distinct, traceable bubble-channel wall detachment interac- tions. This corresponds to a $20\times $ improvement in resolution compared to microbubble-based pressure sensors reported to date. [2023-0077]