A novel pressure transducer concept is introduced in which external pressure variations induce changes in the volume of a trapped microbubble ( $\mu \text{B}$ ) in an electrolyte solution. These volumetric changes are monitored by electrochemical impedance-based measurements and may be used for pressure tracking applications. Microbubbles are nucleated on-demand by electrolysis within a confinement chamber with high precision (measured size RSD $\sim 1$ %). This pressure transducer concept was developed specifically for operation in liquid environments and features biocompatible construction, small footprint (<0.1 mm2), and low power consumption (<1 nW). This combination of features is ideal for in vivo pressure monitoring applications. [2015-0203]