Improving the sensing capabilities of miniaturized probes nanofabricated on the tip of optical fibers is crucial for a large number of sensing applications in remote and harsh environ-ments. While most research efforts are directed towards developing improved fabrications techniques or more sensitive structures, we show that the performance of these sensors can be significantly enhanced by designing an appropriate interrogation strategy. In our scheme, a nanostructured plasmonic fiber probe is included in an optical fiber resonator and interrogated with a single-mode laser. A wavelength shift of the plasmonic resonance generates a mismatch of the resonator optical impedance, which is monitored and actively compensated by an optoelectronic gain element. We characterize the technique using samples with different refractive index and compare its performance to a conventional sensing scheme. Our cavity …