AC/DC millivoltage sensor by means of ITO-coated optical fibers: towards monitoring of biosignals

This contribution shows the monitoring of AC and DC millivoltage signals by means of lossy mode resonances generated by Indium Tin Oxide (ITO) on optical fibers. Sensors were obtained by sputtering ITO thin-films onto 25 mm-length segments of 200 μm bare optical fibers. Depositing a 1 μm thin-film of ITO leads to obtain reduced thin-film resistances of near 340 ohms. This allows the detection of voltage signals by monitoring the wavelength shift of the resonances. Sensitivities up to 40 nm/V can be achieved when tracking sinusoidal signals of a few cents of mV peak-to-peak. This opens the path for further research pursuing the detection of biomedical signals.This work has been supported by the Spanish National Research Agency through the project with reference TEC2016-78047-R, by the OPTISENS Government of Navarra Research Project and by a predoctoral research grant of the Public University of Navarra