Integrated Optoelectronic Refractometer Based on ZnO Photodetector With EHD-Printed Electrodes and PDMS Waveguide

This letter reports the development of an integrated optoelectronic sensor for refractive index (RI) measurement, based on a zinc oxide metal–semiconductor–metal photodetector with electrohydrodynamic (EHD)-printed interdigitated electrodes and a polydimethylsiloxane (PDMS) waveguide placed on the sensor surface. The sensor detects variations in photocurrent caused by changes in the evanescent field of the PDMS waveguide when an analyte is deposited on it. A higher analyte RI results in decreased photocurrent. This work reports a promising application of conventional ultraviolet photodetectors for RI sensing. The use of scalable techniques, such as EHD printing and sputtering, together with direct integration of the PDMS waveguide, highlights the potential of the device as a compact and versatile sensing platform.