On‐Chip Fluorescent Sensor for Chemical Vapor Detection

Abstract Organic thin‐film fluorescent sensor is an efficient tool for detecting trace chemical vapor, such as illegal drugs, explosives, nerve agents, and other dangerous substances due to its high sensitivity and quick response. However, most of the current device structures rely on space optics, which makes it challenging to integrate with complementary metal oxide semiconductor (CMOS) technology, and hence difficult for achieving chip‐level implementation. On the other hand, silicon nitride waveguide‐based photonics have recently shown strong potential for developing commercial‐scale fully integrated on‐chip gas sensors. In this work, to the best of the knowledge, the first chemical vapor detector based on fluorescence sensing is reported by the evanescent field of the waveguide on integrated photonic platform. By the simultaneous excitation and collection with the same waveguide, a detection limit of 0.19 and 93.7 ppb for methamphetamine and aniline, respectively, is achieved. Thanks to the good compatibility with CMOS fabrication processes, this on‐chip optical sensor can achieve production scalability as well as ease of integration with wearable electronic devices to meet the demands of portable, rapid detection. The technical route presented in this work provides a promising solution for compact, low‐cost fluorescence‐based gas sensors.