Highly sensitive Fabry–Perot sensor for the detection of sodium copper chlorophyllin

Sodium copper chlorophyllin (SCC) is a widely used food coloring which is natural and stable, but excessive intake can lead to hepatotoxicity and neurotoxicity. In this paper, a highly sensitive Fabry–Perot sensing technique for the detection of SCC is proposed based on its photothermal properties. The suggested sensor is constructed of a single-mode optical fiber encapsulated in a fiber capillary forming a Fabry–Perot cavity. The experimental results showed that the sensitivity of the SCC sensor was significantly improved up to 9.128 nm/(mg/L) under 405 nm laser irradiation with a detection limit of 0.00219 (mg/kg), which is three orders of magnitude lower than that of conventional high-performance liquid chromatography (HPLC). The sensor has a compact form and an integrated all fiber structure, which has potential applications in food safety monitoring, drug manufacturing and illness diagnostics.