Enhanced photothermal signal detection by graphene oxide integrated long period fiber grating for on-site quantification of sodium copper chlorophyllin.

An enhanced photothermal signal detection method based on graphene oxide (GO) integrated long period fiber grating (LPFG) for on-site sodium copper chlorophyllin (SCC) quantification is proposed. SCC, as a porphyrin compound, can be photonically excited to induce a stronger photothermal effect. GO offers superior molecular adsorption and thermal conductivity properties; depositing it on the LPFG surface significantly improves the sensitivity and detection efficiency of the SCC photothermal signal, when irradiated with a 405 nm laser. The experimental results showed improved performance compared with those from uncoated LPFG, with a sensitivity of 0.0587 dB (mg L-1)-1 and a limit of detection (LOD) of 0.17 mg kg-1, which is also an order of magnitude lower than that of traditional high-performance liquid chromatography. The proposed method has potential applications in the fields of real-time food safety monitoring, environmental pollutant detection, and disease diagnosis.