Optical fiber SPR Pb2+sensor with tip-printed Fabry-Perot interferometer for temperature compensation.

Due to the serious biological toxicity and environmental refractory of heavy metal ions, the detection of heavy metal ions in liquids has attracted great attention. A novel fiber optic surface plasmon resonance (SPR) sensor is presented for detecting lead ions (Pb²⁺) with temperature compensation. The sensitivity of SPR channel to Pb²⁺ is up to -41.55 nm/μM and the detection limit is 7.05 nM after three parallel experiments by synthesizing Schiff base and fixing it on the sensor surface. Using femtosecond laser-induced two-photon polymerization (TPP) technology, a compact fiber-tip miniature Fabry-Perot interferometer (FPI) was printed at the end of the fiber-optic SPR sensor, thus realizing the temperature measurement in the process of detecting Pb²⁺. The FPI channel exhibits a linear response to temperature and remains unaffected by Pb²⁺ concentration, thus facilitating temperature correction. The experimental results also show that the proposed sensor has the advantages of compact structure, easy to prepare, good stability, specificity and repeatability. Therefore, this kind of sensor has great potential in various biochemical test applications, and opens up a new way to prepare compact and flexible optical sensors.