One can prepare the SPR-based optical fiber sensor using
polymer materials by doping precious metals nano-particles [79].
Fig. 4(a) shows the schematic illustration of fabricating the polymer
nanofibers by direct drawing of PSS-GNRs PAM solution (Inset
is the PSS-GNRs/PAM solution, PSS-GNRs stands for Poly(sodium
4-styrenesulfonate)-gold-nano-rods). The GNRs were synthesized
by the seed-medicated method (See the detailed process in the
supporting information of Ref. [79]). After being coated with PSS
and sufficiently stirring, the 1 mL PSS-GNRs solutions was dissolved
in 38 mg PAM without aggregation. The tungsten probe
was used then to dip up a bead of solution and stretch the polymer
amorphous nanofiber from the GNRs doped PAM solution. Fig. 4(b
and c) illustrates the optical micrograph of a PAM nanofiber doped
with GNRs, where the localized surface plasmon resonance (LSPR)
of the single GNR in the PAM nanofiber had been observed. By doping
the single GNR in the PAM nano-fiber longitudinally, Tong et al.
transformed the photon energy into SPR vibration energy with a
conversion ratio of more than 70%, and implemented a humidity
sensor with the response time of 110 ms and the lowest power
of 500 pW [80,81].