In this brief review, an introduction of the underlying mechanisms for the shape memory effect (SME) and various shape memory phenomena in polymers is presented first. After that, a summary of typical applications in sensors based on either heating or wetting activated shape recovery using largely commercial engineering polymers, which are programmed by means of in-plane pre-deformation (load applied in the length/width direction) or out-of-plane pre-deformation (load applied in the thickness direction), is presented. As demonstrated by a number of examples, many low-cost engineering polymers are well suited to, for instance, anti-counterfeit and over-heating/wetting monitoring applications via visual sensation and/or tactual sensation, and many existing technologies and products (e.g., holography, 3D printing, nano-imprinting, electro-spinning, lenticular lens, Fresnel lens, QR/bar code, Moiré pattern, FRID, structural coloring, etc.) can be integrated with the shape memory feature.

We report an electrophoretic deposition method for the fabrication of gold nanoparticle (GNP) thin films as sensitive surface-enhanced Raman scattering (SERS) substrates. In this method, GNP sol, synthesized by a seed-mediated growth approach, and indium tin oxide (ITO) glass substrates were utilized as an electrophoretic solution and electrodes, respectively. From the scanning electron microscopy analysis, we found that the density of GNPs deposited on ITO glass substrates increases with prolonged electrophoresis time. The films possess high mechanical adhesion strength and exhibit strong localized surface plasmon resonance (LSPR) effect by showing high SERS sensitivity to detect 1 × 10⁻⁷ M rhodamine 6 G in methanol solution. Finally, the relationship between Raman signal amplification capability and GNP deposition density has been further investigated. The results of our experiment indicate that the high-density GNP film shows relatively higher signal amplification capability due to the strong LSPR effect in narrow gap regions between the neighboring particles on the film.