A swarm of microrobots propels through the vitreous humor of the eye and reaches a small targeted spot on the retina.

Magnetic microparticles decorated with enzymes can penetrate mucin, which is a barrier for most particle-based drug carriers.

Plasmonic metasurfaces are a promising route for flat panel display applications due to their full color gamut and high spatial resolution. However, this plasmonic coloration cannot be readily tuned and requires expensive lithographic techniques. Here, we present scalable electrically driven color-changing metasurfaces constructed using a bottom-up solution process that controls the crucial plasmonic gaps and fills them with an active medium. Electrochromic nanoparticles are coated onto a metallic mirror, providing the smallest-area active plasmonic pixels to date. These nanopixels show strong scattering colors and are electrically tunable across >100-nm wavelength ranges. Their bistable behavior (with persistence times exceeding hundreds of seconds) and ultralow energy consumption (9 fJ per pixel) offer vivid, uniform, nonfading color that can be tuned at high refresh rates (>50 Hz) and optical contrast (>50%). These dynamics scale from the single nanoparticle level to multicentimeter scale films in subwavelength thickness devices, which are a hundredfold thinner than current displays.

Biosensors based on the localized surface plasmon resonance (LSPR) of individual metallic nanoparticles promise to deliver modular, low-cost sensing with high-detection thresholds. However, they continue to suffer from relatively low sensitivity and figures of merit (FOMs). Herein we introduce the idea of sensitivity enhancement of LSPR sensors through engineering of the material dispersion function. Employing dispersion and shape engineering of chiral nanoparticles leads to remarkable refractive index sensitivities (1,091 nm RIU−1 at λ=921 nm) and FOMs (>2,800 RIU−1). A key feature is that the polarization-dependent extinction of the nanoparticles is now characterized by rich spectral features, including bipolar peaks and nulls, suitable for tracking refractive index changes. This sensing modality offers strong optical contrast even in the presence of highly absorbing media, an important consideration for use in complex biological media with limited transmission. The technique is sensitive to surface-specific binding events which we demonstrate through biotin–avidin surface coupling.