Figure 1
Illustration: Alan Stonebraker

Figure 1: A regular sensor (dipole element, upper left) and a cloaked sensor (dipole element surrounded by a plasmonic shell, lower left). The regular sensor shows maximum light scattering cross section (lower right, dashed curve) and maximum sensitivity (upper right, dashed curve) at the same frequency. The cloaked sensor exhibits similar sensitivity (upper right, solid curve), but drastically reduced scattering cross section (lower right, solid curve), thus rendering it practically invisible, without diminishing its sensing power. The shell is designed to compensate the scattering dipole of the inner sensor without changing the resonance frequency of the entire sensing structure. (Adapted from Al├╣ and Engheta [1].)