Contents: (Small 18/2012)

SERSPNA substrates created by B. T. Cunningham and co-workers on page 2878 provide a dense array of electromagnetic hot spots within ~10 nm gaps between adjacent gold domes.The structures are inexpensively produced over large surface areas on fl exible plastic substrates using nanoreplica molding to produce an array of polymer cylinders.The nanogap spacing is controlled via the thickness of deposited fi lms of silicon dioxide and metal, so the structure can be produced without lithography.These PNA substrates are suitable for the real-time detection of biological and chemical compounds. Flexible ElectronicsA stretchable, microscale inorganic light-emitting diode (µ-ILED) with an integrated coil for wireless power delivery is described F. G. Omenetto, J. A. Rogers, and co-workers on page 2812.The ultrathin layout of the µ-ILED, the serpentine structures in the metal traces, and the rubber substrate combine to provide a system that can be deformed to large levels of strain.Detailed studies of the mechanics reveal the underlying design principles.The physical characteristics and constituent materials enable its use as an implantable light source, as illustrated through in vivo studies using animal models.