In this Letter, we demonstrate a new, to the best of our knowledge, kind of photonic waveguide, in which the light propagates in the overlap of sub-wavelength patterned interdigitated combs. We present the fabrication and characterization of this waveguide, along with an adiabatic taper ensuring lossless transition with classical photonic waveguides. Finally, we explore some practical applications of this waveguide, as a bio-photonic sensor or as an optomechanical transduction scheme.