  We demonstrate imaging using scanning microwave microscopy (SMM) of vital
mitochondria in respiration buffer. The mitochondria are isolated from cultured
HeLa cells and tethered to a solid graphene support. The mitochondria are kept
vital (alive) using a respiration buffer, which provides nutrients to sustain
the Krebs cycle. We verify that the mitochondria are "alive" by measuring the
membrane potential using a voltage sensitive fluorescent dye (TMRE). The
organelles are measured capacitively at 7 GHz. Several technical advances are
demonstrated which enable this work: 1) The SMM operates in an
electrophysiologically relevant liquid (hence conducting) environment; 2) The
SMM operates in tapping mode, averaging the microwave reflection measurement
over many tapping periods; 3) A tuned reflectometer enables increased
sensitivity; 4) Variable frequencies up to 18 GHz are used; 5) In contrast with
traditional matching/resonant methods that exhibit high quality factor that
fail in the presence of liquids, interferometric/tuned reflectometer gives the
possibility to adjust the quality factor or sensitivity even in the presence of
the liquid.
