Seeing through Walls at the Nanoscale: Microwave Microscopy of Enclosed Objects and Processes in Liquids

Noninvasive in situ nanoscale imaging in liquid environments is a current imperative in the analysis of delicate biomedical objects and electrochemical processes at reactive liquid solid interfaces. Microwaves of a few gigahertz frequencies offer photons with energies of approximate to 10 mu eV, which can affect neither electronic states nor chemical bonds in condensed matter. Here, we describe an implementation of scanning near-field microwave microscopy for imaging in liquids using ultrathin molecular impermeable membranes separating scanning probes from samples enclosed in environmental cells. We imaged a model electroplating reaction as well as individual live cells. Through a side-by-side comparison of the microwave imaging with scanning electron microscopy, we demonstrate the advantage of microwaves for artifact-free imaging.