The two main strategies for liquid TEM. (a) The "nanoaquarium" approach in which the sample is sandwiched between two Si chips, each with an electron-transparent SiN window, and separated by a spacer. (b) A second approach that sandwiches the sample between two sheets of graphene and offers improved resolution. (a) adapted from de Jonge and Ross (2011) \cite{Jonge2011}; (b) reproduced from Yuk et al. (2012).\cite{Yuk2012}