We are developing a micro/nanofluidic device to study liquid phase processes in situ TEM. The new nanochannel liquid cell chip design alleviates the persistent issue of membrane bulging in clamped chip systems and offers the possibility of achieving high level flow control and mixing in the imaging region. The earlier version of the device were used to quantitively measure the mean inner potential (MIP) of liquid water [1] and the electron inelastic mean free path (IMFP) in liquid water [2].

The chips are made from two separately treated wafers that are bonded together and typically embody an array of nanochannels, each typically about 2 µm wide and 50-500 nm deep, see figure 1 (a, b)[3]. Because the liquid containing channels of the chips have width down to 2 µm, the resulting bulging from the internal ambient pressure difference to the TEM vacuum is less than 10 nm, and the liquid layer thickness is well defined by the microfabrication process [2]. The nanochannel fluidic system has four inlets/outlets and thus offers the possibility of running experiments with numerous different gasses and liquids to observe reaction between them. The channel system can be lithographically designed to bring together flows of reagents in one place, or to affect how particles and molecules may be trapped, filtered and otherwise manipulated inside the channel system.