On March 25th and 26th, and on April 25th and 26th, Dr. Madeline Dukes, an application scientist from Protochips Company, introduced and demonstrated the liquid cell technique that Protochips has developed for transmission electron microscopy (TEM). The Poseidon system that enables liquid cell TEM has been available to NCSU and external researchers since June 25th.

For a long time, scientists have wanted to study soft matter in their original solution/solvent environment by high-resolution imaging techniques such as TEM. This has generally not been possible because of the high-vacuum environment of the TEM; any sample to be investigated in the electron microscopes has to be dried in a proper way. The liquid cell technique is a revolutionary testing system that allows liquid samples to be studied in TEMs without the traditionally required sample preparation. On the Poseidon test platform, a well-sealed specimen cell is designed to accommodate liquid samples via a pair of so-called “E-Chips”. Each E-Chip contains a small window with dimensions of either 500 x 20 μm, or 400 x 50 μm, with an amorphous SiN membrane 50 nm in thickness. The space between the two window membranes varies from 150 nm, 500 nm, to 5 μm, which allows soft matter with different sizes to be investigated. The liquid samples can be either dropped directly onto the bottom E-Chip and sealed by a top E-Chip, or driven into the well-sealed cell through tubing and pumps. The pumping system can also be utilized for dynamic in-situ studies inside the TEM. This system is very suitable for scientists to conduct the following experiments:

• Direct observations of cell cultures
• Direct observations of protein, bacteria, emulsion, gels, oils, creams, inks, paints, etc
• Chemical reactions under some limitations: two chemicals can be pumped into the well-sealed cell to make reaction occur
• Nanoparticles in solvent

Courtesy of Prof. Joseph Tracy and Wei-Chen (Ivy) Wu in the Department of Materials Science and Engineering, an example below shows TEM images of gold nanorods in water observed with the Poseidon system. The two images show gold nanorods before (left) and after (right) the energy filter was applied. The images were taken from JEOL 2010F Field-Emission Scanning Transmission Electron Microscope operated at 200 kV.

Gold nanorod in water observed via Liquid Cell Technique

For more details about applications of Poseidon, recently published papers, and application notes, please visit: http://www.protochips.com/products/poseidon.html