Sample Stage for Fast, Continuous Tomography in In Situ Transmission Electron Microscopy

Current tomography holders do not allow dynamic experiments. Furthermore, the slow nature of data acquisition limits their use to materials that are robust under the electron beam. With the advancement of direct electron detectors, several functional materials that are electron beam sensitive such as perovskites, metal organic frameworks and lithium ion battery materials can now be studied in 3D by electron tomography. However, the current methods use the microscope’s goniometer to tilt the sample, which limits the speed of data acquisition and also has a limit in its tilt range, resulting in artifacts in the reconstruction due to the presence of a “missing wedge”.Proposal of Solution: In our preliminary work, we have developed a prototype that uses a DC motor with a fine gearhead that rotates the sample as opposed to the conventional approach in which the rod is rotated by the goniometer. In this proposal, we propose to extend our aforementioned preliminary efforts in electron tomography by achieving the following:Improved tomography holder with higher concentricity: Using advanced manufacturing techniques, we will build a holder that provides better concentricity and provide sample rotation using a built-in piezo motor. Add in situ capabilities. This will allow use of chips or MEMS devices that are typically used for in situ TEM experiments. To take advantage of the 360 degree rotation we will also prototype a continuous rotation tomography holder with a built-in heater that will heat a sample installed on a tungsten needle. Develop a control system: A feedback control system will be developed connecting the holder, detector and the microscope’s stage using Python that will allow users to perform in situ tomography experiments from a single program.Plan: For the first phase of the project, we would i) develop and prototype two versions of in situ continuous rotation tomography holders: a) holder compatible with currently available MEMS devices and b) holder with a heating attachment and tungsten needle. ii) develop a feedback control system that keeps the sample at eucentric height and in the field of view at all tilt angles with minimum radiation damage. iii) demonstrate a heating experiment using the prototype at NCEM, Berkeley Lab.Commercial Applications: Electron tomography holder with in situ capabilities can be used to understand failure mechanisms in various materials of interest in energy harvesting and storage applications.