1st Prize – Team 13: Zeiss MultiSEM Sample Mount
Sponsored by- Zeiss
Sponsor Advisors – Dr. Pascal Anger and Dr. Kyle Crosby
Team: Eric Bousfield, Stephen Ecsedy and Kyle Keeley
Faculty Advisor – Dr. Puxian Gao
Project summary – Carl Zeiss has built a multi beam scanning electron microscope (MultiSEM) to be used by a research team, led by Dr. Jeff Lichtman, at Harvard University. The team is using the 61 beam (MultiSEM) to image small sectional slices of a mouse brain, which are then layered upon each other to create a three dimensional map of neurons and their synapses. This process involves taking thousands of SEM images and subsequently processing them, therefore a major obstacle the team faces is the time required to image the brain slice samples. The advantage of the MultiSEM is that it uses 61 electron beams to image the sample, instead of just one beam which would be found in a conventional SEM, which allows for a much larger area to be captured in each image, greatly reducing the time required to build the three dimensional map of the mouse brain. The Harvard research team processes the samples by adhering them to 4 in diameter silicon wafers, which are then imaged using a visible light microscope (VLM), followed by the high-magnification high-resolution (4nm) image capture using the MultiSEM. The current system and mount used by the research team allow for relatively fast image capture;however the process flow and mounting system still need to be optimized.The goal of the senior design group is to design a new sample mount for the MultiSEM that can be used in both the VLM and the MultiSEM to increase the accuracy and the reproducibility of the images taken.
Initial work on the project consisted of materials research to determine the optimal material to be used for the sample mount. The current mounts use nickel plated aluminum, as aluminum is cheap and conductive but will produce a water absorbent oxide when exposed to atmospheric air, and a nickel coating will stop this oxide
growth. This material choice works well and is one of the most cost effective options. A new sample mount will be designed and prototyped using SolidWorks.This design will incorporate an adapter mount and permanent mount per wafer, both using a dovetail mounting system. This will allow for each wafer sample to have a designated mount, increasing the reproducibility of the images taken. Additional alternatives were investigated, including using pre-machined aluminum plates for use as the permanent wafer mounts.