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Microscopy Education


Destructive Tomography of Red Cabbage and Swiss Cheese: FIB-SEM Themed Educational Outreach


Konrad Rykaczewski , 1 * Abigail A. Howell , 2 and Maria Wieczynska 3 1 School for Engineering of Matter , Transport and Energy , Arizona State University ,


Tempe , 85287 2 LeRoy Eyring Center for Solid State Science , Arizona State University , Tempe , 85287 3 W.P. Carey School of Business , Arizona State University , Tempe , 85287


* konradr@asu.edu


Abstract: In this article we describe a simple, scalable, low-cost, and hands-on activity that introduces students to microscopy and “destructive tomography.” Specifi cally, we show that 2D images of sequential cross sections of several foods can be quickly reconstructed into a volumetric data set, shared, and interactively explored online using simple and fast image processing. We describe the entire process and present the results of destructive tomography of red cabbage and Swiss cheese as well as describe our experience with implementation of this activity in a local middle school.


Introduction


One of the traditional ways to excite young students about science and technology is to use a microscope to reveal to them features that are, for example, too small to see with a naked eye or hidden within a material. A common example of such outreach activity can include showing a group of students what an insect looks like up close when imaged with a scanning electron microscope (SEM). However, limited access to these tools and safety concerns oſt en restrict such outreach activities to a short demonstration by an experienced operator. In the last decade numerous routes for resolving these issues and expanding the role of microscopy in K–12 education have been proposed. Some high schools have received donations and acquired microscopes for their own campuses [ 1 – 5 ]. Alternatively, K–12 schools located in vicinity of higher education institutions can collaborate with universities to access their microscopy facilities [ 1 , 6 – 7 ]. Budget-constrained schools have taken advantage of technological advances such as remote online access and mobile table-top SEMs. For example, projects like Bugscope [ 8 ], Project ExCEL [ 9 ], and nanoMa- nipulator [ 10 ] allow K–12 students to remotely access SEM and scanning probe microscopes. Other eff orts


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bring portable light optical microscopes [ 11 – 12 ] and table-top SEMs [ 6 ] directly to the students. However, hands-on activities related to imaging, especially in 3D, which could be performed by a large number of students simultaneously, are rare.


In the last decade, the slice-and-view tomographic


method employing a focused ion beam (FIB) instrument combined with an scanning electron microscope (SEM) (a FIB-SEM) [ 13– 14 ] became a common way to characterize the 3D geometry and composition of a variety of materials from the nanoscale (nm) to the microscale (µm) [ 15 – 18 ]. In this article we describe a simple, scalable, low-cost, hands-on activity that introduces students to microscopy and tomography. Specifi cally, we describe how students can perform macroscale “destructive tomography” of diff erent morphologically rich food items. T e schematic in Figure 1 illustrates the experimental procedure consisting of sequential “slicing” away of a thin section


Figure 1 : Schematic of a typical “destructive tomography” procedure. After each slice an image is acquired and stored. Reconstruction software assembles the images into a 3D space that may be explored in various ways.


doi: 10.1017/S1551929517000839 www.microscopy-today.com • 2017 September


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