MRI: Acquisition of a Scanning Electron Microscope with In Situ Capabilities

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

Non-Technical Abstract Photography records a moment in time, but movies capture the transformations that occur from one moment to the next. Consider a chick hatching from an egg and how much more informative a movie is as compared to one photograph of the egg and another of the chick. In the study of materials, we are interested in how solids respond to various environments and stimuli. In the past we have studied transitions in materials by making many duplicate samples and stopping the transformation at a few time points to take essentially still photographs and then attempting to connect the dots between these time points. This approach is tedious and slow, not to mention riddled with uncertainties about missed information. The new instrument enables researchers to stimulate materials and record their response at the same time. Our imaging method detects chemical and topological features 500 times smaller than the thickness of a human hair, and also allows for sample manipulation on this length scale. Stimuli that are important for designing extraordinary properties into a new material include exposure to liquids and gases, temperature control, electric fields, and mechanical deformation. The materials to be studied have a wide variety of applications including membranes for fuel cells, highly sensitive chemical sensors, flexible electronics, engineered coatings, structured surfaces for tissue engineering, and high-efficiency solar cells. The instrument will be incorporated into our highly successful, professionally staffed regional facility that is open to all academic, industrial, and governmental scientists and engineers. Technical Abstract The new scanning electron microscope is equipped with a uniquely broad array of accessories to enable the combination of high-resolution imaging and nanoscale manipulation for powerful in situ experiments involving controlled stimuli and correlated response. In situ capabilities include nanoscale manipulation of specimens and exposure to fluids, gases, electrical fields, light, mechanical deformation, and temperature. The in situ approach enabled by this instrument is not only cleaner and more efficient than "in-and-out" procedures involving multiple instruments and exposure to air, it also makes possible entirely new, albeit high risk, initiatives to understand fundamental processes at the nanoscale. The experiments to be conducted go far beyond structural imaging, while incorporating this basic feature as an essential ingredient. We will also acquire an optical microscope with digital imaging/recording; this will serve as a "front end" for sample screening and preliminary measurements to inform and ensure the optimum use of the SEM. Seventeen faculty members associated with seven departments and representing all ranks have envisioned and planned remarkable experiments for this new instrument within four topical areas of nanoscale science: electrically responsive materials (including fuel cell membranes, flexible electronics, and nano circuitry), phase transitions (including superlattices, phase separation, and patterning), surface phenomena (including wetting, cell response, gas adsorption, and self-assembly), and mechanically responsive materials (including hard materials, proteins, and fluids). The user base will provide a focal point for initiating new collaborations, interactions and training/education initiatives. The instrument will be incorporated into our highly successful, professionally staffed regional facility that is open to academic, industrial, and governmental scientists and engineers. To encourage the full participation of local liberal arts colleges, particularly the highly selective women's college Bryn Mawr College, we will provide technical assistance and machine use to researchers from these institutions.