| AVS 60th International Symposium and Exhibition | |
| Helium Ion Microscopy Focus Topic | Thursday Sessions |
| Session HI-ThA |
| Session: | Imaging and Lithography with Helium Ions |
| Presenter: | S.A. Boden, University of Southampton, UK |
| Authors: | S.A. Boden, University of Southampton, UK G. Mills, Morriston Hospital, UK P.A. Evans, Morriston Hospital, UK M. Bagnall, University of Southampton, UK H.N. Rutt, University of Southampton, UK |
| Correspondent: | Click to Email |
In addition to a smaller probe size and so higher resolution imaging, a key advantage of the helium ion microscope (HIM) is the large depth-of-field (DOF) it provides, typically five times larger than that of a scanning electron microscope [1] . Here we exploit the high resolution and large DOF of the HIM in a study of how diluting blood affects the resulting blood clot microstructure.
Blood clot formation involves the polymerization of fibrinogen into fibrin, forming a fibrous mesh which binds the clot together. Clinicians are looking for better ways of determining what effect dilution has on clot formation to improve the management of fluid replacement therapy. One such method being developed is a rheological technique that measures the gel point (GP) of clotting blood and the incipient clot microstructure complexity at the gel point (the fractal dimension, Df) [2] . In this study, HIM is used to characterize fully matured clots to demonstrate that variations in the haemorheological properties measured during clotting (Df), as a result of diluting with isotonic saline, can be correlated with changes in the resulting microstructure of the mature clots. Demonstrating the link between Df of the incipient clot and the resulting clot microstructure is an important step in developing Df as a biomarker for use in management of fluid replacement therapy and potentially as a point of care test.
HIM is used to image blood clots formed from samples diluted by isotonic saline to various degrees (0 – 60% dilution), so that the average fibril width can be measured and compared to the Df of the sample. The large DOF of the HIM (due to its small beam convergence angle) is particularly useful when imaging blood clot microstructure because of their inherent 3D nature and high degree of surface topography. A large number of fibrils appear in focus within one image and so a large number of width measurements can be extracted. Furthermore, the large DOF allows the capture of high quality stereopairs from which the 3D structure of the fibrin network can be analyzed. In addition, the HIM enables imaging of the uncoated fibril surface at a higher resolution compared to SEM which could lead to a deeper understanding of the effects of dilution on blood clot fibril structure.
[1] B. W. Ward, J. A. Notte, and N. P. Economou, Journal of Vacuum Science and Technology B, vol. 24, no. 6, pp. 2871–2874, 2006.
[2] P. A. Evans, K. Hawkins, R. H. K. Morris, N. Thirumalai, R. Munro, L. Wakeman, M. J. Lawrence, and P. R. Williams, Blood, vol. 116, no. 17, pp. 3341–6, Oct. 2010.