PNNL

Abstract

Focused Ion Beam (FIB) method is frequently used to prepare electron- and X-ray- beam transparent thin sections of samples, called lamellae. Typically, lamellae are prepared from only a sub-region of a sample. In this paper, we present a novel approach for FIB lamella preparation of microscopic samples wherein the entire cross section of the whole sample can be investigated. The samples used are microprecipitates of biologically precipitated calcium carbonate that are spherical, porous, and often hollow. Their geometry made the biogenic materials more fragile and challenging than materials commonly investigated using FIB lamellae. Our method enables the appropriate orientation of the lamellae required for further electron/X-ray analyses after attachment to the TEM grid post, and also facilitates more secure adhesion onto the grid post. This innovative approach allowed studying biomineralization at micro-scale, and it can provide novel insight into bacterial responses to microenvironmental conditions.