As we make our way in the world each day, we come in contact with many objects and things that give us no cause for concern. We use things without giving a lot of thought to how they came to market, and how safe they might be. It’s easy to do this, to relax as you live your life, because a combination of science and technology has been used for testing and quality control. Our lives depend on all of the hard work that goes into initial and ongoing product testing, and the resultant design changes that keep us safe.
One of the advanced testing methods is scanning electron microscopy, or SEM, which can produce high-resolution images of the surfaces being studied. While light microscopy relies on visible light, the SEM can provide magnification that is much greater, up to 100,000X. In addition, the depth of field can also be 100 times greater. Basically, the SEM produces a beam of electrons in the chamber where the sample is held. The electrons in the beam then encounter the atoms in the sample and produce signals that can be analyzed.
Testing Edible Probiotic Delivery System
Many existing probiotic delivery methods are based on dairy, but during production the probiotics may lose viability because of heat, mechanical stress and the like. Researchers were hoping to develop a new way of providing consumers with healthy probiotics in baked goods that would be available in stores.
To do this, they created an edible probiotic film that could be used to coat the baked product. They then used the SEM to see whether the heat of baking destroyed the probiotics. It was found that the edible film didn’t adversely affect the crust on the baked items, and when whey proteins were added the level of probiotic presence was maintained.
Studying Concrete Cracks and Safety
Another interesting use of SEM testing comes in the form of studying microcracks in concrete that appear both in the original concrete forms and when the concrete is subject to load-induced stress. The new procedure involved putting a metal ally that was molten into cracks that had been caused by pressure from the loads.
The SEM was then used to scan, measure and record images from cross sections of the concrete. SEMs were initially used with concrete to study hydration formulas when concrete was first developed and refined.
Tracing the Source of an Environmental Problem
The oft-photographed Golden Gate Bridge, which connects Marin County and San Francisco, was built during the 1930s. At that time its iconic color was created by painting it with a primer of red lead paint, and then coating it with a top coat that also contained lead. Later, in a 30-year project, the lead paint was removed and replaced with zinc-based coatings.
Unfortunately, soil under the bridge exhibited a high content of lead. This could have come from leaded gasoline, the lead paint or some other cause. Testing and the use of an SEM along with an EDS (energy dispersive x-ray spectrometer) showed that specks found in the soil below the bridge were from the paint, and were the cause of the significant levels of lead.
If you are involved with product safety and quality control, you can use an SEM to test samples at a microscopic level. Many different industries can benefit from these testing capabilities, and the SEM can also help identify key elements causing environmental problems.
