Anti-Capillary Tricks

Tricks for When Your Tweezers Eat Your Sample

When putting a sample onto a TEM grid, or when treating that sample with some sort of negative stain (or even just a water rinse), there is often the annoying problem that the tips of the tweezers wick away all (or some) of the liquid. This means that inconsistent amounts of sample or stain are put onto grids (and that the amounts can effectively change over time as the wicking occurs). Such issues can impact the consistency of the staining, which is a real headache given how inconsistent negatives stains can be in the first place! Here are a couple of suggestions to prevent (or at least minimize) this problem:

Buy anti-capillary tweezers

Most EM supply companies sell anti-capillary tweezers that are specifically designed to handle this issue. Instead of the two tips forming very close parallel surfaces where liquids can wick between them by capillary action, the anti-capillary style of tweezers keeps the tips further apart and lessens the capillary action effect. Anti-capillary tweezers generally work quite well but do tend to be more expensive than regular tweezers. The biggest problem with anti-capillary tweezers is that if either of the tips get at all bent, their precise alignment can be so distorted that not only do they no longer function as anti-capillary tweezers, but they also won't even clamp a TEM grid securely. If you are gentle with your tweezers, this is not a problem (and the only thing to consider is the additional cost).