I need to collect Raman measurements of Rotifer, Brachionus plicatilis, which are microscopic size (100 micro meter), however,  the motility of such organism is the biggest issues even with using POLY-L-L-YSINE (PLL) , since the adhesive is not strong enough resulting in  limited numbers of organism attached to the surface making the collection of the measurements is very difficult.

I need to freeze the movement of the organism and in same time keep it alive.  Researchers usually use  anesthetic or formalin especially in the case of  imaging techniques such as scanning electron microscopy (SEM), however, these chemicals may affect the spectra of the organisms

Are there other suggestions to overcome this problem?