I'm injecting microsphere beads for particle counting using a syringe. To secure reproducible measurement results, the sedimentation should be minimized. Any good way to do this? Increasing density by adding some thick medium would help? In such case, what do you recommend?
If the medium is preferably not to be changed and the particles sediment only moderately, it can be helpful to mount the syringe vertically and stir the suspension continuously. Some syringe pumps can be mounted vertically or have a separate drive unit that can be mounted on a stand (e.g., https://www.kdscientific.com/legato-130-syringe-pump.html). Depending on the syringe size, the suspension in the syringe can be stirred with a magnetic stir bar or disc. For example, I use a 2 mm x 7 mm rod in a 3 ml syringe and a homemade magnetic stirrer consisting of a DC motor and two magnets on a holder. However, small magnetic stirrers are also available for purchase (http://vp-sci.com/products/stirrers-mixers/stirring-tubes-syringes-vials.html).
@ Muttuswamy Sivakumaran, microspheres are polystyrene particles, size ranging 3 to 6 um.
@ Laura Weirauch, your suggestion looks good. In my application, I need to inject sample to injection valve, so the syringe cannot be connected vertically. However, still using a stirrer looks good. Thanks!