For the UFC30DV0S filter cup, it is possible to resuspend and recover particles that remain on the membrane after spinning. This can be achieved by flushing the last small volume remaining in the cup, or by adding some buffer back to the cup and using a pipette to flush it over the surface of the membrane to help recover particles. It is important to note that while some particles can be recovered, some loss is inevitable within the approximately 125 um depth of the membrane. There is no official protocol for this process, and recovery rates cannot be guaranteed as these devices are primarily tested for producing clean filtrate based on the pore size of the membrane, not for particle recovery from the cup.
However, it is not recommended to flip the filter cup upside down. Attempting to flip the cup upside down in another tube, adding buffer to what becomes the top of the cup, and spinning to collect the liquid that flows backward through the membrane is not advisable. This method can damage the cup and the vial and may cause a mess in the centrifuge. Although this practice has been tried, the product is not tested for such stress in that reversed orientation and doing so is strongly discouraged.