V&P Scientific invented Bubble Paddle Reservoirs in response to customers’ requests for a simple method to keep particulates in uniform suspension for both manual and robotic pipetting with minimum dead volume loss. We found that by designing Bubble Paddles with notches large enough between the Bubbles that would accommodate pipet tips we could keep the paddles spinning and creating up welling currents even while removing suspended particulates from the bottom of the reservoir. We also sculpted the bottom of the reservoirs to mimic the paddle shapes which enhances the turbulence efficacy and leaves space to accommodate the pipet tips.
In the photo above, the blue dye in the reservoir highlights the contours we have machined into the bottom of the stirrer. This design creates very powerful up welling fluid currents to keep very dense particulates like glass YSi SPA beads in uniform suspension. Another unique feature of the Bubble Paddle Reservoirs is their exclusive design that eliminates "fall out zones" where particulates fall out of solution that are so prevalent with other mixing reservoirs.
Here is what one of our customer’s at a major Pharmaceutical company had to say about our 384 Bubble Paddle Reservoir system "The reservoir is really the best thing that I have found for YSi SPA beads which immediately fall out of solution when not mixed" ..... The bubble paddle is essential for YSi beads."
Although the sculptured bottom design is essential for keeping very dense particulates in uniform suspension we have found that the shear forces that this design creates, especially at high speed can damage fragile cells or resins. We have solved this problem by creating a more open design in the reservoir bottoms. These open designs work very well in keeping lighter particulates uniformly suspended. See these products for examples of our open designs, VP 750-ECON-6, VP 750-ECON-6
A, VP 750AL, VP 750AL-1, VP 750AL-2, VP 751-D-1-SBS. The photo below illustrates 6 “U” channels instead of individual Bubble Paddle sculpting used in the VP 751-D-SBS.
We have 3 different methods for powering the spinning of our Bubble Paddles, the following describes and compares the applications and advantages of these different methods:
1. Direct magnetic coupling is a method where one of our VP 710 series Vertical Tumble Stirrer’s magnetic cylinder is used under or to the side of the reservoir to magnetically couple to the magnetic Stainless Steel Bubble Paddles and spin the paddles at a high rate of speed. Initially this method was used with all particulates except paramagnetic beads. Later we discovered if we used parylene encapsulated Bubble Paddles that the paramagnetic beads are suspended uniformly because they are only weakly attracted to the parylene encapsulated Stainless Steel Bubble Paddles and they are easily dislodged from the parylene encapsulated stainless steel at even low speeds. A recent modification of this method was the VP 754V-50 made to adapt to the Formulatrix Mantis dispensing system see this video https://youtu.be/kaL5wfZ700U to see how our Vertical Bubble Paddle system works in a 50 ml tube and is powered by a VP 710D2. The following video illustrates the Mantis at work dispensing paramagnetic beads from a VP 754V-50 reservoir to microplates – see https://youtu.be/7kE8AdssJA4
The direct magnetic coupling method is the most cost effective way for keeping all particulates in uniform suspension.
2. Dual magnetic clutch coupling through the reservoir’s wall to a motor’s drive shaft. The Magnetic clutch versions are used in applications where Z height or space is limited by a robotic platform’s configuration. This method can NOT be used with paramagnetic beads because the paramagnetic beads are attracted to strong NdFeB magnets used in the magnetic clutches.
3. Direct mechanical coupling of an aluminum (non-magnetic) Bubble Paddle to a motor’s drive shaft through a sealed bearing is another way to safely keep paramagnetic beads in suspension. It also has the advantage of being able to stir very viscous solutions or slurries that are too viscous for other magnetically coupled methods to stir.
We have helped many customers with many different uniform dispensing applications, please free to contact us with your particular needs. The chances are that we have already solved your application problem. For example a customer came to us with unique application to suspend cells in molten agarose. The VP 750-13-AL below was our solution. It is made from anodized aluminum and is used to keep the contents warm and suspended. This reservoir coupled with a heating block and a Vertical Tumble Stirrer was the solution. The aluminum's superior heat conductive properties are very useful in keeping molten agarose containing cells in a liquid state prior to dispensing to a another cooler media where the agarose will solidify around the cells.