A few decades ago, every scientist shook samples by hand. But today’s scientists can choose from a wide range of shakers that use all kinds of motions. When shopping for the right shaker, there are many factors to consider; as the rock band Genesis would say, there’s an “ocean of motion.”
According to Jayne Bates, technical support manager at Cole-Parmer (Stone, United Kingdom), the most popular motion is orbital shaking followed by a rocking motion. “Orbital shaking is used for culture and growth of a number of microorganisms in a variety of different vessels,” she says. These shakers can stand alone or be part of an incubator, to keep the cells at the right temperature as they shake. Cole-Parmer makes a range of orbital shakers. A given application often works best with a specific shaker motion. For example, Bates says, “Rockers are used in molecular biology and biochemistry labs for washing gels and membranes and also for applications like binding assays and hybridizations.” Various manufacturers, including VWR (Radnor, PA), make rocking shakers.
Although customers who shop for shakers at Cole- Parmer tend to buy orbital and rocking shakers, scientists can select from other options.
One available motion resembles the by-hand shaking mentioned above. Scientists use these hand-motion shakers for various applications, including DNA extraction.
Instead of a “hand-shake approach,” wrist-action devices from Burrell Scientific (Pittsburgh, PA) swirl a sample. Daniel Snow, director of laboratory services at the University of Nebraska Water Sciences Laboratory in Lincoln, says that a wrist-action shaker is what he uses the most. When asked about the best applications for this shaker motion, he says that they include solvent extraction and equilibration.
Beyond hand shaking or swirling samples, you can slosh them with a reciprocating-motion shaker that goes back and forth. Troemner (Thorofare, NJ), for one, makes such shakers, which can be used in many different testing procedures. Some shakers combine orbital and reciprocating motions in one device, making them suitable for a variety of applications.
For delicate samples, some scientists prefer a rotating motion, which comes from devices made by Stuart (Stone, UK) and other vendors. These platforms let you pick the speed of rotation, and some even offer an angular adjustment.
Picking your motion
Given the wide range of shaker motions, how does a scientist know which kind to purchase? Bates gives us a few suggestions.
First, you “need to know how vigorous the mixing needs to be,” Bates says. “This will determine the type of motion.” For example, orbital, reciprocating, and wrist-action devices all can vigorously shake a sample.
Second, the type of holder for the sample must be considered. “For example, a tube roller, although giving a gentle rocking motion, is not suitable for containers with fragile gels inside, which are better placed on a rocking platform,” Bates explains. “Likewise, tubes need to be held in place while mixing or shaking to prevent them from moving around.”
So, with a little bit of planning, scientists can “swim through the ocean of motions” and find the right shaker for the tasks in their lab. The variety of platforms available ensures that one will probably be just right for any job and provide the control and repeatability that a particular experiment requires.
For additional resources on shakers, including useful articles and a list of manufacturers, visit www.labmanager.com/shakers