Centrifuges, one of the true workhorse instruments of modern laboratories, were also one of the earliest scientific appliances. Core centrifuge applications (blood separation, sediment analysis, removal of particles from fluids, biological separations) remain vibrant, but new ones have emerged, particularly from molecular biology and biochemistry.
If one trend stands out in these markets, it is that sample sizes are shrinking: flasks have given way to eversmaller tubes, vials, and eventually microplates.
“We’re seeing many protocols transferred from tubes to microplates, and with that a demand for a means of centrifuging the plates,” observes Maurizio Merli, product manager for benchtop centrifuges at Thermo Fisher Scientific (Milan, Italy). “With these applications, customers are also demanding more speed (g-forces) and capacity.”
Microplates were not designed for traditional centrifuges, but most manufacturers offer centrifuges and rotors that handle these devices. Rotors use special swing-out buckets that process shallow-well microplates at low g-force and tall or deep wells at much higher speeds. Rotors used at high gforce have only two buckets and are designed to supply the highest possible g-force and the lowest possible friction and noise.
Jeff Antonucci, a product specialist at Hettich (Beverly, MA), mentions food as another strong market for centrifuges. Some of the more interesting applications he has recently worked on include measuring the fat content of milk, extracting honey from honeycombs, determining the waterholding capacity of fish muscle, and quantifying the percentage of pulp in orange juice. One restaurant recently approached him with the idea of using a benchtop centrifuge to extract essential oils from nuts and herbs. “Customers present us with all sorts of problems and special needs,” Mr. Antonucci says.
Although centrifuges are relatively simple devices, protocols often call for precise control of g-force, rotor acceleration to maximum force, duration, and temperature. Older instruments had three knobs (speed, time, temperature). Modern centrifuges feature advanced touch-screen controls that can dial up any parameter or stored method.
Plastics and composites are edging their way into benchtop systems for a number of reasons. As sample sizes get smaller, the masses required to move them around can shrink as well. Mr. Merli refers to a “universe” of materials in modern benchtop models, including carbon fibers and fiberreinforced plastics. These materials are lightweight but often as strong, durable, and chemically resistant as metals. They also absorb deformations better than metals and are significantly safer, due to their diminutive size and weight, in the event of a crash.
“More and more applications are jumping from floor to bench as a result of these improvements,” Mr. Merli tells Lab Manager Magazine. “We’re seeing performance now in benchtop units normally associated with floor models, including microprocessor control, energy efficient motors, and the use of composite materials.”
What customers want
Mr. Merli identifies two main groups of centrifuge purchasers: those who perform routine work and those who value flexibility. The first group includes technicians in environmental or blood processing labs who rely on a limited number of protocols; the second are more science-oriented. “They look for instruments capable of following the evolution of the laboratory,” Mr. Merli says. “These customers consider the centrifuge as more of an investment than a routine tool.”
Ease of use is something all customers ask for. According to Mr. Merli, ease of use can be delivered in many ways, but simplifying the interface is not necessarily one of them. The challenge to manufacturers is to present an interface that provides the average user with access to all critical features without having to refer to a user manual. His mission is accomplished, he says, when he sees a potential customer at a trade show who can access 95 percent of the centrifuge functions after exploring the instrument for five minutes.
Noise reduction has also been high on the wish list of centrifuge users. “When you have a machine right next to you constantly running at thousands of rpm, you want it to be as quiet as possible,” Mr. Antonucci says. Hettich has focused on making their benchtop models quieter by employing brushless motors (now industry-standard), better insulation, and a more effective air seal. These strategies, he adds, also make the centrifuge safer.
It would be difficult to imagine replacing a centrifuge with anything other than another centrifuge. Maurizio Merli recalls a quote he heard years ago: “Every morning, someone wakes up and figures out how to eliminate centrifugation from their process. Luckily, somebody else wakes up and finds a new use for centrifugation.”
For additional resources on centrifuges, including a purchasing guide and a list of manufacturers, visit www.labmanager.com/centrifuge.
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