Brushed DC Motors Brushed DC motors translate direct current( DC) power into rotational motion without complex electronics. Their smooth operation and straightforward control make them attractive for handheld devices like pipettes. However, as pipetting requires linear movement, DC motors require additional components to convert the plane of movement. This system approach increases the considerations for instrument designers, requiring integration which must be competed under strict specifications.
As such, systems using DC motors typically incorporate feedback devices like magnetic encoders, to ensure accurate piston positioning and compensate for backlash or mechanical tolerances within the screw-driven assembly.
Stepper Actuators Stepper linear actuators offer a more integrated solution and are popular in electronic pipettes due to their direct linear motion and high positional resolution. A common example of this approach combines a can‐stack stepper motor with a threaded rotor and integrated lead screw in a single, compact assembly.
As electrical pulses drive the motor, the rotor advances in discrete steps, producing predictable linear motion without the need for external gearing or complex mechanical conversion. For laboratories, this architectural simplicity can translate into improved repeatability and reduced dependence on frequent recalibration.
Stepper actuators can operate in open‐loop mode without relying on an encoder for precise positioning as each step corresponds to a fixed increment of travel. This reduces system complexity and provides high resolution and predictable motion, ensuring consistent liquid handling across users and workloads.
Selecting the right motor technology is vital as laboratories rely on precise results no matter what industry or field of research they serve.
Proper sizing for stepper motors is important to avoid performance issues like missed steps. Key stepper actuator considerations for pipetting applications must include ensuring adequate force margin, avoiding low‐frequency resonances and the prevention of sudden back‐driving events. Addressing these factors early supports consistent performance under high throughput conditions and helps protect instrument reliability over time.
The following comparison highlights how different motor technologies can influence electronic pipette performance and system design.
Essential considerations
Both brushed DC motors and stepper linear actuators can be engineered to meet the precision demands of electronic pipettes, with the most appropriate choice ultimately depending on intended usage. DC motors deliver smooth motion but require additional components and closed‐loop control to achieve microliter accuracy. Superior speed and efficiency come with increased system complexity and cost.
The direct linear motion of stepper linear actuators enables strong repeatability and accuracy from simplified architecture. These qualities have made stepper actuators the preferred option for many pipette platforms.
Selecting the right motor technology is vital as laboratories rely on precise results no matter what industry or field of research they serve. Across disciplines, laboratories continue to balance the need for repeatable, consistent output with the equally critical priority of minimizing operator strain- making thoughtful motion system design an increasingly important factor in electronic pipetting performance.
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Issue 83 PECM 55