37 www.drivesncontrols.com October 2026 PRECISION MOTION n combine a can‑stack stepper motor with a threaded rotor and integrated leadscrew in a single, compact assembly. As electrical pulses drive the motor, the rotor advances in discrete steps, producing predictable linear motion without needing external gearing or complex mechanical conversion. For laboratories, this architectural simplicity can translate into improved repeatability and a reduced need for frequent recalibration. Stepper actuators can operate in open‑loop mode without relying on an encoder for precise positioning because 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. Proper sizing of stepper motors is important to avoid performance issues such as missed steps. Key considerations for pipetting must include ensuring adequate force margins, avoiding low‑frequency resonances and preventing sudden back‑driving events. Addressing these factors early helps to achieve consistent performance under high throughput conditions and to protect instrument reliability. The table highlights how different motor technologies can influence electronic pipette performance and system design. 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 its intended use. 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 type of motor is vital because laboratories rely on precise results. Labs have to to balance the need for repeatable, consistent output with reducing operator strain – making the choice of motor an increasingly important factor in electronic pipetting performance. n A comparison of the two main types of motor for electronic pipettes Parameter Brushed DC motor system Stepper linear actuator Motion Type Rotary → linear (requires gearbox + screw) Native linear motion Feedback Requires encoder/optical sensor Not required (open-loop) Positioning Accuracy High when closed-loop High due to discrete step control Mechanical Complexity Higher (multiple components) Low (integrated mechanism) Speed Higher Medium Cost Higher due to added components Most cost-effective Efficiency Higher due to coreless technology Lower based on stepper technology Noise & Vibration Low but dependent on mechanics Low; requires resonance avoidance Integration Effort Medium Low Suitability for Pipettes Ideal for ultra-smooth, closed-loop designs Excellent for compact, high-volume designs
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