Robotic Liquid Dispensing Simplifies Lab Automation Processes

In clinical laboratories, the surge in testing demand – especially during events like the COVID-19 pandemic – has pushed manual workflows to their limits. Each year, more than 7 billion clinical lab tests are performed in the U.S., and routine diagnostics were even delayed during the pandemic as resources were diverted to COVID-19 testing. To handle such volumes efficiently and safely, laboratories are increasingly turning to automation for repetitive and time-consuming tasks, such as liquid sample dispensing.

MinebeaMitsumi is a global leader in precision components and one of the world’s largest manufacturers of stepping motors. With decades of experience in motors, bearings, and mechatronic solutions, MinebeaMitsumi has a unique perspective on laboratory automation. The content below, contributed by the MinebeaMitsumi team, explains how robotic liquid dispensing can simplify lab processes and highlights the critical role of stepping motors in achieving precise, reliable fluid handling.

The Case for Automating Liquid Dispensing

Laboratory technicians are in high demand, and lab managers are struggling to fill positions in today’s competitive job market. Coupled with higher volumes of patient samples, there is a growing need to further automate clinical laboratory systems.

Routine sample processing, such as DNA and RNA extraction, accounts for the majority of testing carried out by lab technicians. This process involves treating a blood sample with various reagents to isolate a patient’s DNA so that further testing, such as PCR analysis, can be performed. In order to transfer small volumes of liquid – even smaller than a microliter – a technician typically uses a pipette. Pipettes are capable of measuring and dispensing precise amounts of liquid. As a manual process, this can be quite repetitive, time-consuming, and potentially increase the probability of human errors leading to further delays in sample processing.

Automated solutions are being developed to replace manual liquid dispensing with improved throughput and accuracy. From single electronic pipettes that include a battery-powered motor to full-scale robotics solutions for high-volume sample processing, automated liquid handling can benefit laboratories of all sizes.

Stepping Motors Deliver Optimal Precision

How are automated liquid handling systems able to extract and dispense such precise amounts of liquid? The answer lies in the use of stepping motors as key actuators for pipettes and dispensing mechanisms. Stepping motors move in discrete steps, each corresponding to a fixed rotation angle, which makes it straightforward to translate motor steps into specific liquid volumes. For example, a standard hybrid stepping motor typically has 200 steps per revolution (1.8° per step). If each step is defined to move one microliter (μL) of liquid, then one full rotation of the motor dispenses 200 μL in 1 μL increments. Using a stepper motor with finer resolution – say 400 steps per revolution (0.9° per step) – would allow volume increments of about 0.5 μL for the same 200 μL total range. This level of control simply isn’t feasible with manual handling.

Stepping motors also provide high holding torque, which means once the motor has drawn a volume of liquid into the pipette, it can hold that position (keeping the liquid in place) until it’s instructed to dispense. The motor will not slip, ensuring the volume stays accurate. Additionally, because stepper motors move in known increments, the system can obtain positional feedback (how much liquid has been dispensed) just by counting the input pulses – no separate sensor or encoder is required for basic feedback. This inherent precision and self-monitoring capability make stepper motors easy to control via simple pulse commands.

Hybrid and PM stepping motors are best suited for highly repeatable tasks that require precise motion control, such as liquid handling and lab automation.

Originally published at Robotic Liquid Dispensing Simplifies Lab Automation Processes

Conclusion 

Robotic liquid dispensing, powered by precision components like stepping motors, is transforming how laboratories handle large sample workloads. By automating pipetting and other fluid-handling tasks, labs can process more tests in less time, improve consistency, and protect staff from repetitive strain and hazardous exposures. MinebeaMitsumi’s expertise in miniaturized motors and mechatronics provides a foundation for these innovations, ensuring that even complex motions (like sub-microliter liquid measurements) can be executed reliably. In summary, leveraging stepping motor technology in lab automation leads to higher throughput and improved accuracy, helping healthcare providers deliver timely and reliable test results.

MinebeaMitsumi also offers an innovative closed-loop stepping servo system for collaborative robot grippers, which showcases the versatility of stepping motor technology in robotics. The lightweight electric gripper (pictured above) uses a patent-pending spiral cam drive, powered by a hybrid stepping motor and supported by high-precision NMB ball bearings for efficiency and reliability. Paired with an ST-Box controller, this gripper system can precisely control gripping force and speed, detect when it has picked up an object, and even adjust its open/close limits to match the size of the object – reducing cycle time between picks. Users can program up to 16 different gripping modes and integrate the unit easily with PLCs or cobots via standard I/O or RS-485 communication. This is a great example of how stepper motor solutions can be applied beyond the lab, in broader automation contexts like manufacturing and robotics.

At Pacific International Bearing Sales, we are proud to collaborate with leading manufacturers like MinebeaMitsumi to bring these advanced motion solutions to our clients. If your organization is looking to implement robotic liquid handling systems, precision electric grippers, or other automation solutions, our team is here to help. Contact us today [email protected]  to discuss your needs, request technical details, or get guidance on selecting the right components for your application. 

FAQ

Q: Why should we automate liquid dispensing in clinical labs?
A: Automating liquid dispensing helps labs handle high sample volumes more efficiently and consistently. With billions of tests conducted annually, manual pipetting can become a bottleneck. Robots and automated pipettes can work around the clock, significantly increasing throughput. Automation also reduces human error – a machine will dispense the same tiny volume every time, whereas humans may make mistakes or experience fatigue during repetitive tasks. By freeing technicians from monotonous pipetting work, it allows them to focus on more complex analyses and improves overall lab productivity. In short, automated liquid handling ensures faster processing, fewer errors, and better use of skilled lab personnel.

Q: How do stepping motors improve precision in liquid handling systems?
A: Stepping motors are key to the precision of automated liquid handlers. These motors move in fixed increments (steps), which means the motion (and the dispensed volume) can be finely controlled. For example, each step might correspond to a very small volume (like 1 microliter), so the system knows exactly how much liquid is moved with each pulse to the motor. Steppers also have the benefit of holding torque – once they move to a position (say, drawing up 50 μL of liquid), they hold that position without drifting, keeping the liquid in the pipette until it’s time to dispense. Importantly, stepper motors don’t require separate feedback sensors for position in many cases, because the controller can track the step count to know the plunger position. This inherent accuracy and reliability make stepping motors ideal for tasks like pipetting, where precise, repeatable motion is crucial.

Q: What is the difference between hybrid stepping motors and PM stepping motors?
A: Permanent Magnet (PM) stepper motors and Hybrid stepper motors are two common types. PM steppers (sometimes called “tin can” steppers) are simpler in construction and usually less expensive. They have a permanent magnet rotor and tend to have larger step angles (e.g. 7.5° or 15° per step), which means less fine positioning by default. Hybrid steppers, as the name implies, combine design elements of PM and variable reluctance motors – they use toothed rotors and often a stronger magnetic circuit. Hybrids achieve much smaller step angles (typically 1.8° or even 0.9° per step) and deliver higher torque and better speed performance, albeit at a higher cost and complexity. In short, PM steppers are cheaper and good for basic applications, while hybrid steppers offer higher torque and finer resolution. For example, a hybrid motor can run faster and with more torque than a similar-sized PM motor, which is why hybrids are common in demanding applications. Choosing between them depends on the requirements: if you need high precision and torque, a hybrid stepper is usually the better choice, whereas for simple, cost-sensitive uses a PM stepper might suffice.

Q: What is a “closed-loop” stepping servo system?
A: A closed-loop stepping servo system refers to a stepper motor-based system that incorporates feedback control, similar to a servo motor. In a normal (open-loop) stepper setup, the motor moves in response to commands but does not verify its position. In a closed-loop system, the stepper motor is equipped with an encoder or sensor that continuously monitors its position and sends feedback to the controller. This way, the system can correct any missed steps or position errors on the fly, combining the best of both worlds: the precision and simplicity of a stepper motor, and the reliability of a servo system with feedback. The result is that the motor will not lose steps under load (because any deviation is corrected), and it can adjust torque and speed as needed to meet the target motion profile. MinebeaMitsumi’s ST-Box technology, for example, turns their stepper-driven gripper into a closed-loop system – ensuring the gripper fingers move exactly as commanded, with no missed positions. For users, a closed-loop stepper system is easier to set up than a traditional servo drive but provides comparable assurance of accuracy and fault correction.

Q: How can we get started with implementing automated dispensing or motion solutions in our lab?
A: Implementing automation starts with identifying the tasks that will benefit most – such as liquid dispensing, sample handling, or repetitive assembly – and then choosing equipment that fits your throughput and precision needs. PIB can assist you in this process. We offer consulting to determine the right solution and supply the necessary components, from stepping motors and drivers to complete dispensing rigs or robotic grippers. For example, if you need to automate liquid handling, we can help you select an appropriate electronic pipetting system or design a custom setup using stepper motors and controllers. For gripping or pick-and-place tasks, we can provide advanced solutions like MinebeaMitsumi’s closed-loop stepper servo gripper or other robotic end-effectors. Our team will ensure the components are properly integrated and tuned for your application. To get started, feel free to reach out to us – we’ll work with you to develop a tailored automation plan that improves efficiency and results in your specific environment.