BRAND Liquid Handling Station – Automated Wiping of Liquid Residues
The BRAND Liquid Handling Station (LHS) has a compact design and plug-and-play software to easily automate routine pipetting tasks, enhancing accuracy, precision, and reproducibility. A new feature of the LHS is its new automated tip wiping function, which ensures more reliable results. The ability to automatically wipe liquid residues from pipette tips is a significant advancement, particularly for difficult liquid types seen in common applications such as PCR, qPCR, and ELISAs
In routine laboratory work, pipette tips are often wiped on the destination or source vessel to ensure more accurate volume measurements and to minimize cross-contamination caused by liquid droplets. This practice is especially crucial for piston-operated pipettes, where wiping the tip on the vessel edge is even required for calibration according to DIN ISO 8655. With the latest software update, the LHS now includes an automated tip wiping function, enhancing both accuracy and reliability.
The LHS is designed to provide flexibility to a variety of small to medium throughput pipetting tasks. A benchtop automated liquid handler like the LHS can support a greater amount of simple pipetting work in the lab without the extensive cost of larger instrument while improving accuracy and precision.
In laboratory settings, viscous media often form droplets at the pipette tip during aspiration or dispensing. These droplets can negatively impact pipetting accuracy and, if not controlled, may lead to cross-contamination. The recent software update for the LHS addresses this issue with its new automated tip wiping functionality, which can be easily programmed into the system.
Automated Tip Wiping Process
The tip wiping process on the LHS begins by centering the pipette tip at a defined height within the vessel (Figure 1, left, start depth). The tip is then moved horizontally to the vessel’s edge, contacting the vessel wall, where it is lightly pressed (Figure 1, center, contact depth). A subsequent vertical movement raises the tip to a defined height (Figure 1, right, final depth), creating the wiping action.
The LHS software ensures that the pipette tip does not exit the vessel completely, preventing abrupt movements as the tip returns to its original position. Finally, the tip is moved horizontally back to the center of the vessel, completing the wiping process.
The tip wiping function can be enabled for various pipetting tasks, including aspiration, dispensing, pre-wetting, and mixing. The LHS software also tracks the number of wiping cycles performed, allowing users to monitor and assess the frequency of the wiping action.
Customization of Tip Wiping Parameters
The wiping function is typically enabled with just a few clicks in the LHS software. In certain cases, fine-tuning the wiping parameters can further improve performance. Key parameters that can be adjusted include:
- Start Depth and Final Depth: These parameters define the start and end points of the wiping movement, measured from the top of the vessel. The difference between these two depths determines the total length of the wiping motion.
- Contact Depth: This parameter controls how far the pipette tip presses against the vessel wall. While theoretically, a value of 0 mm would suffice, tolerances in vessel diameter and pipette tip straightness may require the tip to move slightly beyond the theoretical position to ensure effective contact with the vessel wall.
Additionally, the software offers two other customizable settings:
- Direction: This parameter allows users to select which side(s) of the vessel will be wiped. Multiple sides can be selected, causing the pipette tip to wipe the vessel several times.
- Wiping Timing: Users can specify whether wiping occurs before or after the air cushion is suctioned, or in both cases.
Benefits of the Automated Wiping Function
The new automated tip wiping function significantly reduces the risk of inaccurate pipetting due to liquid residues at the tip. By effectively wiping off any droplets, the LHS improves the accuracy and precision of pipetting, resulting in a lower variation coefficient of the pipetted volume. Furthermore, it minimizes the potential for cross-contamination, enhancing the reliability of experimental results.
With just a few simple clicks in the software, users can enable this wiping function, allowing for more consistent and accurate pipetting across a range of laboratory applications
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