*3.2.5. Reservoir container*

The reservoir container is an important component of a liquid dispenser that is often ne‐ glected in troubleshooting. The material of the container can have a detrimental effect on the assay robustness, such as sticking of proteins to plastic surfaces. For peristaltic pump-based dispensers, we suggest using a jacketed glass flask connected to a water chiller (waterbath with adjustable temperature). Careful monitoring of the temperature in the flask using a thermometer is recommended, as the temperature set in the chiller is not always reflected in the container. Suspensions of cells, beads or nanoparticles have to be constantly stirred to prevent settling, which could result in uneven dispensing or clogging. The stirring speed needs to be optimized, as fast stirring can create bubbles and disturb biological components (cells). When working with large reagent volumes at the start of dispensing, the stirring may have to be reduced as the volume decreases to prevent foaming or bubble formation.

#### *3.2.6. Tubing extension*

Extensions can be implemented when the dispensing tubings cannot be immersed in the reservoir container because of its large dimensions. Some commercially available exten‐ sions allow for the 8 tubings of a standard cartridge to be coupled into single elongated tubing through metallic cannulas sticking out of a joint casing. For viscous solutions, these types of elongations can introduce bubbles due to the joint design, particularly during prime/empty cycles. The metallic cannulas can easily tear the tubing during fit‐ ting, which is ameliorated by using glycerol or alcohol to smoothen the surfaces. A bet‐ ter alternative is to build home-made extensions by attaching each of the new tubings to separate discarded tubings through connectors, which can be made by cutting the end of a pipette tip.
