We found that while soaking the residues caused them to swell, they still adhered strongly to the propeller and the pH probe. Rotating the propeller while translating the probe head in the IPA bath was also ineffective. We discarded the idea of using mechanical brushes to scrub the propeller and the probe because the brushes would have to be cleaned or replaced, adding unnecessary processes. Brushes would also risk cross-contamination between runs. We achieved mechanical cleaning instead by using pressurised jets to dislodge residues. As shown in Figure , we fabricated a cleaning bath lid with a toroidal internal channel opening into a circular array of 1 mm cavities. When solvent is pumped into the channel with a diaphragm pump, the circular array directs pressurised jets of solvent onto the propeller and pH probe.