Abstract
We present a miniaturized, disposable, normally-closed electromagnetic dispensing valve for the microliter range to process 96-well plates. The novel injection-molded valve is designed to fit into a 9 mm grid to realize an eight channel dispensing head, enabling the serial processing of well plates row-by-row. The presented dispensing valve design originates from a miniaturization study of a previously developed functional model. The outer diameter of the valve, including all actuating components, was reduced by 8 mm to an overall diameter of 8.5 mm without compromising the performance. Additionally, the actuation current of the valve could be reduced to 5 A. The valve is characterized for a volume range between 840 nL and 5.3 μL. The performance of the injection molded valve is competitive to commercially available dispensing valves, featuring the advantages of low fabrication costs, disposability, low mounting size, easy handling, and super silent actuation.
Highlights
The requirements on the dispensing performance of liquid handling systems in terms of precision, trueness and costs are increasingly growing
In a previous work [5], we developed a disposable, normally-closed, non-contact dispensing valve considering technical specifications provided by industry and researchers [6]
Normally-closed state, the plunger is in contact with the valve seat formed by the rear end of a nozzle due to the attracting force FRingMagnet between the plunger (permanent rod magnet made of Neodymium-Iron-Boron (NdFeB)) and the NC magnet
Summary
The requirements on the dispensing performance of liquid handling systems in terms of precision, trueness and costs are increasingly growing. The heat induced by the high actuating current in the previous functional model led to a degraded performance that had to be improved: The heat produced by the actuating current inside the coil is coupled into the liquid and typically reduces the viscosity of the liquid. This leads to changes in the flowrate, and, the precision of the dispensed volume over time is compromised. The actuating current had to be lowered by the miniaturized design from 10 A, previously, down to 5 A for the presented valve
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