Cell settling effects on a thermal inkjet bioprinter

This paper seeks to quantify cell settling in the print media reservoir of a bioprinter in order to determine its effect on consistent cell delivery per printed drop. The bioprinter studied here is based on the thermal inkjet HP26A cartridge, but any system that dispenses controlled volumes of fluid may be affected similarly. A simple model based on Stokes' law suggests that the cell concentration in the bottom of the reservoir should increase linearly up to some maximum and that the cell concentration in the printed drops should follow this trend. The results show that cell output initially followed the predicted increasing trend, but then peaked and decreased. The timing and rate of the decrease related to the number of use cycles for the cartridges. The results provide guidance for modifications to the printing process to ensure consistent printing of cells.