High speed photography of laser induced forward transfer (LIFT) of single and double-layered transfer layers for single cell transfer

Bioprinting technologies allow the construction of tissue-like structures from different cell populations. Fundamental research on the influence of the cell micro-environment requires printing of single cells in specific patterns on a microscopic scale. Single cell printing of living cells has been performed by nozzle based techniques or micro-pipetting, and laser-induced forward transfer (LIFT) has turned out to enable a virtually contact-free printing process. In this work the LIFT process from gelatine layers of 4% and 5% concentration is investigated using a high speed camera with 300,000 fps. We analyze differences in the jetting behavior caused by differently prepared transfer layers and the laser fluence. We assume that the velocity of a first, fast jet is a key parameter to control the viability of cells and precision of positioning. In comparison to a single gelatine layer a double-layer prepared from 5% gelatine coated with cell containing medium resulted in high cell survival rate and good precision