Laser forward transfer is a direct-write technique used to print a variety of complex materials, from organic electric precursors to biological materials. In the laser forward process, a transparent substrate is coated with the ink material and a pulsed laser is focused into the ink to initiate the ejection of a small amount of material onto a receiving substrate. Motion of the ink and receiving substrates between successive laser shots allows printing of complex patterns.
Laser printing of stem cells is currently being investigated for tissue engineering applications. This image shows a laser transfer from a model system of 20 micron polystyrene beads in glycerol used to simulate the transfer of human stem cells. The ejected plume is less than 500 microns wide yet moves at tens of meters per second. To freeze the motion, the image is strobed with a 25 nanosecond pulsed plasma lamp, 10 microseconds after the laser hits the ink.