FIGURE 2.

Three major bioprinting techniques (A) extrusion-based printers use mechanical or pneumatic dispensing systems to extrude the bioink, (B) to force bioink droplets out of the nozzle, inkjet printers use either a pulsed heater to heat the print head producing air bubbles or a piezoelectric actuator to generate localized pressure via ultrasonic waves, and (C) laser-assisted bioprinters (LABs) use a laser beam on an absorbing substrate to generate heat waves that dispense the bioink onto a substrate. Reprinted with permission from (Ostrovidov et al., 2019) ^© 2019 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.