Ava1000 100gm

We employed two imaging techniques to observe the movement of cells in ambient air and sinking in a liquid-filled bath. First, the evolution of jet morphology was observed using a CCD camera (avA1000-100gm, Basler AG Inc., Ahrensburg, Germany), zoom lens, and nano-pulsed light (150 ns, NP-1A, Sugawara Laboratories Inc., Kawasaki, Japan) based on stroboscopic flash photography to design the proper characteristics of cell-laden drops, such as the velocity and number of satellite drops. Each stroboscopic image was recorded at 10 frames per second by synchronizing this equipment using a NI DAQ boards (NI USB6351, National Instruments Corp., Austin, Texas, USA), and the velocity of the leading drop was evaluated. Next, cell behaviors were observed at 12,000 frames per second using a high-speed camera (Fastcam SA3 120 K M3, Photron Inc., San Diego, California, USA), zoom lens, and halogen light (LS-F150HS Light Bank, Seokwang Optical Co., Ltd, Hwaseong, Korea) to analyze the dynamics of cell impact and sinking. The cell-laden drop impacted onto the surface of the transparent acrylic bath filled with a water-miscible fluid, such as ethanol. After the drop impacted the DMEM-filled bath, sinking cells were tracked and the sinking displacement was measured. The measurement was repeated 10 times.

A home-built inkjet apparatus was employed for this experiment. The system comprised a piezoelectric inkjet nozzle with a diameter of 40 μm (MJ-ATP-01-040 DLC, MicroFab Technologies), a waveform driver (JetDrive, MicroFab Technologies), a nano-pulsed flashlight source (NP-1A, SUGAWARA Laboratories Inc), a CCD camera (avA1000-100gm, Basler) with a high magnification zoom lens (Zoom 6000 Lens System, Navitar), and the 5 × objective lenses (Infinity Corrected Long Working Distance Objective, Mitutoyo). The inkjet nozzle belongs to a squeeze-mode design where a piezo transducer wrapped the outside of a glass capillary tube. The inkjet nozzle pushes out the liquid when receiving the trigger pulse at a jetting frequency of 10 Hz. Based on single-flash high-speed imaging, all jetting images were obtained by the ultra-short pulse flashlight and the CCD camera. The drop watcher system employs a stroboscopic principle to capture the jetting image. The strobe trigger delay time can be adjusted in 1 μs increments. The very short flashlight with a duration of 180 ns avoided significant motion blurring. These components were electrically synchronized and controlled by an embedded controller (cRIO-9035 and NI-9401, National Instruments).