MIT Shows Off High-Speed Photography Of A Waterjet Hitting A Water Drop

Researchers at MIT have been conducting an experiment that, on the surface, may not sound particularly useful. The experiment has researchers shooting a high-pressure stream of water through a water droplet. The team says that if the process is precisely and thoroughly understood, the experiment could help scientists learn how to inject fluids, like vaccines, into the skin without using needles.

For the experiment, engineers at MIT worked with researchers from the University of Twente in the Netherlands. The experiment had researchers shooting small jets of water through different kinds of water droplets. The jets of water were fired hundreds of times, and the process was captured using high-speed cameras.

Researchers discovered similar impact dynamics as seen in famous photographs of a bullet hitting an apple taken by Harold Edgerton at MIT. The dynamics of the bullet impacting the apple inside the apple weren't seen in those famous photographs. However, since the water droplet is clear, the researchers could see the entire process of impact. The experiments allow the team to develop a model predicting how a fluid jet impacts drops of a known viscosity and elasticity.

Researchers note human skin is a viscoelastic material, and their newly developed model could be tuned to predict how fluids could be delivered through the skin without using needles. The main goal of the experiment is to explore needle-free injection. One major benefit of injecting fluid into the body without using needles is that it eliminates needle sticks to the patient making people more likely to take their injections. Eliminating needles also makes the process safer for those administering the injections as there is no risk of a needlestick.

MIT researcher David Fernandez Rivas says the experiments allow the team to learn how they can create jets of the right viscosity and shape to inject the skin. The design Rivas and his team have come up with uses a low-power laser to heat a fluid-filled microfluidic chip. Heating the chip creates a bubble in the fluid that pushes the liquid through the chip and the nozzle at high speed.