Researchers from ETH Zurich have created an ultrasonically actuated glass needle that can be attached to a robotic arm, thereby enabling microscopic robots to pump and mix microscopic amounts of liquids and to trap particles.

To accomplish this, the ETH Zurich team combined conventional robotics and microfluidics, resulting in a device that uses ultrasound and that can be attached to a robotic arm.

Source: ETH ZurichSource: ETH Zurich

The device, which features a thin, pointed glass needle and a piezoelectric transducer that causes the needle to oscillate, is reportedly appropriate for tasks in micro-robotic and micro-fluidic applications and can also be used to automate those applications.

According to the researchers, they can alter the oscillation frequency of the needle by dipping the needle into a liquid, thereby creating a 3D pattern of multiple vortices. Because the pattern reportedly depends on the oscillation frequency, it can be controlled.

To demonstrate its appropriateness for different applications, the researchers used the device to mix tiny droplets of highly viscous liquids. "The more viscous liquids are, the more difficult it is to mix them," the researchers explained. "However, our method succeeds in doing this because it allows us to not only create a single vortex, but to also efficiently mix the liquids using a complex three-dimensional pattern composed of multiple strong vortices."

Further, the team demonstrated that they could pump fluids through a mini-channel system by developing a specific pattern of vortices and placing the oscillating glass needle close to the channel wall.

Additionally, the robot-assisted acoustic device was used to capture fine particles in the fluid. It was determined that this worked because a particle's size dictates its reaction to the sound waves. As such, large particles tend to move toward and accumulate near the oscillating glass needle.

The team suggests that the device can capture biological cells in the fluid in addition to capturing inanimate particles.

In addition to applications for the device in the lab, the researchers believe it could also be used to sort tiny objects, used in additive manufacturing and 3D printing, or used in biotechnology as a means of introducing DNA into individual cells.

The research, A robot-assisted acoustofluidic end effector, appears in the journal Nature Communications.

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