Until now, tiny robotic systems had to get by without an arm. Now, researchers at ETH Zurich have developed an ultrasonically-actuated glass needle that can be attached to a robotic arm. This allows you to pump and mix minute amounts of liquid and trap particles.
We are all familiar with robots with movable arms. They can stand in the halls of the factory, do mechanical work and program. A single robot can perform various tasks.
To date, small systems that transport tiny amounts of liquids through tiny capillaries have had little relevance for such robots. Developed by researchers to aid in laboratory analysis, such systems are known as microfluidics or lab-on-a-chip and commonly use external pumps to move liquids into the chip. . Until now, such systems have been difficult to automate and have required custom-designed and manufactured chips for each specific application.
Ultrasonic needle vibration
Scientists, led by ETH professor Daniel Ahmed, are now combining conventional robotics and microfluidics. They have developed a device that uses ultrasound and can be attached to a robotic arm. It is suitable for performing a wide range of tasks in microrobotic and microfluidic applications and can also be used to automate such applications. The scientists report on this development in Nature Communications.
(Visualization: ETH Zurich)
The device consists of a thin, pointed glass needle and a piezoelectric transducer that vibrates the needle. Similar transducers are used in loudspeakers, ultrasound imaging, and professional dental cleaning equipment. ETH researchers can change the vibration frequency of the glass needle. By immersing the needle in liquid, it creates a three-dimensional pattern of multiple vortices. This pattern depends on the oscillation frequency and can be controlled accordingly.
Different swirl patterns in the liquid seen from above. Visualized by particles. The dot in the middle of each photo is the glass needle. (Photo: ETH Zurich)
Researchers have been able to use this to demonstrate several applications. First, they were able to mix small droplets of very viscous liquids. “The more viscous the liquid, the more difficult it is to mix,” explains Professor Ahmed. “However, our method does not just create a single vortex, but uses a complex three-dimensional pattern of multiple intense vortices to mix liquids efficiently, which is why it is possible to do this.” has been successful.”
Second, scientists were able to pump fluid through a minichannel system by creating specific patterns of vortices and placing vibrating glass needles near the channel walls.
Third, they used a robot-assisted acoustic device to successfully capture particulates present in fluids. This is because the particle size determines how it responds to sound waves. Larger particles move towards the vibrating glass needle and accumulate there. Researchers have demonstrated that this method can capture fish embryos as well as inanimate particles. They think it should also be able to trap living cells in fluids. “Until now, manipulating microscopic particles in three dimensions has always been difficult. Our microrobot his arm makes it easy,” says Ahmed.
“Mixing and pumping liquids and trapping particles – all in one device.”
Daniel Ahmed
“Historically, advances in large-scale conventional robotics and microfluidic applications have been separate,” says Ahmed. “Our work helps bring the two approaches together.” As a result, future microfluidic systems can be designed in a similar way to today’s robotic systems. A single properly programmed device can handle a wide variety of tasks. “Mixing and pumping liquids and trapping particles – one device can do it all,” says Ahmed. This means that future microfluidic chips will no longer need to be custom-developed for each specific application. The researchers next hope to combine multiple glass needles to create even more complex vortex patterns in liquids.
In addition to laboratory analysis, Ahmed can envision other applications for the microrobotic arm, such as sorting small objects. Arms also have potential uses in biotechnology as a way to introduce DNA into individual cells. Ultimately, additive he should be able to use for manufacturing and his 3D printing.
Original: Precision arm for small robots
Than: ETH Zurich
