a microrobot developed to administer drugs, it simulates the movements of starfish larvae. The project, carried out by the researchers of theETH of Zurich, is characterized by sound waves and has tiny hairs that direct the fluid around it, just like its natural pattern. In the future, such micronotors could deliver drugs to diseased cells with the utmost precision.
The results of the studio have been published in the prestigious scientific journal Nature Communications.
Microrobot: their function will be to deliver drugs to our body with absolute precision
There is great interest among scientists in the microscopic machines destined to revolutionize medicine. These microrobots, often only a fraction of the diameter of a hair, are made to swim through the body to deliver drugs to specific areas and perform the smallest surgical procedures.
The designs of these robots are often inspired by natural microorganisms such as bacteria or algae. Now, For the first time, a research team from ETH Zurich has developed a microrobot design inspired by starfish larvae, which use ciliary bands on their surface to swim and feed. The ultrasound-activated synthetic system mimics the natural arrangements of starfish’s ciliary bands and uses non-linear acoustics to replicate the larva’s movement and manipulation techniques.
At first sight, microrobots have only few similarities to starfish larvae. In its larval stage, a starfish has a lobed body measuring only a few millimeters in diameter. Meanwhile, the microrobot is a rectangle and ten times smaller, only a quarter of a millimeter in diameter. But the two share an important characteristic: a series of fine, mobile hairs on the surface, called eyelashes.
A starfish larva is covered in hundreds of thousands of these hairs. Arranged in rows, they flap back and forth in a coordinated fashion, creating eddies in the surrounding water. The relative orientation of two rows determines the final result: tilting two bands of flying lashes towards each other creates a vortex with a pushing effect, pushing the larva. On the other hand, the inclination of two bands from each other creates a vortex that attracts the liquid, trapping the particles that the larva feeds on.
These cilia were the key design element for the new microrobot developed by ETH researchers led by Daniel Ahmed, pProfessor of Acoustic Robotics for Life Sciences and Healthcare. “At the beginning“Said Ahmed,”We simply wanted to test if we could create starfish-like vortices with rows of lashes tilting towards each other or away from each other.“.
A tal fine, the researchers used photolithography to build a microrobot with suitably inclined ciliary bands. They then applied ultrasonic waves from an external source to swing the lashes. Synthetic versions beat back and forth more than ten thousand times per second, about a thousand times faster than that of a starfish larva. And as with the larva, these flying lashes can be used to generate a vortex with a suction effect in the front and a vortex with a push effect in the back, the combined effect “pushes” the robot forward.
In their laboratory, Researchers have shown that microrobots can swim in a straight line through liquids such as water. Adding tiny plastic beads to the water made it possible to visualize the swirls created by the microrobot. The result is surprising: both starfish larvae and microrobots generate virtually identical flow patterns.
Next, the researchers arranged the ciliary bands so that a suction vortex was placed next to a thrust vortex, mimicking the feeding technique used by starfish larvae. This arrangement allowed the robots to collect particles and send them in a predetermined direction.
Ahmed is convinced that this new type of microrobot will be ready for use in medicine in the near future. This is because a system that is based only on ultrasound offers decisive advantages: ultrasound waves are already widely used in imaging, penetrate deep inside the body and pose no health risk.
The fact that this therapy only requires an ultrasound device makes it cheap, he adds, and therefore suitable for use in both developed and developing countries.
The scientist believes that a first field of application could be the treatment of gastric cancers. Absorption of conventional drugs by diffusion is inefficient, but having microrobots transport a drug specifically to the site of a stomach tumor and then deliver it there could make drug absorption more efficient in the stomach. cancer cells and reduce side effects.
Before this vision can be realized, there remains a major challenge to overcome: imaging. Driving the tiny cars to the right place requires a sharp image to be generated in real time. Researchers plan to make microrobots more visible by incorporating contrast agents such as those already used in medical ultrasound imaging.
In addition to medical applications, Ahmed predicts this starfish-inspired design will have important implications for handling small volumes of liquids in research and industry.. The flapping bands of lashes could perform tasks such as mixing, pumping, and trapping particles.
